An engine can impart tremendous strains on a boat's hull. Hard Service: Boats that punch through or fly over waves need a durable mounting system. This can include bolting the engine to metal channels or brackets, which in turn are bolted through the engine bearers. (Bearers are beefy stringers that support the engine.) Moderate-to-Light Service: The engine's mounts are lag bolted directly into the tops of the bearers. Severe vibrations and shocks can work the bolts loose, which can cause engine-alignment problems.
The same vibrations and hull shocks also affect the fuel tanks. Their mountings are usually difficult to inspect. Your best chance of seeing them is often by looking at them through the engine room. Hard Service: You should be able to tighten any slack in the hold-down straps by using turnbuckles. Plus, every place the tank comes into contact with the boat should be cushioned. Moderate-to-Light Service: If you're not pushing the boat to its limits, a tank chocked in place with wood beams is acceptable. One improvement to consider is to have each corner held in place with a bracket and then have padded metal straps placed over the tank.
The hoses leading from the tank are another good indicator of how well a boat is manufactured. This is an easy place for a builder to skimp without being obvious. Hard-to-Moderate Service: You might find pressed-on threaded fittings. Stainless-steel hose clamps are adequate, and only slightly less secure. True stainless won't attract a magnet and is easy to check. Light Service: On the low end, bordering on dangerous, are plastic clamps.
After the hull itself, it's a boat's plumbing system that keeps it afloat. For easy inspection, we suggest starting in the engine room. All Services: All through-hulls that are below the waterline must have a seacock (a combination through-hull and valve). We prefer the bronze ball-valve type. Seacocks made of the composite Marelon can be safe if they're stamped UL Approved. Their primary weak spot is the lever, which can break. Our advice? Stick with bronze. Seacocks should have glassed-in backing plates where the fitting passes through the hull. If the hose connected to a seacock comes off, your boat will sink. We recommend two hose clamps at each end.
If water does get below, your only hope is the bilge pump. The centrifugal pumps found in most boats often have high, 2,000 or more gallons per hour (gph) ratings. You must realize, however, that this is misleading. Their flow rates can be cut by almost half if they're required to raise water higher than six or eight feet. Hard Service: Look for multiple pumps, high gph, intake strainers, smooth-bore hose, and an anti-siphon loop of the exhaust hose if it's close to the waterline. Moderate Service: A midlevel (1,500-gph) automatic pump with corrugated hose is acceptable. Light Service: Only boats that live on a trailer can get by without an automatic bilge pump.
Automatic pumps need switches. Hard Service: Look for a solid-state switch mounted high and out of reach of any bilge water. Moderate Service: A flapper-style float switch is fine. Light Service: If the pump has an automatic switch, it's built in.