SYSTEMS Part 1: Mechanical Systems

Installation and maintenance of cable, jacketed-cable, and geared steering systems begin our two-part series.

Text and photographs by Steve D’Antonio

fter sail or engine propulsion, steering is one of the most majority of cruising sailboats less than 60' (18.3 m) and some A important systems on any . In the systems inspec- power vessels. tions I conduct, I mark a deficiency as a critical or important safety item if the answer is “yes” to any of the following Cable over Sheave questions: Will a failure of this component cause the vessel The fundamentals of the system are straightforward to flood? Will it cause a fire? Will it injure a crew member? enough. Beginning at the helm, a chain sprocket more robust Will it cause or lead to a loss of steering or control? than the one on a bicycle is attached to the wheel’s shaft. Over Multiple steering systems have evolved over the past few this sprocket a chain, preferably stainless steel, is laid, and to centuries, the most basic of which, the and tiller, is each end of the chain (which may be 2'– 4'/0.6m –1.2m long still used today. I remember as a boy sitting in the -facing or more, depending upon how many turns the wheel makes seat of our family’s 16' (4.9m) runabout marveling at the fully from hard over to hard over) a stainless-steel-wire cable is exposed “clothesline” cable-and-pulley steering system. The attached. The cables travel, with the aid of sheaves to guide cable would periodically jump off the drum, requiring my and turn them, to engage a quadrant attached to the rudder father or brother (and then me when I was older) to slacken shaft. Thus, when the wheel is turned, the sprocket acts on the the whole system, rereeve it, and then tension everything up chain, which pulls on one side of the cable, which in turn again. Such episodes taught me the value of a reliable steering places tension on the quadrant, causing the rudder to turn. system, especially when a failure occurred during vigorous While this may sound complicated, it’s quite simple. In maneuvering, typically when docking. fact, the rugged simplicity of the cable-over-sheave steering A variation on this cable-over-sheave system, sometimes system is one of its greatest attributes. When properly referred to as chain-and-wire, is still used aboard the vast designed, installed, and maintained, these systems rarely fail.

Above—The best defense against mechanical steering system failures is regular inspections. On this pedestal-mounted cable- steering installation, at least the chain and helm sprocket are quite accessible.

20 Professional BoatBuilder Above left—This standard cable-over-sheave quadrant is partially installed. In service, the quadrant must be protected from any stored items, while being easy to reach for inspection and repair. Above right—The chain-and-sprocket assembly of this cable system runs close to multiple electrical components, which must be secured or physically isolated to prevent chafe. Right—This cable-over-sheave chain succumbed to crevice corrosion that grew from microcracking caused by the stresses of neglect or overtensioning. Thoroughly grease and sprockets, and every few years wash them in solvent such as kerosene before renewing the grease.

And when they do, they lend themselves very well to emer- Above all else, cable-over-sheave systems must be prop- gency repairs. Most failures involve parted cables or broken erly specified and sized for the application. If the system is chains. The prudent skipper of a vessel equipped with such not right for the vessel in which it’s installed, its reliability a system will keep a properly sized chain-and-cable assem- and performance will be far from certain. Builders and refit bly in his or her spares locker. At the least, a length of wire yards should collaborate closely with steering system manu- cable and several bulldog clamps should be kept on hand to facturers to ensure a proper match. jury-splice a parted cable. The system must also be correctly installed. Of all the deficiencies I’ve found in cable- over-sheave steering-system installations, misalignment is among the most common. If the cable is not properly aligned with the various sheaves and the quadrant over which it turns, then the performance of the sys- tem, as well as the longevity of the cable itself, will suffer.

Precise cable-routing through multiple turning blocks is critical. If cables don’t lie in the center of the sheave’s groove, both will wear prematurely.

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Left—Broken wire strands, or “meat hooks,” are a clear sign that a cable should be replaced. Even one broken strand is too many. Right—Another reason to be particular about leads is that where they unintentionally contact hose, electrical wiring, or wood, steering cables effectively become cutting tools.

An imaginary line drawn between composite, or aluminum sheave. If commonly terminated in one of two any two sheaves, as well as lines drawn allowed to persist, it will lead to a fail- ways: using either a wire rope clamp, between the sheaves and the quadrant, ure of one or more components. sometimes referred to as a bulldog must be perpendicular to the axle of It’s also important to note that clamp, or a permanently installed the sheaves and rudder shaft. If the bronze components, such as sheaves compression sleeve fitting, often cable is not centered in the sheave and and quadrants, should not be used referred to by the name of a popular the quadrant grooves, it will drag on aboard aluminum-alloy vessels. manufacturer of these products, these components. Builders should Because of galvanic incompatibility, Nicopress. pay careful attention to sheave place- the smallest particles of bronze dust Bulldog clamps (use only stainless- ment and installation (articulating will often lead to corrosion when they steel alloy clamps, preferably 316 in sheaves make this chore considerably come into contact with aluminum wet locations, and forged is preferable easier), which sometimes requires plating or other structures. Aluminum to cast) are reusable but frequently shims or custom brackets. If, for vessels should utilize only aluminum, installed incorrectly. The cable “turn- instance, metal dust or tiny shavings composite, or stainless-steel cable- back”—the distance the cable is paral- are found beneath a sheave, it’s often a over-sheave steering components. leled against itself and where the sign of poor alignment: each time the Cable terminations and quadrants clamps are installed—is a function of wheel is moved, the stainless-steel also frequently suffer from improper the cable’s diameter. For instance, 3⁄16" cable saws away at the bronze, installation. Cables in this system are (4.76mm) cable calls for a 3.75"

Left—Wire rope, or “bulldog,” clamps must be installed in only one orientation, with the “live,” or tensioned, portion of the cable retained in the clamp saddle, as illustrated here. Right—A cable should never be joined to a chain or quadrant without the benefit of a thimble to an appropriate radius in the wire and bear any chafe between the working components. Note that wire clamps should be stainless steel. The galvanized mild-steel ones, shown here, are beginning to rust.

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August/September 2018 23 SYSTEMS: Steering, Part 1

(95.25mm) turnback, while ¼" Left—This well-executed (6.35mm) cable calls for a 4.25" chain-to-cable transition uses (107.95mm) turnback. The sad- a Nicopress clamp to fix the dle, or open, end of the clamp cable eye. Below left—Take- up eyes are a cable-over- should bear on the loaded or sheave system’s fine-tension “live” portion of the cable (the adjustment. The eye position mnemonic is “never saddle a should be locked with double dead horse,” the dead end of the nuts, as shown here, as well cable being the portion not as by a single nut (not visible) under load). A minimum of two on the other side of the clamps, as well as a chafe-reduc- quadrant-attachment point ing thimble, must be used on to prevent any eye move- every cable termination. Install ment. The lower structure attached to this rudderstock the first clamp within a mini- is a tiller arm, to which an mum of one-clamp-base width autopilot ram will be attached. (approximately 1"/25mm) from the bitter end of the cable. The second should be installed as close to the thimble as possible one on the other side—that without impinging upon it, with are designed to be locked no slack between the two. against each other. Nut Torque requirements are a installation and location are function of the clamp’s size. For critical to lock the adjust- 3 instance, ⁄16" clamps call for 7.5 ment and to prevent move- ft-lbs (10.2 Nm); while ¼" clamps ment of the eye’s shank. require 15 ft-lbs (20.3 Nm). The quadrant is the sole Additional torque and installa- means of connection with, tion instructions are available on and application of torque to, clamp manufacturer websites. the rudderstock. The stock The clamp’s nuts should be alter- is the metal post that forms nately tightened to reach the the backbone of the rud- required tension. Heat-shrink der’s internal support struc- tubing applied to the bitter end ture, beginning within the of the cable will prevent fraying rudder blade and ending and nasty jabs when working in inside the boat. If the quad- this area. rant is not properly inter- Compression fittings utilize faced with the rudderstock, an alloy sleeve swaged over the it will eventually fail. Typi- cable turnback. The durable, cally manufactured in two strong sleeve requires the use of pieces from manganese a special swaging tool, and once bronze or aluminum, quad- crimped, the sleeves are not rants must be machined reusable. Only stainless-steel or to provide just the right copper sleeves (the latter may be amount of clamping action tin-plated, which appears silver when installed. (The bore, or and is often mistaken for stain- hole, in the quadrant is usu- less steel), not aluminum, should be are stainless-steel threaded rod (forged ally about 0.005"–0.006"/0.127mm– used for stainless-steel-wire rope. rather than cast) whose end is formed 0.152mm smaller than the outside Normally, steering system termina- into a closed loop, or eye. They enable diameter of the rudderstock.) If the tions, whether they use compression tension to be transferred from the wire clamping action is insufficient, the fittings or clamps, are made in only rope to the quadrant, as well as afford- quadrant could shift, leading to gall- two locations: to the chain at the helm ing some adjustment to the wire’s ten- ing, and/or slide down the stock, using a stainless-steel self-locking sion. They are typically secured to the causing cable misalignment and shackle or chain adapter, and at the quadrant with three nuts—two on one steering failure. If the clamping action quadrant’s take-up eye. Take-up eyes side of the quadrant pass-through and is too great, the quadrant could bend,

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August/September 2018 25 SYSTEMS: Steering, Part 1

Left—The bore in this radial drive casting was likely undersized for the stock, so it cracked when the clamping fasteners were tensioned. Right—If the design can support them, radial drives offer the potential benefit of eliminating a set of sheaves. and crack when the affixing bolts are stock the most common and secure. Other methods include install- tightened. preferred method uses a key that ing dual set-screws tapped into the In addition to the clamping action, interfaces with keyways cut into the quadrant cap as well as the rudder- the quadrant and stock must be stock and quadrant. When properly fit stock or using a stainless-steel securely locked together. On solid- and installed, this method is reliably through-pin (not an ordinary bolt)

26 Professional BoatBuilder that passes completely through the that, where geometry permits, two of drives. Naval architects, boatbuilders, quadrant and the stock. The latter two the idler sheaves may be eliminated and service yards must do their methods are often used on hollow- from the installation, simplifying the respective homework when sizing a stock rudders. system and reducing weight while tiller arm, be it for primary hydraulic For absolute security with either minimizing friction and wheel effort. steering or autopilot use (autopilots method, if all fasteners aren’t nylon Radial drives are well suited to vessels self-locking, use a thread-locking where cables can be led directly from compound. As previously mentioned, the wheel pedestal to the rudder and metallic components must also be gal- where rudderstocks are vertical rather vanically compatible: never use bronze than raked fore or aft. quadrants on aluminum rudderstocks or vessels, or brass keys in aluminum Tiller Arms rudder or quadrant keyways. Although these are most often Radial drives, a variation on quad- associated with hydraulic steering rants, utilize a 360° wheel, as opposed (which I’ll discuss in “Steering, Part to the quadrant’s partial arc. Often 2,” in Professional BoatBuilder No. used on performance-oriented , 175), tiller arms are used in conjunc- radial drives are typically manufac- tion with nearly every type of system tured from anodized aluminum. Much to facilitate a connection between the like quadrants, they are built in two rudderstock and a linear autopilot Ideally, tiller arms should fit snugly pieces and then clamped to the stock ram. Whatever the reason for using a against the rudderstock. The gap by the same methods of engagement: tiller arm, it’s important that sizing, between the two halves of this clamp keys, pins, or through-bolts. The fit, and attachment receive the same arrangement places extra tension on its advantage to using a radial drive is attention as quadrants and radial fasteners.

August/September 2018 27 SYSTEMS: Steering, Part 1

The tight fit between Additionally, the geometry between the halves of the cast the tiller arm and the ram must be cor- tiller and the rudder- rect to derive the greatest mechanical stock minimizes advantage when it’s needed most— torquing loads and when the rudder is moved away from makes a strong, amidships; while it’s dead ahead, the reliable installation. least effort is required. Ideally, and contrary to popular belief, the ram should not be positioned at 90° to the tiller arm and vessel centerline (assum- are often installed as ing, in this example, that the tiller is an aftermarket item, fore-and-aft when the rudder is fore- so boatyards and and-aft) when the rudder is straight electronics installers ahead; rather, it should be at 90° when must get this por- the rudder is over to some degree tion of the equation (steering and autopilot manufacturers right) to ensure proper operation. If an arc approximately 35° from amid- typically specify the degree) in either the arm is too short, the ram may be in each direction), and the direction, thereby enabling the ram to overworked or not powerful enough rudder may impart too much force impart greater force when it’s needed to move the rudder. If the tiller arm is on the steering system or autopilot. most. This often means the ram, if too long, insufficient travel may pre- Many manufacturers provide tiller installed athwartships, must be posi- vent the rudder from being put hard arms with the choice of several con- tioned farther aft. over (though it varies with vessel nection points to the ram, offering The loads placed on tiller arms are type, rudders typically swing through some versatility. considerable, no less than on quadrants

28 Professional BoatBuilder Counterintuitively, the angle between a steering ram and a tiller arm, when the rudder is dead ahead, should not be 90°. Shown here is a proper ram-to- tiller arm angle.

and often greater, because they are manufacturers. Much like the quad- not too tight and not too loose, and my used for hydraulically assisted or fully rant, the clamp fit must be just right, preference is for a keyed interface powered steering and autopilots. Off- whenever and wherever possible. Ram the-shelf tiller arms, as well as selec- installation details are discussed fur- For more on rudders, go to tion guidelines and assistance, are ProBoat.com. ther on the next page, in the Autopilot available from steering component Installation Guidelines sidebar.

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Cable over Sheave with a Twist this is important because it often alerts steering, and pull-pull steering systems Among cable-over-sheave systems’ the crew to the need for sail changes come into play. These utilize cables and many attributes is their rugged, reliable or trim adjustment. While hydraulic sheaves married to a flexible conduit construction. To those at the helm, they systems have their own advantages— that roughly resembles an outboard also offer feedback, or feel for the especially their ability to send helm jacketed-cable steering system. The rudder load. Aboard a sailing vessel commands from the wheel to the rud- steering cable slides within this plastic- der through long, often circuitous coated metallic jacket, or conduit, aided lengths of twisting, turning hydraulic by ample grease. hose without suffering any degrada- The greatest advantage of a pull-pull tion in steering effectiveness—they system is that the run between the offer no feedback. Because the helms­ steering wheel or pedestal and the rud- person cannot determine how much der need not be a series of straight lines, load is being placed on the rudder, seri- as is the case with traditional cable- ous sailors often shun hydraulic over-sheave systems. The cable-and- jacket combination can make turns and bends, albeit gentle ones. Thus, center- A pull-pull system relies on a jacketed sailboats, for instance, with cable similar in concept to that used for notoriously difficult cable runs, don’t outboard steering and shift-and-throttle have to resort to hydraulic steering, and control. It allows for routing in ways a feedback is maintained. conventional cable-over-sheave system could not support. However, the jacketed Pull-pull steering’s limitations cable is intolerant of high loads and include, as one of the primary manu- sharp bends; a proprietary sheave facturers of these systems warns, not system can accommodate the latter. making any 90° bends in the cable on

Autopilot Installation Guidelines

lthough it was more than two selection, sometimes more so. An A decades ago, I remember the pas- expensive full-function system poorly sage well. On a shorthanded delivery installed is worthless compared to an from Bermuda to New England, I was economy system correctly installed. helping the skipper back to his home Many builders tap the power of redun- port and looking forward to a leisurely dancy by installing twin autopilots on passage. Within a day of leaving St. many oceangoing vessels, power and David’s Light in our wake, the boat sail. inexplicably rounded up. After disen- First, lay out the system mentally gaging the autopilot, my shipmate took before committing it to paper. Visual- the wheel while I investigated with a ize where each component will fit, flashlight. The autopilot drive motor— where cables will be run, and what a chain-and-sprocket affair located in storage space will be lost. Take into Proper autopilot installation on a quad- the binnacle under the wheel—had account serviceability and access for rant or radial steering system should wrenched free from its plywood base, repairs. How difficult will it be to reach include an independent tiller arm like this breaking one of its nylon gears. Along each component, especially the drive one clamped to the rudderstock above with squalls and heavy lightning mechanism? Will the drive or tiller the steering quadrant. Note the poorly storms, the voyage was plagued by arm (the device that connects the drive routed, chafe-prone control cable running over the tiller arm—a common scenario other gear failures, and the autopilot ram to the rudder) interfere with gear in binnacle-equipped vessels. drive could not be repaired with the stored in this space? If so, a partition vessel’s onboard spares. must be installed. If the autopilot uses Autopilots are inextricably linked a separate rudder-angle transducer, more delicate than the linear variety). with a vessel’s steering system, and then this must be protected as well A single pull from a dockline, life proper installation is as critical as (rotary rudder-angle transducers are jacket, or drawstring snagged on this

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Right—Tiller arm length is determined by a pragmatic compromise between needed leverage and available throw. Far right—Do not underestimate the loads imparted by autopilots to shelves and support structures. These designs must be robust and capable of with- standing thousands of cyclical loads.

important device could cause hun- of the rudder or outboard. It’s almost dreds of dollars of damage, as well as impossible to control either one, espe- an autopilot malfunction. cially in a beam or following sea. This The linear drive unit is the autopilot is a crude but telling approximation of component I’ve seen most often incor- the loads a linear drive is subjected to rectly installed. To understand the with the average-length tiller arm for loads imparted to this area, do the fol- hundreds or thousands of hours. A lowing test: On a tiller-steered boat or chain-and-sprocket or geared system even on a small outboard-powered may face even greater torque. Accord- dinghy, steer as you normally would, ingly, these drive units must be very secure the drive mechanism to a holding the tiller near its forward end. solidly secured to the . Only stringer, bulkhead, or well-glassed-in Now, choke up to within a few inches through-bolts should be used to shelf, and backing plates are a must.

32 Professional BoatBuilder Pull-pull system are, as one might suspect, related to internal steel installation and maintenance as well as cables ride inside to overloading. Common shortcom- a flexible steel jacket. Adequate ings involve making too sharp or too lubrication to pre- many turns with the conduit and fail- vent drag and cor- ing to use idlers at sharp turns or to rosion is essential. properly terminate the cable end, Grease cups, like which causes it to peel back, splay the one shown open banana peel–style, or be crushed here, aid in that like an empty soda can. Failure to effort. lubricate the cable will, of course, accelerate wear and make steering labor-intensive. The primary shortcoming of pull- vessels more than 30' (9.1m). Changes any conduit run of more than 6' (1.8 pull systems, when compared to tradi- in cable elevation and direction should m) to be installed using a purpose- tional cable-over-sheave steering, is be kept as slight and gentle as possible; made greaser (a grease cup rotated to they can’t be easily inspected (the cable idlers (sheaves) should be used when force grease into the conduit). The itself can be seen only at the ends), or a sharp(er) turn must be made. Criti- preferred lubricant for these systems repaired at sea without proprietary cal in nearly all steering systems, lubri- must be low viscosity and typically components. If this system should fail, cation is especially important in pull- Teflon-based, so grease cups can force repair parts must likely be obtained pull systems. When in daily use, the it into the conduit. from the manufacturer. As with any entire system must be lubricated In my experience, the primary steering system, vessel operators should monthly. The manufacturer calls for modes of failure for pull-pull systems carry a supply of relevant and correct

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Do not use tapping screws or lag possible and as large as practical. prohibit piggybacking a linear auto- bolts. If you must do so, as shown For hydraulic or electric linear pilot drive onto the quadrant, and in the right-hand photograph on rams, the dedicated autopilot tiller this makes good sense. Although it’s page 32, they should be in as many arm may be attached to the rudder- more time-consuming and costly to different axes as possible—some in stock at any location around the install, an independent tiller arm shear, i.e., perpendicular to the shaft, as long as it fully engages the affords greater redundancy. In the direction of effort. Use as many as key. Some quadrant manufacturers most popular types of mechanical steering for cruising sailboats— cable-over-sheave, pull-pull, or geared drag-link systems—if the cable breaks, or the quadrant slips, or some other component gives up, the boat can often still be steered with the autopilot if a separate tiller arm is used. As mentioned in the main text, bronze and aluminum components are galvanically incompatible. Rud- derstocks may be bronze, stainless steel, or in some cases aluminum (particularly on an aluminum ves- sel). Quadrants, as well as tiller arms, may be aluminum or bronze. Ensure that metals unfriendly to each other, particularly aluminum and bronze, are installed so they won’t come in direct contact. Water dripping from a bronze tiller arm onto an aluminum quadrant or hull could cause severe galvanic corro- sion over the years. A final word on installation: It is critical that linear drive units have more travel than the tiller arm. They should never function as rudder stops, or shorten the travel of the rudder. Aboard a sailing vessel with only one autopilot control/display, it is probably best to install it near the helm, so it can be adjusted, moni- tored, and disengaged easily. If installing multiple stations, or a handheld remote, the main unit should be at the navigation station, and the remote at the helm. Most remotes utilize a multipronged plug, but with the trend toward wireless accessories, other newer models are not limited by this electronic tether. Because the drive unit’s electrical consumption can be prodigious, especially in a seaway, a voltage drop

34 Professional BoatBuilder Outboard-powered vessels often utilize what’s known as a push- pull system, which employs a jack- eted, internally lubricated cable. The cable’s pri- mary weakness is seizure after long disuse, so it’s difficult to lubricate it too much.

spare parts, as well as an emergency jacketed cable translates rotary motion reduction-gear (the latter use smaller tiller. from the wheel to linear motion at the gearboxes) versions, as well as those Push-pull systems (a variation on engine or -drive. Helms should be that eliminate feedback, making for the pull-pull technology) have been matched to the load; larger, heavier safer operation as the wheel does not broadly applied to steer outboard and engines and boats call for lower gears, rotate quickly should a driver lose his stern-drive vessels for more than half a resulting in more turns lock to lock, or her grip. century. Available in rotary or rack- with lower effort. Systems are available The most common failure modes and-pinion designs, a single rigid-core, in conventional planetary as well as for push-pull systems involve seized

August/September 2018 35 SYSTEMS: Steering, Part 1

of no more than 3% must be achieved. wiring’s overcurrent protection I routinely see valves and cast-bronze The calculation for this formula must should be a circuit breaker rather plumbing fittings rated for 400 psi or include a “there and back” figure for than a fuse. If a failure occurs, it may 600 psi (27.6 bar or 41.4 bar) in these the electrical-supply cable. If, for take several blown fuses to identify systems, with many of the valves leak- instance, the drive unit is 20' (6.1m) the problem. Then they must be ing from seals. Make certain from the main power-distribution replaced, whereas a circuit breaker that the autopilot’s motor and sole- panel, the voltage-drop formula can simply be reset. noids are rated for the vessel’s voltage. would utilize 40' (12.2m) of cable for To help ensure the reliability of a In some cases, mismatched pumps the overall run. This information can hydraulic autopilot, i.e., a hydraulic and components will work for some be found in the ABYC Standards and pump that acts on the vessel’s existing time before failing. elsewhere. In addition to perfor- hydraulic steering, rams, etc., follow Electrical connections should mance and efficiency, a low-voltage these details: Size the pumps to meet include service and drip loops in each scenario can noticeably shorten the the demands of the vessel’s displace- wiring run. Heat-shrink connectors life of an electric motor, and under- ment, rudder size, and speed. Plumb offer the greatest degree of strain sized cabling will surely exacerbate the pumps with isolation valves that relief and water resistance. Over­ this. Connect the drive unit and limit damage in the event of a leak. current protection for the entire auto- power supply via an insulated marine- All valves, plumbing, hose, etc. must pilot system should be a circuit rated terminal block to accommodate be rated for the system’s relief pres- breaker as opposed to a fuse. The cir- the difference in wire size between the sure, which, even for manual systems, cuit breaker should be easily accessi- drive unit and vessel side of the cable is typically 1,000 psi (69 bar). The ble, well labeled for resetting, and run as well as to ease service and above-mentioned wire size and cir- dedicated to the autopilot alone. replacement. Ideally, the auto­pilot cuit breaker issues apply here as well. Most installation manuals are fairly

36 Professional BoatBuilder Installing the functional. Lubrication with high- helm radial gear- viscosity water-resistant grease and box of a push- regular inspections for wear and loose pull system on a fasteners are key maintenance items. small runabout presents its own Push-pull systems are available in challenges in single- or dual-station designs. Those meeting cable working on and repairing these sys- manufacturers’ tems must always demand original bend-radii limits equipment manufacturer parts for to ensure smooth new installations and repairs; field- operation. substitutes are unacceptable. Geared, and Rack-and-Pinion The final mechanical system we’ll discuss utilizes neither pulleys nor conduits but instead the tried-and- true interface of metal teeth, threads, cables (the ends are stainless steel, embossed with a part number and and gears. In one form or another, however the core and jacket cables length. While a seized cable can geared steering systems have been are mild steel, so if the outer plastic sometimes be freed up, and a tilt tube around for well over a hundred years. jacket is pierced, water will enter, cleaned with a bronze rotary brush Worm gears offered strong, reliable causing rust and seizure); cables and lubed, repairs are typically steering to many craft both power seized inside outboard tilt tubes; and impractical. Cables and helms are and sail; they are considerably less stripped helm gears. Most cables are simply replaced when no longer common now, available from only a

August/September 2018 37 SYSTEMS: Steering, Part 1

Left—Many vintage steering systems like this worm gear rely on mild steel parts, making inspection, lubrication, and corrosion inhibition critical. Right—Similarly, reliable rack-and-pinion systems, which expose the lubri- cating grease to open air and contamination, should be periodically cleaned and the grease replaced. few manufacturers. Their primary years. Referred to as rack-and-pinion, than gear-to-rack), offered by several advantages are strength and simplicity, or drag-link, steering, this system manufacturers, are strong and rugged but the design limits feedback to the offers the advantages of using neither and provide feedback to the helmsper- helmsman, so they are not recom- cables, sheaves, nor conduits and has son. Used primarily on sailboats, a cir- mended for balanced rudders and fin more in common with the system in cular geared rack in the helm pedestal boats, where a sensitive helm is a an automobile than with those aboard is turned by a pinion attached to the virtue. boats. Rack-and-pinion systems (with wheel shaft. As the rack rotates, it Another variety of geared steering a variation being gearbox steering, turns a vertical torque tube connected system has become popular in recent with a gear-to-gear interface rather to a tiller arm at its base. This tiller arm

The majority of hydraulic autopilots and manual hydraulic steering systems operate with a relief pressure of 1,000 psi (69 bar). All plumbing components—rams, hoses, and fittings—in these systems must carry this minimum pressure rating.

specific about where and how to from large iron masses, such as the temporarily until sea trials are com- mount the fluxgate compass. Of engine and /rode, or electric plete to ensure that it’s well placed course, the farther this component is motors, pumps, and high-current and not affected by any of the afore- cabling, the better. Post placards in mentioned objects. lockers and storage spaces adjacent to Swinging or calibrating the com- the fluxgate compass prohibiting the pass is a critical part of the installa- storage of ferrous metal objects (one tion. Follow the manufacturer’s can of beans can ruin an autopilot instructions meticulously. When cali- and your day). Install the fluxgate brating, it is best to energize all loads that will normally be on while you are under way, day and night. Electric Ideally, autopilot fluxgate compasses current sets up a magnetic field that should be installed no closer than 1m will sometimes affect the perfor- (3.3') to ferrous metals, including tools, mance and accuracy of any compass. motors, and even some tinned foods. —Steve D’Antonio

38 Professional BoatBuilder SYSTEMS: Steering, Part 1

More akin to the systems in automobiles, drag-link steering does not use cables, jackets, or hoses. Instead, gears, lever arms, and tie rods allow the system to convert rotary to linear motion and transmit move- ment to the rudder.

is attached, via an adjustable drag link increases with the rudder angle, while wheel. It’s critical that these systems be or tie-rod, to a similar tiller arm located maximum sensitivity is maintained set up properly to ensure that the on the rudder shaft. Referred to as when the rudder is amidships. steering operates with the least effort. wide-angle geometry, there’s a value- This means that as the rudder is I’ve seen several production vessels added benefit to this type of system: turned farther, which increases the whose drag-link-steering systems by making the tiller arm that’s attached resistance placed on it, the angle were installed incorrectly at the fac- to the base of the torque tube shorter between the drag link and the center- tory, making for erratic or overly than the tiller arm attached to the line increases, which in turn dimin- strenuous steering. Installing any rudderstock, the mechanical advantage ishes the effort required to turn the steering system per the manufacturer’s

August/September 2018 39 SYSTEMS: Steering, Part 1 guidelines is well worth the effort. be installed between the wheel and the components, drag-link steering nearly Because corrosion can be an issue on rudder. If the wheel is too far from always requires special parts for key components made from mild the rudder (with bulkheads or other repairs. steel, they should be carefully interior structures between them) or if The good news is that the simplicity inspected, particularly in existing sys- the elevation between the rudderstock of this robust system makes failures tems, and may require supplemental and the base of the cockpit is signifi- uncommon. Regular inspections and corrosion inhibition. cantly different, it may not be possible lubrication of all moving parts and To utilize this system, the vessel to use this type of steering. And, much bearings, as well as periodic mainte- must be designed so the drag link can like other systems that use proprietary nance, will help ensure trouble-free performance. Hydraulic steering systems for power and sail will be discussed in “Steering, Part 2,” in the next issue, PBB No. 175.

About the Author: For many years a full-service yard manager, Steve now works with boat builders and owners and others in the industry as Steve D’Antonio Marine Consulting. He is an ABYC-certified Master Technician and sits on that organization’s Hull and Piping and Engine and Transmission Project Technical committees. He’s the technical editor of Professional BoatBuilder.

Information & Resources

Relevant ABYC Chapters P-17 Mechanical Steering Systems P-18 Cable over Pulley Steering Systems Edson (www.edsonmarine.com) Hynautic/SeaStar (www.seastarsolutions.com/ products/hydraulic-new/inboard- new/hynautic-new/) Jastram (www.jastram.com) Jefa (www.jefa.com) Kobelt and Accu-Steer (kobelt.com) Raymarine (www.raymarine.com) SeaStar Solutions – Teleflex (www.seastarsolutions.com) Wagner (www.wagnerengineer ing.ca/) Uflex (uflexusa.ultraflexgroup.com)

40 Professional BoatBuilder SYSTEMS: Steering, Part 1

August/September 2018 41