Shifty Busi­ness

A fail­ure of shift and throt­tle ca­bles can ruin your day. Here’s how to en­sure that all your dock­side land­ings are happy ones.

Cruising World - - Contents - Monthly Main­te­nance By Steve D’an­to­nio

Keep link­age ca­bles well lubed for smooth sailing.

Shift and throt­tle mech­a­nisms — the ca­bles, lever arms, cle­vis pins and so forth — are for the most part sim­ple and rel­a­tively re­li­able. How­ever, it takes no more than a sin­gle loose fas­tener, or im­prop­erly in­stalled cot­ter pin, to wreak havoc on a ves­sel’s op­er­a­tion.

Sev­eral years ago, while work­ing as a me­chanic at a ma­rina, I watched a boat owner land his 40-foot sloop on a dock in text­book fash­ion, com­ing along­side, shift­ing into re­verse smartly and bring­ing the ves­sel to a halt. The owner then jumped onto the dock with spring line in hand, but as he pre­pared to make it fast to a cleat, it was pulled from his hand. The ves­sel, it turned out, was still in re­verse, and be­cause the rud­der was still slightly over, it de­scribed a large cir­cu­lar path, where­upon it made con­tact with the dock once again and was brought un­der con­trol. A sim­i­lar event oc­curred in 2005, with far greater con­se­quences, when a ferry in British Columbia crushed 22 boats berthed in a ma­rina ad­ja­cent to the ferry slip as it lost con­trol while land­ing. The cul­prit in both cases? A sin­gle failed cot­ter pin.

The vast ma­jor­ity of shift and throt­tle con­trols rely on the fa­mil­iar plas­tic-coated wire jacket with a mov­able wire core. In or­der for this sys­tem to work prop­erly, sev­eral cri­te­ria must be met. First, the jacket must be com­pletely im­mo­bi­lized at both ends. This is typ­i­cally ac­com­plished with a U-shaped clamp mech­a­nism, or a scis­sors-style hook clip; this is through-bolted to a sturdy bracket at the en­gine end, and to the con­trol it­self, or the bin­na­cle or cock­pit, at the other end. With the jacket sta­tion­ary, move­ment of the shift lever causes the cable core to move smoothly. If, how­ever, the jacket is not se­cure, it will move with the core, pre­vent­ing the lat­ter from tele­graph­ing move­ment to the en­gine. The U- and hook clamps should be rou­tinely in­spected for move­ment and cor­ro­sion.

The core must be se­curely at­tached to the shift/throt­tle lev­ers at the helm, as well as at the en­gine/trans­mis­sion. This is nearly al­ways ac­com­plished us­ing pro­pri­etary threaded cable adapters, which are avail­able in a wide range of de­signs. The pro­pri­etary as­pect is im­por­tant. “Field-en­gi­neered” adapters, com­mon nuts, or or­di­nary bolts and screws must never be used in this ap­pli­ca­tion. Only com­po­nents supplied by the cable man­u­fac­turer should be re­lied upon to adapt cable ends to throt­tle con­trols, the trans­mis­sion shift and in­jec­tion-pump throt­tle lev­ers.

Wear is an ever-present is­sue where con­trol ca­bles and their ter­mi­nals are con­cerned, par­tic­u­larly where soft met­als such as brass meet hard met­als such as steel. Lightly lu­bri­cat­ing this in­ter­face will ex­tend the life of these parts, while uti­liz­ing ar­tic­u­lat­ing ball ends can vir­tu­ally elim­i­nate wear al­to­gether. In most cases, cable end ter­mi­nals are plated mild steel, which means they will even­tu­ally rust if not cor­ro­sion-in­hib­ited. Cable jack­ets, which are plas­tic, are also sub­ject to chafe and melt­ing if they come into con­tact with hot sur­faces, such as ex­haust man­i­folds. Once the jacket is pierced, mois­ture can en­ter, which will cause rust and cable seizure.

Where cot­ter pins are used to se­cure cle­vis pins or cle­vis-style ter­mi­nals, a washer should be in­stalled be­tween the cot­ter pin and lever sur­face, and again, lu­bri­ca­tion should be added. Cot­ter pins and wash­ers should al­ways be stain­less steel.

Eye pins, an al­ter­na­tive to the cot­ter-pin ar­range­ment, uti­lize gos­samer and eas­ily lost C-clips. If your sys­tem re­lies on these it’s best to keep a spare or two aboard. All fas­ten­ers used in con­trol cable sys­tems should be self-lock­ing or uti­lize lock wash­ers, and the ad­di­tional use of thread-lock­ing com­pound rep­re­sents a belt-and­sus­penders ap­proach.

All read­ily ac­ces­si­ble com­po­nents in this sys­tem should be in­spected at least monthly, while less ac­ces­si­ble parts (for in­stance, those inside the bin­na­cle) should be care­fully re­viewed at least an­nu­ally, look­ing for rust, wear and unwanted move­ment.

When brass cable ter­mi­nals are used with steel throt­tle or trans­mis­sion lever arms, the for­mer will wear (left). Such in­ter­faces should be lu­bri­cated, and wash­ers used with cot­ter pins. Mild steel is prone to cor­ro­sion, and shift and throt­tle com­po­nents are no ex­cep­tion (mid­dle). They re­quire rou­tine in­spec­tion and lu­bri­ca­tion. Cir­clip-style re­tain­ing rings (right) are small, spring-loaded and eas­ily lost. Carry spares. They are mild steel and should be cor­ro­sion in­hib­ited.

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