GAS­KET CASE

Cruising World - - Hands-On Sailor - BY STEVE D’AN­TO­NIO

When it comes to long-dis­tance cruis­ing, ev­ery sailor needs more than ruise for long enough and you’ll be faced with a sit­u­a­tion where you’ll need to make a gas­ket for your propul­sion en­gine, ten­der out­board, genset or other on­board gear. While it’s al­ways best, and eas­i­est, to use the man­u­fac­turer’s orig­i­nal equip­ment gas­kets, these may no longer be avail­able, or inac­ces­si­ble if you are at sea or cruis­ing in a re­mote lo­ca­tion.

Sev­eral years ago, while cruis­ing along New­found­land, Canada’s south coast — where

Ca pass­ing fa­mil­iar­ity with gas­kets and sealants.

MONTHLY MAIN­TE­NANCE

there are few ports and fewer chan­d­leries or auto-parts stores — I was faced with a leak­ing heat ex­changer end-plate gas­ket. An im­peller fail­ure had forced the re­moval of the cover plate for clean­ing, and in the process, the gas­ket was dam­aged. No amount of “form-a-gas­ket” (more on this in a mo­ment) would hold up in the dam­aged area for more than a day of run­ning. Ul­ti­mately, af­ter turn­ing the boat up­side down for suit­able ma­te­rial from which to make a gas­ket, I used the cover of the HO 249, the sight-re­duc­tion ta­ble. It was nearly the same thick­ness as the orig­i­nal gas­ket, and once slathered with sealant and com­pressed, it re­mained liq­uid-tight for the re­main­der of the pas­sage. It wasn’t a per­fect so­lu­tion, but it worked un­til a proper gas­ket could be sourced.

Ide­ally, how­ever, you’ll want to carry the most com­mon gas­kets (and/or O-rings), such as those used for the heat ex­changer; and rawwa­ter-pump cover plates; fuel pumps; raw-wa­ter-pump flanges (if gear-driven); and valve cov­ers to name a few. De­pend­ing on your skill level, and how far you’ll ven­ture from parts re­sources, you might also wish to carry oil pan, ex­haust, in­take man­i­fold and head gas­kets.

Paste or form-a-gas­ket com­pounds are also a valu­able re­source be­cause they can be used either to make a gas­ket you oth­er­wise don’t have or to re­place orig­i­nal equip­ment self-form­ing gas­kets that are dam­aged, as they al­most al­ways are dur­ing dis­as­sem­bly. Many mod­ern en­gines forgo con­ven­tional gas­kets al­to­gether, re­ly­ing en­tirely on self-form­ing gas­kets. Those used in en­gine ap­pli­ca­tions are typ­i­cally known as RTV-S, or “room tem­per­a­ture vul­can­iz­ing sil­i­cone,” a ver­sa­tile ma­te­rial that’s avail­able in a wide range of op­tions, from ul­tra-fast-set­ting (these can be used lit­er­ally one minute af­ter assem­bly) to high tem­per­a­ture (up to 700 de­grees Fahren­heit) to ap­pli­ca­tions such as ex­haust man­i­folds and tur­bocharg­ers. Paste RTV-S is of­ten used to aug­ment con­ven­tional fiber gas­kets, im­prov­ing leak re­sis­tance; how­ever, this ap­proach may be prob­lem­atic be­cause there is a dif­fer­ence be­tween a form-a-gas­ket com­pound, one that’s de­signed to act as the sole gas­ket, and a “gas­ket dress­ing,” a com­pound de­signed to aug­ment the prop­er­ties, ex­tend the life or im­prove leak re­sis­tance of con­ven­tional gas­kets. Fur­ther­more, some gas­kets (for in­stance, those used for cylin­der heads) are de­signed to be in­stalled dry. In cases where I’m con­cerned about leak­ing on an older in­stal­la­tion, I have used aerosol spray-on cop­per-based gas­ket ma­te­rial, which is de­signed for ap­pli­ca­tions of this sort.

Next month I’ll cover mak­ing your own gas­kets and proper gas­ket-in­stal­la­tion tech­nique.

Steve D’an­to­nio of­fers ser­vices for boat own­ers and buy­ers through Steve D’an­to­nio Marine Con­sult­ing (steved­marinecon­sult­ing.com).

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