Keeping Your Boat Afloat

An analysis of a year's worth of sinking files reveals the 10 most common reasons that boats end up under the water.

By Beth Leonard
Published: April 2014
These 10 items address the 10 most common causes of sinking in our year of claim files.

1. Inspect your sterndrive bellows annually and replace them every 3-5 years.

Photo of severed exhaust bellows

The bellows on sterndrives are required to remain watertight for years while withstanding flexing and bending, exposure to water and marine growth, and extremes of temperature. Talk about a difficult job! The shift bellows is the smallest, which makes it most susceptible to cracks that start in the folds. By tilting and turning the sterndrives, you can inspect the bellows, and this should be done annually. Marine growth can puncture the bellows, so remove any that you find. Replace the bellows if you see any sign of wear, but at least every five years. If one bellows is worn, chances are all of them are, so replace them as a set.

2. Check your stuffing box every time you visit the boat; repack every spring.

Photo of water entering shaft stuffing box

Stuffing boxes are one of the few thru-hull fittings designed to allow some water into the boat, at least when the motor's in use. But it's way too easy for that one to two drips a second to turn into a stream. The only way to prevent it is with diligent maintenance, repacking the stuffing box rather than simply tightening down the packing screw again and again, and possibly damaging your prop shaft in the process. And make sure to check your stuffing box every time you visit your boat. If the bilge pump is running regularly on an older boat with a stuffing box, you can almost bet that it will be the source of the water.

3. Replace your engine raw-water hoses at the first sign of wear.

Photo of a ruptured water hose

A ruptured raw-water hose or one that has come off a fitting due to a corroded hose clamp or deterioration on the end of the hose can sink the boat at the dock if the problem is below the waterline. But even cooling hoses above the waterline can bring lots of water into the boat if the problem is downstream of the raw-water pump and the engine is running. Hoses should be replaced at the first sign of wear with the appropriate type and size. If your hoses are 10 years old or more, why not give your boat a spring treat and replace them before putting the boat back in the water?

4. Replace your impeller every 2-3 years.

Photo of exhaust hose failure after engine overheat

Your cooling system can sink your boat without even springing a leak. If your impeller deteriorates due to age and wear, the amount of water it can move through the water pump will decline and eventually it won't be pumping anything at all. Well before that point, your engine will overheat. If you don't shut it down right away, the hot gases can melt the hose, allowing water to enter the boat. Changing your impeller every few seasons — whether it needs to be or not — is cheap insurance indeed.

5. Make cockpit and live-well plumbing accessible and inspect regularly.

Photo of a cockpit drain fitting
Photo of a hose off cockpit drain fitting

A large cockpit is nothing more than a bathtub when rain starts to fall. If the cockpit drains don't do their work, the boat can be overwhelmed by a heavy downpour. Problems in the claim files include missing hose clamps, broken drain fittings, broken thru-hulls, and loose hoses. In several small powerboats, hoses were never fitted to drains when the boat was built. It pays to inspect everything from the drain to the waterline at the beginning of every season. And don't forget live-wells, bait wells, and fish boxes. Inundating suspect areas with a hose and seeing where the water goes will uncover any problems. Unfortunately, on many boats all of these drains, hoses, and thru-hulls can be difficult to get to. If that's the case on your boat, you'll have to create access and cover the openings with watertight deck hatches.

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