Why Do Outboard Powerboats Sink?

One Hint: Look to the Sky

In the first of a four-part series looking at the causes of recreational boat sinkings, the July issue of Seaworthy, the damage-avoidance newsletter from BoatU.S. Marine Insurance, took a close look at the claims files and identified the myriad reasons why outboard powered vessels sink.

This study can help boaters learn from other's mistakes and provide boat owners with more specific information on how to protect certain types of vessels.

The research confirmed that most boats sink while tied up at the dock, outnumbering sinking-while-underway claims four-to-one. Nearly half the outboard powered boats that sank at the dock were victims of heavy rain or snow.

Ironically, almost all had "self-bailing" cockpits. The results are as follows:

Sinking At The Dock
Rain/snow 47 percent
Underwater Fittings 20 percent
Above the Waterline Fittings 10 percent
Poor Docking Arrangements 9 percent
Water Over Gunwales/Transom 9 percent
Other 5 percent

Sinking While Underway
Water Over Gunwales/Transom 32 percent
Livewell/Baitwell Plumbing 20 percent
Drain Plug 16 percent
Struck a Submerged Object 12 percent
Other 12 percent
Construction 8 percent

Seaworthy Associate Editor Chuck Fort said, "If you want to reduce the risk of your outboard powerboat sinking at the dock, the best way is to use a good-fitting boat cover that keeps out precipitation.

Also ensuring that Marelon or bronze fittings are used below the waterline can reduce your risk. This is a more common a problem on a used boat when a new owner may be unaware that a previous owner unwittingly installed a plastic fitting below the waterline that eventually degrades and cracks.

When underway, outboard powered boat owners should be concerned about swamping from the transom. Transom wells are sometimes poorly designed and every effort should be made to prevent water, even from the boat's own wake, from entering the cockpit or bilge area."