KAYAK EXERCISER MACHINE

MIM U701-702

Technical Design Report

KAYAK EXERCISER MACHINE

Final Report

Design Advisor: Prof. Grant Warner

Design Team Miriam Barsalou, Matthew Cupka, Nick Fedas Craig McGreevy, Amy Wojtowicz

April 18, 2006

Department of Mechanical, Industrial and Manufacturing Engineering College of Engineering, Northeastern University Boston, MA 02115

Acknowledgments

We the team members,

Miriam Barsalou, Matthew Cupka, Craig McGreevy, Nick Fedas and Amy Wojtowicz

Would like to acknowledge and thank the following individuals for their help, devotion and time that they have given us when they clearly had important things to take care of themselves.

Our Advisor: Professor Grant Warner Capstone Supervisor: Professor Greg Kowalski Capstone Machine Technician: Jon Doughty Capstone Lab Technicians: Richard Weston, LeBaron Briggs Faculty Advisors: Professor Jeff Doughy, Professor Jeff Ruberti, Professor Thomas Cullinane, Prof. Mohammed Taslim, Prof. Sinan Muftu Capstone TA’s: Zeynep D. Ok, Ipek Stillman Northeastern Faculty: Linda Cincotti, Noah Japhet

We would like to thank all the other Capstone groups for their help and support as well. The capstone lab clearly would not have been the same without our friends and classmates right there with us.

We would like to thank Asst Director of Campus Recreation, Kristen Miller, and the Department of Athletics for providing our group with a Concept II rowing machine to help support the prototype we had developed and to allow us to test our design first hand.

Finally, we would like to thank the individuals that assisted in our research and gathering potential customer feedback on kayaks, kayak ergometers and changes they would like to see made to currently available kayaks.

Copyright

“We the team members,

Miriam Barsalou Matthew Cupka Craig McGreevy Nick Fedas Amy Wojtowicz

faculty advisor – Professor Grant Warner

Hereby assign our copyright of this report and of the corresponding Executive Summary to the Mechanical, Industrial and Manufacturing Engineering (MIME) Department of Northeastern University.” We also hereby agree that the video of our Oral Presentations is the full property of the MIME Department.

Publication of this report does not constitute approval by Northeastern University, the MIME Department or its faculty members of the findings or conclusions contained herein. It is published for the exchange and stimulation of ideas.

KAYAK EXERCISER PROJECT

Design Team Miriam Barsalou, Matthew Cupka Nick Fedas, Craig McGreevy, Amy Wojtowicz

Design Advisor Prof. Grant Warner

Abstract

Currently available kayak ergometers do not incorporate the complete kayak motion. Research and consumer feedback show these training devices have shortcomings when it comes to balance training, and torso involvement. To address this issue an improved platform was developed for use with the Vermont Waterways Concept II adapter (Figure 1). The platform will include a cockpit, with features similar to those of a real kayak, which will allow the yaw and roll motion one experiences when using a kayak on water. By increasing the involvement of the lower body and incorporating the need for balance into the ergo-meter, the platform will give the user a better workout and training routine. The lower body adapter includes adjustable features such as thigh braces and a braking system to allow the user to vary the level of resistance.

Acknowledgments...... ii Copyright ...... iii Abstract...... iv List of Figures...... viii List of Tables ...... ix 1 Introduction...... 1 2 Project Description...... 1 3 Research...... 2 3.1 Existing Machines...... 2 3.1.1 KayakPro Speedstroke and Dansprint ...... 3 3.1.2 Vermont Waterways Concept II Adaptor ...... 4 3.2 Biomechanics...... 4 3.2.1 Muscle Groups...... 5 3.2.1.1 Leg use differences in different kayaks ...... 6 3.3 Communication with kayakers ...... 7 3.4 Kayak stroke...... 8 3.4.1 Righting moment ...... 8 4 Project Concept...... 11 5 Design Requirements...... 13 5.1 Basic Requirements ...... 13 5.2 Pivot Mechanism Requirements ...... 13 5.3 Cockpit Requirements...... 13 5.4 Kayak Adaptor for Concept II Requirements ...... 14 5.5 Special Considerations...... 14 5.6 Number of Cycles...... 14 6 Previous Designs...... 15 6.1 One piece cockpit...... 15 6.2 Separate pivot mechanism and leg braces ...... 15 6.2.1 Leg braces...... 16 6.2.2 Pivot mechanisms ...... 16 6.2.2.1 Ball and socket...... 17

v 6.2.2.2 Hull shaped pivot support with separate resistance and range of motion...... 17 6.2.2.3 Rounded rectangle pivot support with extension spring resistance...... 18 7 Design ...... 18 7.1 Pivot mechanism with cockpit...... 19 7.1.1 Pivot mechanism...... 20 7.1.1.1 Attachment...... 21 7.1.1.2 Roll Mechanism...... 22 7.1.1.3 Yaw Mechanism...... 23 7.1.1.4 Torsion Spring System...... 24 7.1.1.5 Compression Springs...... 25 7.1.2 Cockpit...... 26 7.2 Concept II Kayak Stroke Adaptor...... 27 8 Cost Analysis...... 29 9 Future improvements ...... 32 9.1 Resistance mechanism ...... 32 9.2 Roll and yaw brakes...... 33 9.3 User friendly cockpit...... 33 9.4 Improved pivot mechanism attachment...... 33 9.5 Restrict yaw range of motion...... 33 9.6 Kayaker improvement feedback ...... 34 10 Conclusion ...... 34 Works Cited and Consulted ...... 35 Appendix A - Kayaker survey ...... A-1 Appendix B - Kayaker Feedback...... B-1 Kayaking as an exercise...... B-1 Uses for a Kayaking machine ...... B-2 Features of a machine ...... B-3 Opinions on currently available machines...... B-5 Appendix C - Biomechanical Analysis...... C-1 Appendix D - Types of Kayak...... D-1 Appendix E - Material Calculations ...... E-1

vi E-1 – Number of Strokes in Device’s Lifetime ...... E-2 E-2 – Cockpit mass and center of gravity calculations...... E-3 E-3 - Distribution of the Loads on the pivot supports ...... E-5 E-4 – Pivot mechanism shaft diameter ...... E-6 E-5 – Roll bearing calculations...... E-8 E-6 – Determination of yaw shaft diameter...... E-9 E-7 - Pivot mechanism screw calculations ...... E-10 E-8 – Torsion Spring calculations...... E-12 E-9 - Compression spring calculations ...... E-13 Appendix F – Pivot Mechanism and cockpit drawings ...... F-1 Appendix G – Upper Body Adaptor ...... G-1 Appendix H – Cost Analysis...... H-1

vii List of Figures

Figure 1 - Speedstroke Ergometer by KayakPro [4] 3 Figure 2 - Dansprint Ergometer [5] 3 Figure 3 - Vermont Waterways Concept II Kayak Adaptor [1] 4 Figure 4 - Major muscle groups used in kayaking [13] 5 Figure 5 - Components of a whitewater kayak cockpit [8] 7 Figure 6 - Kayaker demonstrating roll and yaw motions 8 Figure 7 - Degrees of heal against the horizontal distance with different shapes [10] 9 Figure 8 - CG and CB change and result in a change in horizontal distance [10] 10 Figure 9 - Righting moments of the Pisces Ocean Kayak 11 Figure 10 - Vermont Waterways Concept II Kayak Adaptor [1] 12 Figure 11 - A one piece cockpit brainstorm idea 15 Figure 12 - Solidworks model demonstrating separate pivot mechanism and leg braces 16 Figure 13 - The brainstorming picture of the external frame leg braces 16 Figure 14 - Ball and socket mechanism 17 Figure 15 - Hull shaped pivot support 17 Figure 16 - Full design model on Concept II rower 18 Figure 17 - Picture of full design on Concept II rower 19 Figure 18 - Pivot mechanisms and cockpit assemblies on the Concept II I-beam 19 Figure 19 - Pivot mechanism assembly with named parts 20 Figure 20 - Picture of assembled pivot mechanism 22 Figure 21 - Cosmos analysis of pivot support 23 Figure 22 - Inner ring assembly of tapered roller bearing [12] 23 Figure 23 - Torsion Spring inside pivot mechanism assembly 24 Figure 24 - Linear moment of roll springs 25 Figure 25 - Cockpit assembly 26 Figure 26 - Cockpit of prototype with folded down thigh hook support 27 Figure 27 - Picture of upper body adaptor on the concept II rowing machine 28 Figure 28 - Top view of upper body adaptor 29 Figure 29 - Flatwater Racing Kayak Evolution Extreme [9] D-1

viii Figure 30 – Ocean Kayak Specter 14.0 w/ Rudder [8] D-2 Figure 31 - Whitewater Kayak Rx 6.9 [8] D-3

List of Tables

Table 1 - Forces and moments in joints...... 5 Table 2 - Prices for currently available Ergometers ...... 30 Table 3 - Parts list of both the pivot mechanism and the cockpit...... 31 Table 4 - Parts purchased through school funding for prototype...... 32

ix

1 Introduction

Kayaking is an outdoor sport practiced on water. During winter when bodies of water are frozen or dangerously cold and daylight limited, or during adverse weather conditions, the kayaker may not be able to practice his or her sport in a boat. As these conditions can last for several months, a practical alternative must be available for land training. While kayaking in its several forms is a popular sport, the watersport exerciser market is dominated by rowing machines. Currently available kayaking exercisers focus primarily on the relatively stable, open cockpit flat-water kayak, and are generally geared towards the competitive kayaker. These exercisers include the upper body motions performed by the kayaker, but not the legs or the abdominal exercises used for balancing the boat and guiding the boat through water.

Initially charged with creating an adaptor for a rowing machine, this project has now been focused on creating a mechanism that would train the torso muscles used during kayak balancing, propelling and steering of the boat. The group will still create a general kayak stroke adaptor for a rowing machine. Ideally, the balance mechanism would be used with a kayak adaptor currently available on the market. Therefore the kayak adaptor created in this project will approximate the kayak stroke and will be used to verify the function of the balance mechanism.

2 Project Description

The project was assigned to the group during Northeastern University’s Capstone Design Class in May 2005 with a goal of retrofitting a rowing machine into a kayaking machine taking into account the proper biomechanics of the full kayaking stroke.

After initial research was completed, it was understood that a Concept II rowing machine kayak adapting device was already in existence. The design goals were changed to focus the project on a kayak cockpit on a balance mechanism and the modification of a Concept II rowing machine to approximate the kayaking upper body motion. The design will be an exerciser as well as a

1 simulator. An exerciser would permit the user to train the muscles used in kayaking, while a simulator would attempt to mimic the motions encountered by a kayaker while practicing in the boat. Seeing as our goal is an off-season training tool, a machine which simulates the motion of the boat will allow the user to train his or her sport specific muscles. For example, by incorporating a yaw motion, the device’s cockpit would simulate the reactions of the boat when the boat’s paddle moves through the water allowing the user to control the cockpit using his or her torso muscles as they would in the boat.

3 Research

Research was conducted to further understand the project. Topics covered were: existing kayaking machines, their advantages and disadvantages; the biomechanics of kayaking, including the muscle groups and variations between different kinds of kayaks; recommendations by kayakers of various backgrounds; and the motion of the kayak stroke.

3.1 Existing Machines

Through research and communication with kayakers it was found that several exercise machines for kayakers were already in existence. All the machines are available in the United States only through special orders. Machines researched in detail included the KayakPro Speedstroke, the Dansprint, and the Vermont Waterways Concept II Kayak Adaptor. The Vermont Waterways product is an adaptor that retrofits the Concept II rowing ergometer into a kayak exercise machine. All of these machines are generally designed to provide a stable cardio platform for a flat-water racing kayak, such as those seen in the Olympics.

2 3.1.1 KayakPro Speedstroke and Dansprint

Figure 1 - Speedstroke Ergometer by KayakPro [4]

Figure 2 - Dansprint Ergometer [5] Both the Speedstroke by KayakPro (shown in Figure 1) based in New Rochelle, New York, [4] and the Dansprint Ergometer (shown in Figure 2) based in Denmark [5], are stand-alone kayaking ergometers. These machines are common in National Team training centers, but their cost and low availability make them impractical for regular gyms. While the Concept II rowing machine, common in gyms, is priced at $850 [6], the Speedstoke costs $2000 [4] and the

3 Dansprint was priced 3.197,00 EU [5] which as of April 13, 2006 is equivalent to approximately $3868. Similar in design, both machines are stable cardiovascular platforms that do not provide enhanced core or leg workouts.

3.1.2 Vermont Waterways Concept II Adaptor

The Vermont Waterways Adaptor is based on a Concept II rowing machine which, as previously mentioned, is common in gyms. The adaptor attached to a rowing machine is shown in Figure 3. The Vermont Waterways adaptor provides a similar motion to the above mentioned machines, but uses a rowing machine as its base. It appears from kayaker feedback that the stroke of the adaptor does Figure 3 - Vermont Waterways Concept II Kayak not provide as smooth a motion as the kayak Adaptor [1] specific machines, but at a cost of $775 [1] it is the most inexpensive alternative of the three for the kayaker who already has access to a Concept II rowing machine. Like all current kayak machines, it is a stable upper body cardiovascular exerciser.

3.2 Biomechanics

To better understand the kayaker’s motions and to complete the requirements for a biomechanics minor required by several members of the group, it was necessary to do a full body force analysis during a single moment of the kayak stroke.

To complete the body force analysis, we developed a free body diagram to calculate the initial forces down on the pivot mechanism. We then used those free body diagrams to find the resulting forces. The resulting forces were used to determine the forces and moments at many of the joints. The full calculations, including assumptions, for each part analyzed can be found in

4 Appendix C. The forces in the x and y direction and the moment experienced at each major joint can be found in Table 1.

Table 1 - Forces and moments in joints Force-X Force-Y Moment Joint (N) (N) (N*m) Ankle -44.45 -57.63 -2.005 Knee 44.45 119.762 16.55 Hip -164.45 -1245.56 110.41 Wrist -96.728 28.0164 4.0723 Elbow 86.909 -4.4508 26.48 Shoulder -96.454 -45.7324 51.42

3.2.1 Muscle Groups

Several muscle groups are susceptible to injury during the kayak stroke. A desire to maintain these muscles during the “off season” and to prepare for reentry into the sport after injury led to the focus in our research. The muscles vulnerable in kayaking include the shoulder muscles, especially those around the rotator cuff, the muscles of the torso and the muscles of the legs, shown in Figure 4. It should be noted, however that the use of the legs varies between different kinds of kayak. Currently available kayaking machines all train the shoulder muscles, providing adequate support to the rotator cuff. The shoulder muscles are used by all

Figure 4 - Major muscle groups used in disciplines of kayakers. kayaking [13]

5 The abdominal muscle training experienced in kayaking is mostly experienced because of the twisting about the normal axis motion experienced while taking kayak strokes. This is accentuated in the boat by the reaction to paddle in the water.

Current kayak machines all practice the leg motions exerted by a flat-water kayaker. However, the flat-water leg motion is not fully accurate on the Concept II adaptor, since there is no back support for the kayaker to push against.

3.2.1.1 Leg use differences in different kayaks

There are dozens of kinds of different kayaks available on the market. The kayak selected varies by the skill level of the kayaker, the kind of water the kayaker wishes to navigate, whether the kayaker wishes to compete, the kayaker’s size and strength, and the length of the kayakers trip to name a few. While there are dozens of categories, the group has chosen to lump most kayaks into three groups, flat water competitive, ocean, and whitewater.

Flatwater competitive kayaks are long and narrow. The kayaker sits with his or her legs in free motion. Ocean kayaks are long but wider than the flatwater kayak. These kayaks are often designed for long trips. The ocean kayak has a backrest like the flatwater kayak, but the ocean kayaker also has thigh hooks in the boat’s cockpit to help support their motion. The kayaker’s feet are only in contact with steering pedals. Whitewater kayaks tend to be short, wide and maneuverable. Maintaining position within the cockpit of this kayak while paddling is essential, therefore the kayaker is fully braced with thigh hooks, side braces and a backrest while in the kayak. These components are pointed out in Figure 5. Examples of all three kinds of kayak are found in Appendix D.

6

Figure 5 - Components of a whitewater kayak cockpit [8]

The leg use for different kayaks has to do with kayaker’s position in the boat. The flat-water racing boat has an open cockpit which allows the leg motions to move freely, keeping most of the pressure against the backrest and the foot plate. The ocean touring and whitewater kayaks enclose the kayaker’s legs. The kayaker must put pressure against the thigh hooks of the enclosed area from a “frog legged position”, with the knees bent out, to stabilize his motions while in the kayak.

3.3 Communication with kayakers

Kayakers of different backgrounds and abilities were asked to fill out a short questionnaire, found in Appendix A. Some had used a kayak exerciser prior to being surveyed while others had not. This led to a wide variety of responses when asked what they would like to see in a kayak exerciser. The complete report of feedback from these kayakers can be found in Appendix B. A response common amongst all levels and experiences was a desire for balancing aspects. While most envisioned the balancing device in different ways, a commonality was increased work to their core muscles. Kayaks require a great deal of balance as they are unstable platforms on the water. Training these core muscles would allow the kayaker to better prepare for the upcoming kayak season by toning their core. In addition, the propulsion of the kayak through the water produces a yaw motion which the kayaker must counteract using their core muscles. Kayakers

7 from ocean and whitewater disciplines also mentioned that thigh braces or hooks of some sort would better prepare them for the forces exerted by their legs as mentioned in section 3.2.1.1.

3.4 Kayak stroke

In normal kayak operation, the kayaker experiences roll and yaw of their boat as shown in Figure 6. Roll is the rotation about the longitudinal axis or the side to side motion. While yaw is the rotation about the normal axis, or a twisting side to side motion.

In order to understand how many cycles the device must be designed to, the group must understand how many strokes are taken during a normal kayak operation. Several instructional websites stated that an ocean kayaker will take Figure 6 - Kayaker demonstrating roll and yaw motions 50 to 60 strokes per minute [7]. This is the number of strokes per minute used to calculate how many strokes would be taken in the design life of our device.

3.4.1 Righting moment

The righting moment represents the range of roll motion that the pivot device allows in order to exercise kayak specific muscles. The righting moment in a kayak refers the amount buoyancy force put against the kayak by the water keep the kayak upright. When kayaker are rocks their boat back and forth in the water, the righting moment is the force that pushes the boat back to its normal vertical position. The righting moment calculation depends on several things including the weight and the shape of the kayak. The shape of the kayak’s underbelly can dramatically change the resulting righting moment depending on how the kayak sits in the water. The Figure 7 shows several different shapes and how the horizontal distance, GZ, is affected by these

8 different shapes. The horizontal distance is proportion to the righting moment or the amount of force applied by water buoyancy.

Figure 7 - Degrees of heal against the horizontal distance with different shapes [10]

To better understand the righting moment, it is important to understand the degree of heel. Gz is the maximum distance between the center of gravity, CG, and the center of buoyancy, CB. The maximum distance will show the degree of heal, angle of tilt, where the maximum buoyancy force will be on the kayak. Figure 8 shows how, as the degrees of heal increase, the CG and CB are affected and that the maximum righting moment is the maximum distance between CG and CB. As the user leans to the left, both CG and the CB adjust to the left and at 20.4º GZ reaches its maximum. As the distance increases from CB and CG the righting moment will increase, reaches it’s peak at approximately 0.047ft and then declines. During the declining stage there is less righting moment and as soon as CG passes CB at approximately 37.5º there is no force remaining to right the user, and the boat will most likely tip.

9

Figure 8 - CG and CB change and result in a change in horizontal distance [10]

The righting moment is achieved to the pivot mechanism by adding a resistant force that will push back as the user rolls left or right. Since there are many different righting moments based on the shape of the kayak, a specific kayak was chosen based on averages and common shapes of kayaks. The base reference kayak used is the Pisces ocean kayak. The righting moment calculations for this boat have been researched so they can be applied to the pivot mechanism design.

The righting moments on an actual kayak are exponential and are very difficult to imitate. A linear setup for the pivot mechanism will be designed to allow the same amount of maximum force as the pisces kayak. Figure 9 shows the righting moment on the Pisces. In addition to the righting moment, it was important to make sure the user would stay on the pivot mechanism.. After comparing the maximum degrees the pivot mechanism can safely tilt and the maximum righting moment of the kayak, 20º was the decided range of motion. It is not too large for the user and it is relatively close to the maximum righting moment of the Pisces kayak.

10

Figure 9 - Righting moments of the Pisces Ocean Kayak

4 Project Concept

After learning that Vermont Waterways already sold a kayak adapter, the focus was shifted to improving a currently available kayaking machine. It was decided that the most dramatic change that could be made to a currently available machine was to incorporate a balance aspect and thigh hooks, useful to ocean and whitewater kayakers. The goal of the balance seat would be to simulate the balancing experienced in the boat, which would train and strengthen the abdominal muscles and encourage the user to maintain proper posture in order to maintain cockpit position.

While the Vermont waterways adaptor, shown in Figure 10 is designed for flatwater racing it is not perfect to this purpose. The seat could use more back support to increase the pressure exerted by the legs during flat water motion.

11

Figure 10 - Vermont Waterways Concept II Kayak Adaptor [1]

The group was unable to acquire a Vermont Waterways Concept II Kayak Adapter, shown in Figure 10, for this project. The Vermont Waterways kayak machine was selected because the Concept II rowing machine is a popular rowing exerciser in gyms, and was readily available to the group for initial measurements and design. In order to successfully prove our balance mechanism, upper body reactions are necessary. Therefore another objective of this project will be to modify a Concept II rowing machine to provide kinematically correct upper body motion experienced in the kayak motion. This will be a simplified version of the Vermont Waterways Adaptor. While this may seem similar to our original goal of modifying the Concept II rowing machine, the adaptation of the Concept II is not the focus of this design and minimal calculations will be made. However, this is an important part of the project due to testing and verification needs.

12 5 Design Requirements

The pivot mechanism and cockpit are one assembly but each has different design requirements. The group established basic requirements as well as separate design requirements for the pivot mechanism, the cockpit, and the Concept II kayak stoke adaptor.

5.1 Basic Requirements

All aspects of the design should pass certain design requirements. o Little or no impact to the Concept II rowing machine o Inexpensive o Adjustable and removable. o All parts are easily machinable o All parts must work to a factor of safety of at least 2 o Adjustable for users from 5’ to 6’6” o Weight range of users is: 100lbs to 300lbs

5.2 Pivot Mechanism Requirements

Several decisions must be made to determine the factors of success of the pivot mechanism. These include along how many axes the mechanism will rotate, how to constrain the mechanism’s range of motion, and which materials will be able to withstand the loads and stresses encountered. The established base design list is as follows: o The pivot mechanism will allow the cockpit to roll and yaw o The pivot mechanism will be constrained to a certain range of motion. o There should be a lock on the seat to allow the user to exercise without having to balance o The pivot mechanism should not allow pitch. o When off balance, the balance mechanism should experience righting moments like in the boat to help the user return to balance.

5.3 Cockpit Requirements

The cockpit will be attached to the pivot mechanism. It is where the user sits and should simulate the cockpit of a kayak. The base design requirements are: o The cockpit will mimic dimensions of real kayaks

13 o The cockpit will have thigh hooks like an ocean or whitewater kayak o The leg brace assembly can not interfere with the stroke or cords to the flywheel. o The area in contact with the legs will be padded. o The cockpit will be easy for user to get in and out of.

5.4 Kayak Adaptor for Concept II Requirements

While the adaptor is not the focus of this project, it is required in order to achieve proper upper body reactions in relation to the lower body reactions being generated by our devices. Therefore there are basic requirements which must be met by this design. o The adaptor will use the Concept II’s flywheel to provide upper body resistance o The adaptor’s kayak paddle should not hit the ground. o The adaptor’s cords should allow for enough clearance for the cockpit of the project’s pivot mechanism.

5.5 Special Considerations

In order to minimize damage done to the Concept II rowing machine base model, several extra design considerations are taken note of: o No drilling can be done to the base model. o The Surface finish of the I-Beam must be maintained o Considerations should be taken to protect the edges of the “I” of the I-beam. o Cyclical loading should not damage the I-Beam

5.6 Number of Cycles

In order to determine material properties, the group must decide how many cycles the device will undergo in a typical lifetime. As mentioned in section 3.4 a typical ocean kayaker will take 50 to 60 strokes a minute during exercise. The group decided on a 5 hour per day use 365 days a year for 3 years. This resulted in a value of just less than 20,000,000 cycles. The full calculations can be found in Appendix E-1. The value will be used to calculate parts subject to cyclical loading such as bearings and springs.

14 6 Previous Designs

Throughout the design process, the group’s goals and requirements changed rather frequently. In order to satisfy the design requirements at the time, several designs were considered. These designs fell into two general categories, the one piece cockpit and the two part pivot mechanism and leg brace concept. The two part pivot mechanism concept generally maintained the same leg brace configuration throughout the design evolution.

6.1 One piece cockpit

The one piece cockpit was visited early on in a brainstorming session. The design, shown in Figure 11 called for a long device along the Concept II’s I-beam. This device would be allowed to roll through springs at each end of the I-beam. The device would Figure 11 - A one piece cockpit brainstorm idea be allowed to roll along the shaft in the center of the device. Advantages: The primary advantage discussed for a 1 piece system was that a cockpit would mimic the reactions of a real boat better. The seat assembly would have incorporated the thigh hooks and the backrest. Disadvantages: The disadvantages seen for this concept included that it was too complicated to machine, that it would be too heavy and expensive and that the springs used for roll would provide too much unintentional pitch. In future design considerations, this design would not have easily accommodated a yaw motion.

6.2 Separate pivot mechanism and leg braces

During a brainstorming session, the group decided that it wanted to have a design that would have separate pivot mechanism and leg braces, like that shown in Figure 12. This was decided because at the time it was felt that the stationary legs would be safer for the user, as they would not twist the kayak adaptors cords and provide a better isometric exercise for the user. This

15 concept idea was eventually changed, because in order to achieve kayak specific muscles, kayak specific motions must be performed.

6.2.1 Leg braces

During brainstorming sessions, two designs for the separate knee braces where presented. The first wrapped around the kayaker’s legs, like in a kayak, and the second came up between the user’s legs.

The second option was chosen for further Figure 12 - Solidworks model demonstrating separate investigation because it would be easier for pivot mechanism and leg braces the user to sit in and adjust. In addition there was concern that the external frame design was too bulky and would interfere with the cords of the adaptor. The external frame leg brace brainstorm picture can be seen in Error! Reference source not found. while the internal ideal is part of Figure 12.

6.2.2 Pivot mechanisms

Several pivot mechanisms were investigated to work with the separate leg braces. The advantage to the separate pivot mechanism eventually lay in the easy modifications to incorporate yaw motion. Three main pivot mechanism ideas visited were the ball and socket joint, the pivot support on a Figure 13 - The brainstorming picture of the external rotating shaft with a hull shape, and the frame leg braces pivot support with extension spring resistance.

16 6.2.2.1 Ball and socket

The ball and socket joint concept had a ball shaped pivot support within a case which acted as a socket. A basic model of this concept is shown in Figure 14. Advantage: Allowed the kayaker to pitch, yaw and roll. Disadvantages: Inability to restrict the range of motion of the ball within the socket to provide different degrees of freedom in different directions. Providing resistance to the mechanism was Figure 14 - Ball and socket also difficult, a considered solution would have required taking mechanism into consideration wear rates as well as the effect of wear particles within the ball joint. In addition the group had concerns about how to lubricate the ball joint so it would be able to perform the proper motions.

6.2.2.2 Hull shaped pivot support with separate resistance and range of motion

A concept which was developed and evolved was an idea of a pivot mechanism that rotated freely on a shaft supported by bearings on either end. An early concept for the pivot support idea was the hull shaped pivot support shown in Figure 15. The initial concept was to achieve the righting moment of the boat through the inertial and geometry of the pivot support. The idea was abandoned when it was realized that the part’s size restrictions made it too small to achieve any kind of inertia advantage. In addition the part was not practically designed for machinability and would have been Figure 15 - Hull shaped difficult to make. pivot support

This design also had two separate components that would have worked with the roll shaft to restrict range of motion and change resistance. Several ideas were investigated for an adjustable range of motion device, including one which would provide the user with a lock, beginner and advanced range, but none were found to be appropriate. In addition a resistance mechanism would have been attached to the other end of the shaft. This device would have been adjustable

17 so that users of different weights could adjust the resistance to similar values. Both mechanisms were abandoned when it was decided that the range of motion did not need to be adjustable.

6.2.2.3 Rounded rectangle pivot support with extension spring resistance

This concept is very similar to the chosen concept. The righting moment resistance was achieved with extension springs instead of torsional spring. The pivot supports had a flange on each side of their body. These flanges were connected to springs to provide resistance. Disadvantages: While springs were easily found, how to manufacture the flanges and attach the springs became an issue. In addition, the size of the required springs made the case much larger than initially designed.

7 Design

The final design for the prototype in this project can be divided into two main parts, the pivot mechanism, which includes the cockpit, and the upper body adaptor. The model of the designs attached to a model of a Concept II rowing machine is shown in Figure 16.

Figure 16 - Full design model on Concept II rower A picture of the prototype is shown in Figure 17. The picture provides a better look at the upper body adaptor’s ropes and paddle attachment.

18

Figure 17 - Picture of full design on Concept II rower

7.1 Pivot mechanism with cockpit

Figure 18 - Pivot mechanisms and cockpit assemblies on the Concept II I-beam

19 The pivot mechanism and cockpit are one assembly when attached to the concept II I-beam, as shown in Figure 18. The cockpit is attached to the yaw flange on the pivot mechanism otherwise they are two separate components and will be treated as such in this paper.

7.1.1 Pivot mechanism

Figure 19 - Pivot mechanism assembly with named parts The full pivot mechanism, shown in Figure 19, should provide a roll and a yaw motion. The device can be divided into three main components for description and calculation explanation. These parts are the attachment, the roll mechanism and the yaw mechanism. The attachment includes the clamping plates, and the casing base. The roll mechanism includes the pivot support,

20 the casing, the roll shaft, the roll bearings, and the spring pins. The yaw mechanism includes the yaw block, the yaw bearing, the yaw shaft and the yaw flange. The torsion springs are part of the roll mechanism, but for the purpose of description and analysis they will be discussed separately. The drawings for all machined parts of the assembly are found in Appendix F.

7.1.1.1 Attachment

The pivot mechanism must be attached to the Concept II I-beam. Because of the geometry of the Concept II’s I-beam’s foot, the mechanism must attach in a way that does not interfere with the metal flange that attaches to the bottom of the I-beam. In addition the I-beam has a slightly asymmetrical geometry, the top part of the “I” is 3 1/8” wide, 1/8” wider than the bottom part. The solution found in this design is to attach two clamping plates 3 1/8” apart to the bottom of the casing base at an equal distance from the center of the casing base. Each clamping plate is attached to the casing base using three #4 screws. The calculations for screws are found in Appendix E-7. These clamping plates were made of 1/8” 6061 aluminum to allow deflection of the plates under load. The bottom of the clamping plates has two ¼” clearance holes, these holes are placed at distances far enough that they will not interfere with the Concept II’s foot. Two 4” long screws are inserted across the clearance holes and the clamping plates are tightened using nuts.

This method of attachment depends on a horizontal force. Future improvements to the attachment would allow the pivot mechanism to be attached using a vertical force.

21 7.1.1.2 Roll Mechanism

The roll mechanism, shown in Figure 20, allows for motion along the longitudinal axis. It is composed of the four sides of the casing, the roll shaft, two roll bearings, two pivot supports, two spring pins and a support spring pin. The front and back pieces of the casing each contain a roll bearing and a spring pin.

Figure 20 - Picture of assembled pivot mechanism Both components are press fit to the casing. The pivot supports are press fit to the roll shaft parallel to each other and secured by a set screw. The yaw block is attached to the top of the pivot support. The support spring pin is pressed through the pivot supports. Assembly follows by attaching the side walls of the back piece of the casing, the torsion springs are incorporated and aligned as one end of the stepped roll shaft assembly is inserted into the back roll bearing. The other torsion spring is placed and the front casing wall attached to the side casing walls. The entire assembly is attached to the casing base with screws coming up from the casing base.

Several factors had to be considered and calculated in order to find the materials for the pivot mechanism. First, the force distribution on the pivot supports (yolks) was calculated in Appendix E-3. Using this data the minimum roll shaft diameter was calculated in appendix E-4. Then the dynamic load on the bearings was calculated in Appendix E-5. The screws used in the assembly were verified in Appendix E-7. Through these calculations it was decided to use a flanged open roller bearing, to minimize the thickness of the casing walls. The chosen roll

22 bearings were for 5/8” shafts with an outer diameter of 1 ½” with a dynamic load of 769 lbs. Using 316 stainless steel, the shaft diameter only needed to be ½”. The group used a ¾” shaft found among the machine shop’s spare part inventory. The screws used throughout the assembly were #4-40 screws for consistent application. Machined parts were analyzed using CosmosWorks, Solidworks’ FEA analysis program. The minimum criterion for success was a factor of safety of 2. An example of cosmos stress distribution of the pivot support is shown in Figure 21. This analysis was especially important Figure 21 - Cosmos analysis of pivot support when analyzing tapped holes. We wanted to make sure the part could handle the same loads the screws could.

7.1.1.3 Yaw Mechanism

The yaw motion of the kayak adapter is provided by 4 essential parts; yaw block, the tapered bearing, the yaw shaft and the flange. The yaw block connects the yaw assembly to the roll assembly. This block, which houses the tapered bearing sits on top of both pivot supports and is connected to them with #4 screws. The bearing choice for the yaw motion was a tapered-roller bearing. This bearing was chosen because of its ability to handle both radial and thrust loads. The tapered bearing is a two piece design that includes an inner ring and roller assembly, shown in Figure 22, plus an outer ring. This design offers excellent strength, a high load capacity, and a long

life. The specific bearing chosen has a shaft diameter of 1/2” and an Figure 22 - Inner ring outer diameter of 1 3/8”. This specified bearing can handle a radial load assembly of tapered of 710 lbs, and a thrust load of 550 lbs. These loads will adequately roller bearing [12]

support the anticipated Fseat loads.

The bearing’s outer ring is press fit into the yaw block. The yaw shaft is stepped so the smaller diameter will slip fit to the inner diameter of the inner bearing ring. The yaw shaft is ½” in diameter where press fit into the bearing and steps to ¾” diameter for the rest of its length. The

23 minimum shaft diameter is calculated in Appendix E-6. The shaft is short to reduce bending stresses. The other end of the yaw shaft is threaded and is screwed into the threaded yaw flange. The yaw flange attaches to the bottom of the cockpit. This allows the cockpit to react to the roll and yaw of the full pivot mechanism.

7.1.1.4 Torsion Spring System

Using the righting moments discussed in section 3.4.1, the group wanted to include a restoring force in the pivot mechanism. The decision was to use springs. These spring will help right the kayaker when the user is off balance. The force that each spring will need to push is 240lbf·in in which is found from 20lbf·ft * 12 /ft. When at 20° tilt, the pivot mechanism’s springs will be exerting 240lbf·in of force to right the user. A spring needed to give this force would have to be a relatively large spring. The two kinds of springs considered are the torsion spring and a compression spring. Due to the current pivot mechanism size and set up, it is easier to use a torsion spring. This spring however will have to be twice as large as an equivalent compression spring.

Figure 23 - Torsion Spring inside pivot mechanism assembly

24

The torsion spring set up is as follows. Two torsion springs are needed, one on each end of the roll shaft, in between the pivot support and the casing wall. Each spring will be supported from a pin pressed through the pivot supports and from a pin in the front or back walls of the casing. The springs installed so their actions counteract each other. The springs are installed minimizing slipping and attempting to reach the righting moment roll angle. Figure 24 shows the linear force of the Pisces ocean kayak as it reaches 20° of tilt. The torsion spring calculations are found in appendix E-8.

Linear moment on Pisces Ocean Kayak

300

250

200

Linear of Pisces Ocean 150 Kayak Lbf*in

100

50

0 0 5 10 15 20 25 Degrees of Heal

Figure 24 - Linear moment of roll springs

7.1.1.5 Compression Springs

The space requirements of the current pivot mechanism design led to the selection of torsion springs in this system. The calculated compression springs would have required the pivot mechanism casing to be 4 inches wider. Because the Concept II I-beam is the base the pivot mechanism is attached to, the design must be aware of the moments acting on the sides of the I- beam. The considered compression spring design was composed of a total of 4 springs. Two springs on each side, each taking half of the calculated necessary 240lbf*in load. The diameter 3 of the springs was 2- /16” and had a wire diameter of .25”. Each spring was 4“ long and can compress a total of 2.06” which will allow for a maximum required compression of 0.89”. The spring would have been held in place by forks that would allow the springs to compress but not move from the spot it needs to sit upon. The full calculations for the compression spring option can be found in Appendix E-9.

25 7.1.2 Cockpit

Figure 25 - Cockpit assembly The pivot mechanism’s cockpit is supposed to replicate the kayak’s cockpit. This includes the layout and the bracing. Figure 25 shows the layout of the cockpit design which can be compared to the components of the whitewater kayak in Figure 5. The cockpit is attached to the pivot mechanism yaw component through the flange. The center of the yaw shaft is near the center of the seat. Most of the kayaker’s weight will act directly down on the yaw shaft reach the pivot mechanism. For easy entrance to the cockpit, one of the thigh hooks supports folds down as shown in Figure 26. This thigh hook is supported by a pin during operation of the machine.

In the prototype, the platform and thigh hooks supports are made of wood. The seat and backrest use Concept II rowing machine seats. Ideally, the cockpit platform would either be made of a more solid wood platform or of a lighter strong material such as carbon fiber. The thigh hooks and side braces supports would be made of metal and the padding provided by better cushions instead of foam.

26

Figure 26 - Cockpit of prototype with folded down thigh hook support

7.2 Concept II Kayak Stroke Adaptor

In order to verify that the pivot mechanism and cockpit are reacting appropriately to kayaking upper body forces, the group determined that it would be necessary to put a Vermont Waterways Kayak Adaptor onto an existing Concept II rowing machine. While the group had access to a rowing machine for free, the Vermont Waterways adaptor cost $775. This cost was deemed to be too high for a part which would simply verify the function of the pivot mechanism. The group decided to build their own adaptor at a much lower cost. This adaptor approximates the upper body motion. In an ideal situation, our pivot mechanism adaptor would be used with a real kayaking machine.

27 Appendix G contains the parts list and the drawings of the upper body adaptor designed by the group. The adaptor is T- shaped bar clamped on to the concept II rowing machine’s I-beam. Each end of the vertical piece has rollers to guide the rope which is attached to the paddle piece. This rope is attached to the Concept II’s chain at the flywheel attachment through a series of pulleys and eyehooks. The Concept II’s chain is attached to the Concept II’s flywheel which will provide the upper body adaptor’s resistance. At the upper body adaptor’s flywheel attachment the rope to threaded through a hole and follows a similar set of pulleys and eyehooks to the Figure 27 - Picture of upper body adaptor on the other end of the paddle piece. concept II rowing machine

This version of the kayak upper body motion adaptor is not meant to replace the Vermont waterways kayak adaptor but merely to mimic kayaking strokes for short periods of time to verify the function of the pivot mechanism. No in depth calculations were completed for this part of the project. However, engineering steps were taken in this design. It was important to verify that the setup would work properly, the required force would be reduced and that the mechanism worked for purposes of testing the pivot mechanism. An example of this, the pulleys are setup to reduce the force 2 to 1 required to pull the concept II Chain from the fly wheel.

28 In practice the upper body adaptor as designed did not function as well as the group would have liked. The adaptor was made of wood instead of the desired metal. Because the adaptor must approximate the motion, and it is not critical to achieve perfect stroke form, it was reconfigured. A picture of the upper body adaptor as Figure 28 - Top view of upper body adaptor viewed from the cockpit can be seen in Figure 27 and a top view of the upper body adaptor is shown on Figure 28.

8 Cost Analysis

In order to perform the cost analysis on the group’s device, the design was been broken up into two parts, the design prototype and the testing prototype. The design prototype consists of the pivot mechanism and the cockpit. These parts are the bulk of the group’s project, and are essential to meet our requirements of a mechanism that allows the user to roll and yaw. Ideally, the design prototype would work with a Vermont Waterways Concept II kayak stroke adaptor (3.1.2). Due to cost and part availability the group was unable to acquire the adaptor. Testing using upper body reactions was still required in order to verify the function of the device prototype. This required the design of the upper body kayak stroke adaptor (section 7.2) which takes the place of the desired Vermont waterways adaptor, and is thus our testing prototype.

The total cost of all parts of the design prototype came to a total of $413.53. The built design prototype cost was $245.67. The total cost price is based on cost of the parts and materials, it does not include machining and labor costs. The current built prototype has many

29 parts recovered from the Capstone machine shop’s spare parts inventory; therefore the actual cost of the group’s prototype was lower. If the pivot mechanism was built in bulk, the part cost would drop and the device would be more affordable for the user.

The current market kayak ergometer market is very limited at the time. Machines are marketed to the competitive flatwater kayaker. Given the popularity of kayaking, and the growing number of participants in all different types of kayaking, the market for a kayak ergometer for off-season training is much larger than is currently represented.

Most current kayak ergometers are very expensive. The group’s design prototype is inexpensive in comparison to most base model kayak ergometers. A cost comparison of common kayak ergometers is shown in Table 2. When reading the table take notice that the Concept II rowing machine and the Vermont Waterways Kayak adaptor must both be purchased in order to achieve a kayak stroke motion.

Table 2 - Prices for currently available Ergometers Current Available Kayak Ergometers Dansprint $3,868 US Kayak Pro $2,000 US Concept II $850 US $775 US Vermont Waterways Adapter

The group’s pivot mechanism prototype could be easily modified to fit on any currently available kayak ergometers by changing the design of the attachment mechanism.

Most of the pivot mechanism was built from 6061 aluminum. The parts are designed to be easily machined and assembled. For example, #4-40 socket cap head screws were used throughout the pivot mechanism to avoid assembly confusion. The part list of both the pivot mechanism and the cockpit is found in Table 3. Further information about the parts and the cost can be found in Appendix H.

30 Table 3 - Parts list of both the pivot mechanism and the cockpit Parts List Pivot Seat Cockpit/Seat # Part Name Pieces # Part Name Pieces 1 Clamping Plates 2 1 seat 1 2 Casing Base 1 2 Leg Brace Support 2 3 Casing 4 3 Corner Bracket 2 4 Roll Shaft 1 4 leg Braces 2 5 Roll Bearing 2 5 back brace 1 6 Pivot Support 2 6 back brace bracket 1 6 Yaw block 1 7 Leg Brace Pins 2 7 Yaw Shaft 2 8 Bolts 12 8 Yaw Flange 1 9 Nuts 12 9 Yaw Bearing 2 10 hinge 1 10 Torsion Spring 2 11 Pin 1 11 Box pin 2 12 Leg Brace Brackets 2 12 Support Spring Pin 1 13 resin gallon 13 Screw (#4, 40) 22 14 linen 40 yards 14 tighten screws 2 15 Brace Bolts 2 16 Brace Nuts 2

Several parts were recovered from the machine shops spare parts, such as screws and metal plates used to machine parts of the pivot mechanism. Some parts had to be ordered to specification, such as springs and the bearing. Table 4 shows the parts that were purchased through the mechanical engineering department’s capstone project funding.

31 Table 4 - Parts purchased through school funding for prototype Item # Description QTY 1 Seat top w/screws kit (C) 1 2 Zinc plated Pulley (Double Sleave) 1 3 Zinc plated Pulley (Single Sleave) 2 4 8"x8" .5" thick Al Plate ASTM B221 1 5 Flanged open Bearing (5/8") 2 6 4" interroll Rollers 4 7 Inner Ring and Roller Assemby 1 8 Outer Ring (Bearing attachment) 1 9 Torsion spring 2 10 12"x12" 1/2" Al Block 1

Parts for the testing prototype were mostly purchased by group members at the local harware store. Several parts, such as rollers, pulleys and the concept II rower seat were ordered and are already listed in the tables.

9 Future improvements

Improvements could be made to the prototype model that the group did not have time to address during the duration of this project. Ideas include the incorporation of a resistance mechanism, brakes for the roll and yaw mechanisms, a more comfortable and adjustable cockpit, and a more solid attachment of the pivot mechanism to the I-beam.

9.1 Resistance mechanism

Earlier design concepts incorporated an adjustable resistance mechanism which would allow users of different weights to experience similar levels of resistance from the pivot mechanism. During the concept discussions ideas were discussed but most involved high wear parts that would restrict the fluid roll motion and would need to be replaced regularly.

32 The resistance mechanism would be adjustable, with low wear and minimal restriction on the roll or yaw motions. In addition a decision must be reached as to whether the both the roll and yaw mechanisms need resistance mechanisms.

9.2 Roll and yaw brakes

When the user is in the cockpit he or she should be able to stop the pivot mechanism’s motion in order to get out of the device. Being able to stop motion is an important safety feature. The primary design requirement for this device is an ability to stop motion along both the longitudinal and the normal axis without having the cockpit perfectly balanced. The user should not have to reach under the cockpit while they are already off balance.

9.3 User friendly cockpit

The cockpit should be improved to be more comfortable and more adjustable for the kayaker. The seat and backrest should be more ergonomically correct than that shown in the group’s prototype. To better approximate the different boats with different setup selected by different kayakers, the thigh hooks should be adjustable for different users. In addition, the design should incorporate a method for the kayaker to enter and exit easily.

9.4 Improved pivot mechanism attachment

The current pivot mechanism attachment relies on horizontal clamping to attach the pivot mechanism to the Concept II I-beam. A method of clamping through vertical pressure should be examined to prevent damage to the I-beam. When designing this, consideration should be taken for easy user attachment to the I-beam.

Attachment of the pivot mechanism to other kayak exercisers should also be examined to increase the potential market for the device. Attachments could be modified by changing the casing base and clamping mechanism to fit on different machines.

9.5 Restrict yaw range of motion

To improve the kayaker’s safety during operation of the group’s pivot mechanism, the range of motion of yaw should be limited. Creating a limit of 90° total or 45° left and right would prevent the kayaker from getting tangled in the upper body adaptor’s cords.

33 9.6 Kayaker improvement feedback

As the kayaker is training he or she will want to know if they are improving. Finding a method of quantifying the kayaker’s improvement in yaw motion and in balance would be useful in finding a method to demonstrate this feedback to the kayaker.

10 Conclusion

This project aimed to improve an already existing kayak machine. Through customer feedback and kayak kinematics, the group found that current kayak machines lack torso involvement and balance preparation. To improve these inadequacies, a pivot mechanism that allowed roll and yaw was designed. The user sits in a cockpit with thigh hooks and a backrest arranged like that of a kayak, this cockpit is attached to the pivot mechanism. Springs within the pivot mechanism provide restoring forces to the kayaker similar to the buoyancy force of water on a kayak. Due to an inability to acquire a kayak adaptor for a Concept II rower, the group had to create an adaptor that approximated the kayak motion. This adaptor provides the user with the mechanics of the kayak stroke. Together the pivot mechanism, cockpit and upper body adaptor transform a Concept II rowing machine into a full body kayaking workout.

34 Works Cited and Consulted

1. “Paddle Sport Training Equipment, by Vermont Waterways”, http://www.paddlemachine.com/ [Jan 10th, 2006]

2. “Flight dynamics”, http://en.wikipedia.org/wiki/Flight_dynamics [January 26, 2006]

3. “Isometric Exercise”, http://en.wikipedia.org/wiki/Isometric_exercise [February 3rd, 2006]

4. “KayakPro SpeedStroke Kayak Ergometer”, http://www.speedstroke.com/, [February 27, 2006]

5. “Dansprint Ergometer”, http://www.dansprint.com/1/1/kayak_ergometer.html, [February 27, 2006]

6. “Concept II rowing machine”, http://www.concept2.com/ [February 27, 2006]

7. SeaKayak. “Section 12: How to make your Kayak go,” http://www.seakayak.ws/kayak/kayak.nsf/NavigationList/NT000032EE [April 13, 2006]

8. Outdoor play, http://www.outdoorplay.com/ [April 13, 2006]

9. Sisson Kayak, “Evolution Extreme”, http://www.sissonkayaks.co.nz/evoextreme.htm [April 13, 2006]

10. Schade, Nick, “Kayak stability and leaning”, http://www.guillemot- kayaks.com/Design/StabilityArticle.html [April 14, 2006]

35 11. “Review of the Mariner XL” Seakayaker, Spring 1987, http://www.marinerkayaks.com/mkhtml/xlrvtxtw.htm [April 14, 2006]

12. McMaster-Carr. http://www.mcmaster.com/ [April 16, 2006]

13. ABC-of-fitness.com. “How muscles work”. http://www.abc-of-fitness.com/fitness- basics/how-muscles-work,asp [April 17, 2006]

36 Appendix A

Appendix A - Kayaker survey

Hi, my name is Miriam and I'm an engineering student in Boston. I'm currently working on a group engineering project that involves an indoor kayaking exerciser. Now having grown up as a competitive rower I don't fully understand the wants and needs of real life paddlers, so I would appreciate if people would help me by filling out a little survey. You can reply by e-mail at [email protected]. Any help would be greatly appreciated.

All questions are optional. Feel free to add additional information as you see fit.

Location: Contact Information:

1. How often do you kayak? 2. What type of kayaking do you do (ocean, river, lake)? Do you do so competitively? 3. In your opinion is kayaking a good source of exercise? How often/long do you kayak for? 4. How do you currently train for kayaking in the off-season? 5. Have you ever used an exercise machine designed for kayaking? If so, what did you think of it? 6. If there was a kayak machine available to you, would you use it? 7. What kind of features would you see as being important in said machine?

Thanks Mir

Northeastern University A-1 Capstone 2 MIME Department Appendix B

Appendix B - Kayaker Feedback

The nature of the project required gathering information from potential users. A vibrant kayaking community was reached through several internet discussion forums. Our primary resources where the livejournal kayaking community, the yahoo groups kayak and kayak_club, the discussion board at paddling.net and the Northeast Paddler message board (http://www.npbm.com). Members of the message board were asked to fill out a survey to help us gather information about the wants and desires of current kayakers. A sample of this survey can be found in Appendix A. The survey in general asks interviewees about their involvement in kayaking, how they feel about the exercise benefits of kayaking, if they have ever used a currently available machine and what features they would like to see in a kayaking machine.

The interviewed kayakers came from all over the world and were involved in kayaking at different levels. We had weekend ocean kayakers as well as ex-US National Flat-water Team members. Each interviewee had separate visions of what the machine should be focused on and what features would be essential. Of 22 responses with useful suggestions for development of a machine, 12 had used some kind of kayak machine in the past. These machines included the Dansprint, the K1 Ergo, the Speedstroke Pro, Strength simulating machines, the concept 2 adaptor, the PaddlePro, Stairmaster Crosstrainer 2659 Kayak Rowing Machine, as well as unspecified models. Kayaking as an exercise also brought several different opinions.

Kayaking as an exercise

Most kayakers interviewed agreed that kayaking has some physical benefits to the body, although they do not always agree on the effect. We found that most kayakers think their sport is an excellent core workout. Many sea kayakers don’t always find the cardio to be a primary aspect of the sport. Bob G, non competitive ocean kayaker, said “it is more of an endurance type stroke than a workout intensive stroke.” Mike H, ocean kayaker, pointed out in his survey that the cardio workout comes mostly from the torso involvement because “you cannot get up to aerobic rates with just your arms.” The use of the arms, especially to people with weak legs was mentioned as a good aspect of the exercise by Doug F, ocean kayaker, “it is an excellent aerobic exercise for the

Northeastern University B-1 Capstone 2 MIME Department Appendix B

upper body in particular. No impact and you can pretty much go at your own pace.” John H, competitive sprint kayaker with Olympic aspirations and sports performance coach with an MS in kinesiology, mentions that kayaking “requires a solid base of endurance and strength.” From these responses, we can establish that our machine should incorporate the torso motion in order to allow for cardiopulmonary effects.

Uses for a Kayaking machine

Different kayakers had different views on what a kayaking machine would be used for in their lives. Some people surveyed had already tried available machines and were seeking something else from our machine, or improvements on current machines. Others had never seen the current kayak machines, so we were able to see the basic requirements of some kayakers.

Improve balance Real kayaks require the user to balance a boat as they move through different water conditions. A machine that could work the balance aspects of the boat would allow them train the small muscles that coordinate a kayaker’s motion in the boat. Three of our respondents with experience with kayak ergos or 25% of them mention that balance would be an interesting feature. Kate D who has never used a kayak ergo, suggested making a machine that simulates “surf conditions to train reflexes for bracing and rolling.” Kari H, competitive ocean kayaker who has used a KayakPro in the past, mentions that it would be nice if the machine’s “balance and tipiness is adjustable for different people.” When asked about the balance aspect, Sean B, a former US National team member told us that when he “was at the training center we discussed putting a balance aspect into the ergo, but it was deemed not cost effective.”

Physical therapy tool Kayakers recovering from rotator cuff injury such as a whitewater kayaker who communicated through livejournal could use a machine to help with the recovery process. This machine would help prepare them to get back out on the water and reduce the risk of reinjury.

Northeastern University B-2 Capstone 2 MIME Department Appendix B

Strengthen specific muscles The kayak machine should strengthen the muscles used in kayaking, the whitewater kayaker mentioned in the previous point mentioned “strengthening my front shoulder muscles to prevent dislocations and strengthening stomach muscles.” Kate D, ocean kayaker, mentions that the machine should “strengthen all the abs, lats, lower spine and muscles for torso rotation, and hips to edge the boat.”

Keep legs limber Although kayaking maintains an appearance of upper body motion, there is an involvement of the lower limbs. Kim P, ocean kayaker, thought the “involvement of the lower body” was important, as “the kayak stroke utilizes the torso, rotating over the hips and braced by the feet and knees.”

Cardio workout While some kayakers surveyed felt the machine should be more of a strength workout, others praised the cardio aspects a machine should incorporate. The use of torso rotation is essential in raising the heart rate of the users.

Improve technique A machine that would encourage good technique could be very useful to help novice and veteran users learn and maintain good form in the off-season. Kate D, ocean kayaker who has never tried a kayaking machine, mentioned that many kayakers experience “epicondylitis and wrist tendonitis” due to improper technique. One kayaker, from northern California said they would like a machine that gives “exact mimicry of the perfect stroke.”

Features of a machine

Through the surveys we requested information about what features the kayakers would like to see in a machine. The general aspects requested in the interviews are outlined below.

Inexpensive Current machines can cost over a thousand dollars. Several kayakers mentioned that this is too expensive for them. Cal S, a competitive kayaker, mentioned that he “cannot justify spending Northeastern University B-3 Capstone 2 MIME Department Appendix B

$1400 for a KayakPro” because he can “buy a good used boat for that much.” Kayakers who provided cost feedback mentioned that a machine would have to cost less than a thousand dollars for it to spark their interest.

Easy Maintenance Cal S, also mentioned in this survey that the machine should be “easy to maintain or repair.” This would mean that the consumer would be able to repair small problems with the machine themselves, reducing the time where the machine sits unused. The machine would also be durable to reduce the amount of downtime experienced by the user.

Movable The machine should be light enough that it can be moved into storage easily and by one person. Michael S, Lake Kayaker, says that the machine should be “collapsible for storage.”

Adjustable The machine should be adjustable to different persons’ sizes and resistance preferences. Mike M, recreational flatwater kayaker who has used the Dansprint and the Speedstroke, mentions that “the [display] should be positioned so it is visible when looking straight ahead.” With the different height of athletes, the computer would have to be movable so it could be seen from different angles. In addition, Don K, ocean kayaker, felt that the machine should have “the ability to conform to your style of stroke (ie. Ability to simulate a high angle stroke or low angle stroke, sweep stroke, etc).”

Similar position to real kayak In order to replicate a kayak, the machine should encourage it’s users to sit in a similar position to a real kayak. Mike M. says that “the seating and footrest position should be similar to a real kayak.” Bill S. mentioned that the machine should “not develop muscles that aren’t involved in real kayaking.”

Northeastern University B-4 Capstone 2 MIME Department Appendix B

Max resistance at catch An important aspect of simulating real kayak stroke is to get the resistance at the right point of the motion. Mike M. explained that “the greatest resisting force should be at the catch not at the back of the stroke.”

Smooth resistance John D., competitive ocean kayaker who was not impressed with the kayak exerciser he has tried, thinks the machine should have “a similar feel and resistance versus speed to real kayaks.” Some currently available machines have been accused of being jerky, the real kayak stroke being a very smooth motion.

Computer An important part mentioned in interviews is feedback. A computer on board the machine would inform the user about several aspects of his or her performance and therefore motivate them to continue working out. John D., mentions that a “speedometer and heart rate monitor” would be essential. Darrell P. said he would like a computer to have “pace, average speed, top speed, and the ability to setup and time race distances.”

Opinions on currently available machines

Several kayakers interviewed had already used the machines that are currently available. Some provided us with feedback of their opinions on the machine.

KayakPro Speedstroke According to their website, the KayakPro Speedstroke was the official kayak ergo of the 2004 summer Olympic Games. It is currently used by several National Kayak teams. Competitive kayakers are generally quite pleased with the Speedstroke. John H., competitive kayaker, says “it has a very good feeling that is very similar to the water… many of the other ergs on the market are very harsh or jerky. The software available is also wonderful and helps with the training of serious athletes.” Kari H. also enjoyed the machine expressing that “the torso rotation it allows as a machine with adjustable resistance is great.” She does express however, that “it would be great

Northeastern University B-5 Capstone 2 MIME Department Appendix B

if there was such a thing that included the need to balance, as the Olympic flat-water style boats also require this.”

PaddleOne The PaddleOne has gotten mixed reviews. Cal S., competitive kayaker, feels that the PaddleOne machine “is a very poor excuse for a commercial machine.” Although the PaddleOne website cites Richard Dober Jr, a Canadian kayaking Olympian as saying “the PaddleOne machine is an essential tool to maintain good technique especially during the winter and also through out the year. Furthermore, It permits me to perfect my technique by providing both a stable and comparable environment to the one on the water.” A member of the paddling.net discussion forum likes his PaddleOne, stating that “it took a little time to get used to the precise motion to have to do to adequately simulate kayaking. It’s very compact too.”

Concept II Adaptor The concept II adaptor takes a regular rowing ergometer and converts it into a kayaking machine that generally resembles the Speedstroke in pictures. Cal S. feels that it’s a great machine, but requires more strengthening of the core muscles. He also says that our machine should be “longer than the concept 2 so the top hand doesn’t get pulled down.”

K1 Ergo The K1 Ergo is an Australian machine that has to be imported into the United States. Only one person interviewed that ever used one. Sanjay G. said that “it is quite similar to the Kayak Pro. It has a harder catch (i.e. when the blade first enters the water). It is perhaps not quite as nicely made overall, but I’ve had mine for 8 years now and not major problems.

Northeastern University B-6 Capstone 2 MIME Department Appendix C

Appendix C - Biomechanical Analysis

This appendix contains the handwritten calculations for the biomechanical analysis. Force down on the seat from mechanism C-2 Forces on the feet C-4 Forces on the legs C-5 Forces on the thighs C-6 Forces on hand C-8 Forces on forearm C-9 Forces on upper arm C-10

Northeastern University C-1 Capstone 2 MIME Department Appendix D

Appendix D - Types of Kayak

Example of a Flatwater Racing Kayak

Figure 29 - Flatwater Racing Kayak Evolution Extreme [9]

LENGTH WIDTH COCKPIT WEIGHT PADDLER 19.5” 17” 23” x 15” 35.3 lb 220 lb

Northeastern University D-1 Capstone 2 MIME Department Appendix D

Example of Ocean Kayak

Figure 30 – Ocean Kayak Specter 14.0 w/ Rudder [8]

LENGTH WIDTH COCKPIT WEIGHT PADDLER

14'2" 24.25" 35" x 18.5" 58 lbs. < 285 lbs.

Northeastern University D-2 Capstone 2 MIME Department Appendix D

Example of Whitewater Kayak

Figure 31 - Whitewater Kayak Rx 6.9 [8]

LENGTH WIDTH COCKPIT WEIGHT VOLUME PADDLER

6'9" 26.25" 34.75" x 19" 35 lbs. 58 gals. 150 - 225 lbs.

Northeastern University D-3 Capstone 2 MIME Department Appendix F

Appendix E - Material Calculations

Lifetime cycles of pivot mechanism E-2 Cockpit mass and center of mass E-3 Yolk force distribution E-5 Pivot mechanism shaft diameter E-6 Roll bearing calculation E-8 Determination of yaw shaft diameter E-9

Northeastern University E-1 Capstone 2 MIME Department Appendix F

E-1 – Number of Strokes in Device’s Lifetime

Northeastern University E-2 Capstone 2 MIME Department Appendix F

E-2 – Cockpit mass and center of gravity calculations

Northeastern University E-3 Capstone 2 MIME Department Appendix F

Northeastern University E-4 Capstone 2 MIME Department Appendix F

E-3 - Distribution of the Loads on the pivot supports

Northeastern University E-5 Capstone 2 MIME Department Appendix F

E-4 – Pivot mechanism shaft diameter

Northeastern University E-6 Capstone 2 MIME Department Appendix F

Northeastern University E-7 Capstone 2 MIME Department Appendix F

E-5 – Roll bearing calculations

Northeastern University E-8 Capstone 2 MIME Department Appendix F

E-6 – Determination of yaw shaft diameter

Northeastern University E-9 Capstone 2 MIME Department Appendix F

E-7 - Pivot mechanism screw calculations

Northeastern University E-10 Capstone 2 MIME Department Appendix F

Northeastern University E-11 Capstone 2 MIME Department Appendix F

E-8 – Torsion Spring calculations

Northeastern University E-12 Capstone 2 MIME Department Appendix F

E-9 - Compression spring calculations

Northeastern University E-13 Capstone 2 MIME Department Appendix F

Appendix F – Pivot Mechanism and cockpit drawings

This appendix contains the drawings for the pivot mechanism and cockpit designs.

Pivot Mechanism with attachment bill of materials F-2 Casing base F-3 Clamping plate F-4 Yaw Block F-5 Pivot Support F-6 Roll shaft F-7 Front and back casing wall F-8 Side casing walls F-9 Yaw shaft F-10 Yaw Flange F-11 Cockpit setup F-12

Northeastern University F-1 Capstone 2 MIME Department Appendix G

Appendix G – Upper Body Adaptor

This appendix contains the parts list and drawings for the upper body adaptor.

Parts list memo G-2 Upper body assembly drawing G-3 Side of roller drawing G-4 Bottom of roller drawing G-5 Pulley plate drawing G-6 Main beam drawing G-7 Top spacer drawing G-8 Bracket drawing G-9 Bottom spacer drawing G-10

Northeastern University G-1 Capstone 2 MIME Department Appendix H

Appendix H – Cost Analysis

Item Part cost Total # QTY Number Description each cost Notes Supplier/Vender 1 1 1703 Seat top w/screws kit (C) $11.10 $11.10 cost w/out shipping $6.00 Concept II 2 1 3099T44 Zinc plated Pulley (Double Sleave) $9.18 $9.18 McMaster 3 2 3099T34 Zinc plated Pulley (Single Sleave) $5.46 $10.92 McMaster 4 1 9246K31 8"x8" .5" thick Al Plate ASTM B221 $22.93 $22.93 McMaster 5 2 6383K247 Flanged open Bearing (5/8") $7.24 $14.48 Roll mech McMaster 6 4 9851817 4" interroll Rollers $6.63 $26.52 MSC Direct 7 1 23915T11 Inner Ring and Roller Assemby $22.85 $22.85 yaw mech McMaster 8 1 23915T71 Outer Ring (Bearing attachment) $9.38 $9.38 yaw mech 9 2 9271K127 Torsion spring $5.90 $11.80 McMaster 10 1 9246K13 12"x12" 1/2" Al Block $25.93 $25.93 roll mech McMaster 11 4 4358 2" x 4" x 96" wood platform $2.78 $11.12 Cockpit and upperbody mech Home Depot

Northeastern University H-1 Capstone 2 MIME Department