Gino Morrelli Explains: The Velocity Prediction Program May/June 2015

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by Gino Morrelli [email protected]

What the Heck is a VPP?!

ne of our new clients was hanging out at our which is from our new Morrelli & Melvin-designed design office the other day, while we were Rapido 60 trimaran – www.Rapidotrimarans.com). Oenthusiastically debating the minutiae of Magazines typically print these crazy intimidating one “VPP” versus another. In a brief break, he quietly circular rings without explanation! They are basi- asked me “What the heck is a VPP?” It was then I cally displaying the vessels boat speed at different came to realize that not everyone, even experienced True Wind Speeds (TWS) (2-25 knots) over a range owners, may completely understand just what a VPP of True Wind Angles (TWA) (0-180 degrees). Each is and why it’s so useful for designers and sailors. squiggly line on the diagram represents a particular VPP stands for Velocity Prediction Program. It’s sail combination, like Full Main Sail and Jib or Full typically a computer program that most yacht design- Main Sail and Reacher, etc. Multiple sail configura- ers covet and protect to help figure out how fast a boat tions/lines can be overlaid on the same Polar Dia- will go. Normally, for multihull sailboats, we enter gram and you can see where the lines “Crossover.” in the basic parameters of a given boat, like length, displacement, hull beam, wetted area, rig parameters, Crossovers: individual sail areas, etc... and it spits out a matrix of For an owner, these “Crossovers” help predict when boat speeds for each combination of True Wind Speed you should change sails as you go from upwind to (TWS) and True Wind Angle (TWA). In the case of the reaching or downwind, in different wind speeds. latest high performance ’s Cup VPPs, we upload We can tell the VPP program maximum Apparent the actual 3D hull models with boards and rudders. Wind Speeds (AWS), any sail can operate in, helping We started building our first primitive computer- you not break a sail or push it past its recommended ized VPPs during the 1988 America’s Cup with Clay limits. So, if you’re rounding a point or a mark you Oliver and SAIC for Dennis Conners’ successful can look at the Polar Diagram and predict with bet- , the first 60-foot wing sailed cat Stars and ter confidence what sail you’ll want to set next, sav- Stripes. We were just trying to accurately predict ing energy or possibly damage by setting the wrong hull flying wind speeds and apparent wind angles. sail for the combination of True Wind Angle/Speed. As time went by, we kept Clay busy upgrading our version of his commercially available VPP with cus- Holes in Your Sail Wardrobe: tomizable inputs and outputs. During the last two Cup The VPP output, when given to a sailmaker, can campaigns (BMW/Oracle Trimaran in 2010, ETNZ assist him in building sails that work best within the AC72 cat in 2013), we were involved with develop- apparent wind angles predicted, so the sail is not built ing even more sophisticated versions that helped us too full or too flat. There is a bit of give and take develop the fully flying AC72s that we saw blasting between the owner and sailmakers in deciding on around in San Francisco fully flying on ! the Apparent Wind Speed (AWS) limits of any given sail, especially reachers and spinnakers. Sailmakers Polar Diagrams: want to divide this into small ranges and sell you more The output from a VPP is typically presented in what’s sails to improve performance for every wind angle called a “Polar Diagram.” (See the diagram on page 24, and speed! A good VPP provides guidance in finding

24 MULTIHULLS Magazine | May/June 2015 a good compromise on the number of sails, their prediction. In addition, each element: sail coefficients, respective Apparent Wind speed/Wind angle limits wave drag theory, efficiency of dagger boards/rudders easier so as to avoid “Holes” in your sail wardrobe. – all affect speed. So getting all of these formulas to balance and accurately reflect reality is easier said than Steering/Trimming Performance: done – and is what determines the quality of the propri- On many modern boats with wind instruments, you etary VPP tools that a boat designer develops, through can upload your VPP output into the onboard computer. experience, over time. Accurate data, fed into a mature, Then while sailing you can select “% of Polar” on your well-tested VPP program, does produce predictions that instruments and compare how you are doing versus quite accurately reflect expected performance. theoretical. It’s a good way to gauge how you are sailing, So, VPP programs can be very useful to all concerned. day-to-day – or especially at night when it’s very tough As designers – we use proprietary VPPs that we have at times to gauge if your trim is off. This gives you an developed over the years to test our design decisions. objective benchmark to compare against. On race boats, We experiment with different combinations of hulls, as each helmsman comes off the wheel, he can go to rigs, beam, dagger board styles (curved Cs vs. straight) the navigator and receive a “Report Card,” telling him vs. mini keels, etc., to optimize our designs, over the that for his period of driving, he sailed “XX% of Polar” widest range of conditions. As buyers – if you are out – helping to assess the actual level of his performance. shopping and comparing boats, you might want to use published VPP results as an essential part of your deci- Comparing Boats... Maybe: sion criteria, but take it with a grain of salt. As owners VPPs are a bit of a house of cards. As with any com- – VPPs are not something you need to own, but their puter program, VPPs suffer from “Garbage in – Garbage information can improve your sailing performance, out.” For example – if a boats displacement is modeled and reduce some of the guess work in choosing which as unrealistically light, then the VPP will give too fast a sails to use in any given conditions.

www.multihullsmag.com | MULTIHULLS Magazine 25 VELOCITY PREDICTION PROGRAM | POLAR DIAGRAM RAPIDO 60 TRIMARAN | WWW.RAPIDOTRIMARANS.COM

WIND DIRECTION

10 20 30 40 50 60

TRUE 70 WIND 20 ANGLE (DEGREES) 14 80 10 6 BOAT SPEED 4 6 8 10 12 14 16 18 20 22 24 26 28 (KNOTS) 6 B 10 6 14 100 10

14 A 110 20

20 120

160170 150 140 130

LEGEND

10 TRUE WIND SPEED (KNOTS)

JIB + MAIN

REACHER + MAIN

SPINNAKER + MAIN

POINT OF OPTIMUM VMG

A POINT SHOWING BOAT SPEED OF 26.5 KNOTS @ 110° TWA, 20 KNOTS TWS WITH REACHER + MAIN

B CROSSOVER POINT

26 MULTIHULLS Magazine | May/June 2015

Company Spotlight by Paul Hakes [email protected] Boat Building in China – Part 5 Assembly & The Production Line

e continue to witness boats on the go, production plan- for many years – PROFIT; it seems the fruition and pay- ning and coordinating with sales this word is not used regularly by Wback of well-detailed and design is critical. We look at boat builders as they worry about design, good planning and clever the special care taken to identify the idea of owners seeking further tooling. This month we can see design and production issues en- discount or a better deal elsewhere assembly advancing well on boat countered with HH66-01 and how if they are seen to make a profit HH66-01, which we will look at we feed this information back into from yacht construction, an ob- in more detail. We will also now the design and production planning vious mistake when we all know take a look at our production line departments to eliminate any er- a company must make money to as we see HH66-02 emerge from rors being repeated. In looking at survive. For sure, we are blinded the molds and undergo stage 1 our production, I will talk about a at times by our passion to build assembly, and HH66-03 start the word that has been treated as “Roy- wonderful sailing or power boats, lamination process. With three al Taboo” amongst boat builders and the romance of building such

The giant carbon fiber port topside and sidedeck molding is moved into position.

28 MULTIHULLS Magazine | May/June 2015 The production line emerges with Hull 01 in the background Hull 02 in front and hull 03 in the lamianting clean room behind them both.

epically beautiful man-made cre- are complete, air conditioning getting our workers to think about ations often clouds our clarity that conduits complete, black/grey the small details that were to oc- the necessity of the business is that fresh and saltwater systems all in, cur, like: how a hose clamp should we must be profitable. tanks all connected, diesel transfer be orientated – is the hose clamp HH66-01 has undergone a re- pumps and bilge pumps all in place. orientated correctly to be able to markable transition that is set to Rather a lot to preplan and install access at a later date? Are there continue for the next month; the at this early stage and only possible spare wires pulled into the wire topsides, which include the side with well executed systems design. looms for the small pieces of equip- decks, have been fitted and bonded. Small problems encountered were ment requested at the last minute? At la st we get to appre ciat e t he t r ue size of this beast and the spaces contained within. In the first hull, the client has opted for the port hull to be a dedicated owners hull (no guest rooms), and so it is grand and palatial in its size. Still the spaces within the starboard hull are equal- ly impressive with two staterooms, each with separate large showers and bathrooms. The topsides being bonded were held off from being attached until we felt all systems were as far advanced as possible, this means all systems under the High strength epoxy adhesive is applied on all glue surfaces prior to the big bonding. soles are fitted out; wiring looms www.multihullsmag.com | MULTIHULLS Magazine 29 The furniture department love to do the same job again, sadly with the ability to make a profit is also ready. They have all sometimes on the same boat (this constructing this product? We will the furniture built, and is called rework – a profit killer!). not know for sure until the first waiting for first coats of Once the workers have mastered boat is handed over to its proud varnish. Indeed, we had to a task they look to make it easier, owner, but we can track costs us- remember to place some reduce the work load and find the ing our barcode and ERP systems units in the hulls prior to efficiencies. So we see the same to know ahead of time if we have bonding the topsides, as laminators installing the tank problems, and we can maximize t hey w ill not fit dow n t he grounds for all eight tanks into our chances of a good financial out- hatches. Next in a fast HH66-02, and building the hulls come by minimizing the profit kill- sequence will be the aft and wing-deck, bulkheads and ers. The boat must be designed and transom steps and cabin topsides for HH66-03. In the HH built to minimize warranty costs, top getting installed to furniture department which means maximizing reli- complete the bulk of they are now constructing the join- ability through quality design and the primary structure. ery for HH66-02. building, this is of course priority With such good So it seems the production line from a safety point of view as well progress on HH66-01, has switched nicely from our previ- as a business one. Then minimize a close eye on the pro- ous carbon catamaran to our new rework; ensuring the clients likes duction line is needed flagsh ip ya cht. T he ma nu fa ct u r i ng and dislikes, wants, and variations to en su re a dequ ate re - process is happening; jobs are be- are handled professionally; this is sources are applied to ing executed to plan, to the right a $3.5m yacht, the owner wants Hull 02 and now Hull qualit y, and in the r ight order. Cor- to input his or her own personal 03. This also means rect this is boat building…after all, styles and unique options, which the same resource this is meant to be the easy part, as have to be processed through an that has done the job we are boat builders! BUT are we efficient channel into the finished before! Our workers a good manufacturing business, product. Any misunderstandings

The port side and the palatial volume of the owners hull.

30 MULTIHULLS Magazine | May/June 2015 Hull 02 is out of the mold and well into Stage 1 assembly with tank grounds and piping routes be fitted. with the client, or assumptions manufacturing is no different. As sories, which are big projects in made by the sales team can lead we know the boat building indus- themselves. The 26m masts and to costly rework. Then there are try as a whole has been through 6m long daggerboards will be de- the design and production mishaps, a number of very hard financial sign and construction composite which mean rework and doing the years, a successful boat yard will ma ste r pieces when fi n ished , so we job twice. The first corrective ac- let passion drive its desire to build need a closer look. We will also tion is ensuring the information of great yachts, but keep a clear head take a spot check on a business a problem gets back to the design about the reality of organizing a level at t he H H Cat a ma r a n project , engineers, so that the alterations profit able ma nu fa ct u r i ng bu si ness. and understand where we are do- are made to the drawings and er- Our next article will cover both ing well or not, and what should rors are not repeated. The second the passion and the business. We a multinational multicultural large problem area is human mistakes w ill cont i nue to see H H66 - 01 g row yacht manufacturing business do while building – generally attrib- inside and out, and we will take a to ensure it is maximizing longev- uted to only three things going look at the appendages and acces- ity and financial success. MM wrong: equipment, information (including training) or materials. Success, fitted and glued... It is management’s job to supply Next is secondary bonding inside and these three key ingredients to its out to take the join to full strength manufacturing workforce mini- mizing rework. These are some of the challenges any and all businesses must face to do well, the objective of any growing business is to maximize ROI and profitability and yacht www.multihullsmag.com | MULTIHULLS Magazine 31