Spare Those Parts

It's February, the days are getting longer and you've already started to plan your spring and summer cruising schedule. Now is the time to be thinking about taking inventory of your onboard tool kit and spare parts.

It’s February, the days are getting longer and you’ve already started to plan your spring and summer cruising schedule. You know where you’re going. You have a list of things to do on the boat and things to buy. Now is the time to be thinking about taking inventory of your onboard tool kit and spare parts.

Yes, you may have done this last year. But that’s no reason not to take another look at what you have. Many parts can go bad on you and, when a mechanic pokes through the boxes, he may just shake his head and order all new parts, leaving you to wonder where you went wrong.

Take the spark plugs on a gas engine, for example, which are items that most boat owners consider an essential spare. First, the plug itself is steel, and we all know what happens to mild steel in a damp atmosphere. The most important part of the plug is the firing tip, and it doesn’t take much time for rust to build up and clog the tip so that it will be even less usable than the plug you need to replace.


Second, you’ve probably contributed to this problem by leaving the plug in the original cardboard box, which absorbs and holds moisture to create a rich environment for rust. Spark plugs, which should be pre-gapped for immediate use, can rust solid if not properly protected. Your spare distributor points can pit on the faces without ever being used; even the brass found in many electrical parts can corrode to uselessness in a damp marine environment.

The same thing holds true for the spare parts on a diesel engine as well. You took your engine serial number to the dealer’s parts department and made sure that you bought the right fuel injector, and then you tucked it away in a locker, still in the original cardboard box. Given the right conditions, that injector can be totally useless in six months.

The problem isn’t confined to metal parts, either. You probably carry a set of spare gaskets, which you’ve cleverly stored under a bunk cushion to keep them flat. Since many gaskets are paper-based, the trapped moisture under a cushion can cause them to delaminate in short order, and they may literally fall apart in your hands just when you need them.


Rubber and neoprene belts and hoses are also prone to fail because of improper storage procedures. If you tuck a preformed cooling hose into a box in the engineroom and allow it to bake every time you run your engine, it will soon deform to the shape of its storage position and you may not be able to install it when you need it. The fins on spare flexible water-pump impellers can warp if they aren’t stored flat, and even V-belts, if left in a twisted position, may jump off the pulleys in spite of how tightly they are tensioned.

How should you store your spares so they are still good when you need them? The first and most important factor is to keep them insulated from the moisture-laden air. Several experienced charter skippers spray their spark plugs or fuel injectors with WD-40 or CRC 6-66 and then seal them in Ziploc bags for long-term storage. One tugboat skipper I know dips each spare injector in Marvel Mystery Oil and then uses his wife’s food sealer to package the dripping part in an airtight plastic package.

Electrical parts should also be sprayed lightly with rust-preventive lubricant and then sealed up. Large spare parts such as water pump assemblies or solenoids will fit in moisture-proof freezer containers, and gaskets can still be kept flat under bunks if they are properly moisture-proofed. Small gaskets can be put in envelopes, labeled and then filed in three-ring binders that also hold engine manuals or catalogs.


The entire package of spares should be stored in an area that is dry and free of heat extremes. The engineroom is a good place to store spares as long as they don’t get overheated, and fragile parts can be protected in bubble wrap.

You may prefer to assemble your own spare-parts kit, or you can rely on the pre-packaged kits available from many manufacturers. The number and quantity of spares you carry is directly dependent upon how far you cruise from a source for parts-the farther away, the more spares you need. Another consideration for spares is the number of hours on your engines, since a major overhaul on an older engine obviously needs more spares. Whether you choose a pre-packaged spare-parts kit or assemble your own, one important caveat is to make sure you have any specialized tools for the installation or adjustment of those parts. Some distributor hold-down bolts may be inaccessible without a U-shaped wrench, and some fuel injectors take special tools to tighten them into the confined head. Mentally walk through every installation and adjustment process to make sure you have the tools you need.

When buying spare parts, be sure to copy the exact engine model and serial number, plus any other stamped information, from the plate on each engine. If possible, compare the spare with the original part to make sure you have an exact duplicate. One of the most important items to have in conjunction with your spare parts is a comprehensive shop manual for each engine. Even if you aren’t capable of major repairs, any shade-tree mechanic can handle the task if he has the parts and a manual.


Many engine manufacturers offer spares kits through their local dealers, with the parts prepackaged in airtight boxes for long-term storage. Caterpillar, for example, offers three kits for its 3208 diesels. The Cruise I kit, for inland and shoreline use, contains filters, gaskets, a seawater pump kit and various hoses and belts. The Cruise II package, for offshore cruising, adds injectors, while the Cruise III box is filled with items needed for distant voyages.

Volvo Penta supplies spare parts in rustproof cases that float, and Twin-Disc even has a kit for transmission repairs. Westerbeke, in addition to prepared spares kits for generators, supplies its dealers with How to Select Your Westerbeke Spares brochures.

With your cruising plans in mind, choose your spare parts carefully and then store them so that they’ll be immediately ready for use. A spare part that is allowed to go bad provides a false sense of security, and that’s worse than no spare at all.

The Checklist
Gas-engine Spares · Spark plugs, one set, pre-gapped · V-belts, one spare for each V-belt on the engine · Water pump impeller · Fuel filter or filter element · Fuel pump rebuild kit · Cooling water hose, equal to longest hose, plus hose clamps · Engine oil · Transmission fluid · Ignition points · Condenser · Distributor cap · Distributor rotor · Ignition coil · Ignition ballast resistor · Spark plug harness · Head gaskets · Gasket material, one sheet · Power steering fluid Diesel Spares (in addition to above) · Fuel injector · Fuel pump diaphragmMiscellaneous · Fuses, one complete set · Light bulbs, one complete set · Propeller · Shop manual · Ignition key, one extra · Windshield wipers · Head rebuild kit