Barring the demise of a heretofore unknown wealthy uncle who leaves you enough dinero to spring for a pair of Merc HP1075 SCi's for your boat, chances are you claim to be happy with the engine or engines your boat has in it at present. After all, your boat came with what it came with and does what it did when you purchased it. OK, maybe it doesn't seem to be quite as quick as it used to be, but still ...

The Coast Guard as well as other marine associations have conducted studies that show the average boater gets out on the water from 40 to 110 hours per year. Only 12 percent of boaters use their craft in excess of 300 hours per year, according to a 2000 U.S. Bureau of Transportation Statistics survey.

Why is this important? Because according to one study, the average cared-for gasoline engine in marine usage will need a major overhaul at about 1,500 hours. But think about other factors that affect your marine engine's longevity. It sits for long periods of time, doesn't get used much, and when it does, it gets used hard, in a harsh environment ... the negative factors just keep adding up.

So, what do you do to keep expensive repairs away and performance the way it was when you purchased your boat? That's right, you pay attention to it.

Engine Blood.
Since you're not talking about mounting turbochargers or bigger carburetors, you're limited to keeping your engine tuned and fed properly.

Warranty issues aside, for most boat owners a yearly change of oil and filter will suffice. One thing that's a must: Check your oil before every trip's startup, and check the dipstick with your fingers. If you feel anything solid or gritty on the stick, you've got something wrong. Ditto if the oil comes out milky; that means there's water in the oil.

A word about additives: Some people swear by them, while others don't. Additives add various substances to motor oil with the stated object of enhancing your boat's performance. Dupont's Teflon, also called PTFE (polytetrafluoroethylene) is a big favorite.

In fact, any oil that's designed for your boat's engine has additives in it already. The additive in 2-stroke oil adheres to a National Marine Manufacturers Association (NMMA) minimum called TC-W3 (two-cycle, water-cooled) and is an additive that addresses emissions, carbon buildup and ring wear among other things. FC-W (four-cycle, water-cooled) is the four-cycle rating and addresses the same problems. For more information, check the NMMA oil certification information at www.nmma.org.

Gas additives, on the other hand, may not be such a bad idea. Carbon deposit buildup is the engine bugaboo, so an additive that addresses that is smart. For example, you're facing an idling problem with your 3.0L MerCruiser this season. Spraying some cleaner/gum reducer in the carburetor helps, but it still idles a tad rough. When you use an additive like the one made by ValvTech, and run a half-hour with a full tank of just-pumped 89 octane, the idle is back to where it was last season. It's hard to say for sure if it really did anything, but the idle has certainly smoothed out.

Spark Plugs.
If you're like most boaters, you change your spark plugs at least every season and use regular copper-core plugs that probably cost the least of anything you buy for your boat. Then there are platinum plugs. There are many manufacturers that claim that the platinums maximize efficiency. Platinum plugs have three or four times the longevity of copper plugs because they virtually eliminate that electrode destruction.

When you're installing plugs, gap the mat the minimum gap the plug instructions of your engine manual calls for. The gap between the electrodes will grow because the center electrode (or both) is slowly being eaten away each time it sparks. As the gap grows, there's more electricity that is required to bridge the gap, and then eventually the coil isn't able to produce what's needed.

One last note on plugs: There are some mechanics who feel that split plugs
(a double electrode sort of system) may not be too healthy for both the pistons and chambers. Consider this to be your warning.

Wires. While checking out your rough-idling engine, you think back to the last time you changed your spark wires. After looking in your logbook and receipt file, you discover that it's been at least three years. Not smart.

Spring for an upgrade here. If you can deliver the power with better conductivity, while shielding the lines from heat generated by the engine, you'll get a better spark on the business end. Magstar wires are said to deliver up to five times the conductivity of original equipment manufacturer (OEM) wires. They use a proprietary 'mag wire conductor' (a stainless-steel wire that eliminates interference problems with electronics), a pure silicone jacket that is self-extinguishing in the event of a fire, and stainless-steel snap-lock terminals to ensure a positive hookup. When replacing wires, change
only one at a time to avoid altering the firing order.

Props. One place you actually can pick up some extra go is from your propeller. If you're running an aluminum prop, go for a stainless-steel one, which provides a power increase at three to four times the price of an aluminum prop. The main reason is that stainless prop blades are much stiffer than aluminum blades. For more upper-end speed and acceleration, go for a propeller with a higher pitch. Need more power to pull out, say, wakeboarders quicker? If this is the case, then you should go lower pitched.

Diameter and pitch are correlated with your engine's maximum rpm at wide-open throttle (WOT). You'll find the rpm range at WOT in your engine manual. This is key to the longevity of your engine. Make sure whatever prop you go for keeps the rpms at WOT within the engine's operating parameters. The wrong prop on an engine will kill it prematurely.

Hull. The interface with water causes most performance degradation, because your hull plus water equals friction. And there's really not too much that you can do about it.

The Naval Research Laboratory has been trying to duplicate what a dolphin's skin does in water. The original testing revolved around antifouling technology, but that's but a hop, skip and jump from speed coating. At some point in the future, advances in carbon, resin and ceramic technology may come up with a coating that'll be affordable, durable and actually work. For now, you have to consider that with all of the coatings that are on the market, none are banned by the respective racing organizations. And if it isn't banned, how well can it work?

You may gain a mile an hour off of some coatings, but consider how long it'll last and whether that mile an hour is worth the effort of applying something. For most of you, it'll be a case of keeping the hull cleaned and waxed. For those who are in the water all season, make sure your antifouling is up to par ... and wait for the aforementioned microtubules.

Bottom line? Smart, regular maintenance works. There are no big secrets to keeping your boat running at its best. For next month's project, you might consider mounting a nitrous oxide kit ' nah, just kidding. First things first.

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September 2004