3. Scuppers in the Winter
What Happened: White stuff fell and ice built up around the scuppers, filling them in. Since this occurs under the snow, you can't see it. The good news is that once the boat sinks, the ice will melt.
What You Should Have Done: Haul out for the winter, or have a waterproof, reinforced cover that can take the weight of accumulated snow. Don't treat your boat like your mother-in-law: Visit it often.
4. Scuppers Anytime
What Happened: A piece of plumbing corroded, cracked, or just gave up. The weakest link is the hose that can crack, most often around the stress points created by the clamps.
What You Should Have Done: While the boat is on land, check the hoses by flexing them back and forth. If there are any cracks, replace the hoses.
5. Hose Clamp Failed
What Happened: A hose attached to a seacock below the waterline, or a through-hull just above it, came off its fitting because the hose clamps gave way.
What You Should Have Done: Secure each hose with two clamps where it passes over the fitting's nipple. Check that the clamps are all stainless steel (a magnet won't attract stainless). Often, the tightening gear and its case are mild steel, which rusts away.
6. Trapped Under a Dock
What Happened: You tied up the boat at low tide. The wind pushed part of the boat under the dock, the tide came up, and the boat became trapped beneath the dock, then sank.
What You Should Have Done: This can happen when the pilings supporting the dock are too far apart to keep the boat parallel to the dock and out from under it. No matter how many docklines you rig, this will be a problem. If you can't dock somewhere else, set anchors out from the bow and stern so the boat won't swing.
7. Tied Down, Tide Up
What Happened: At low tide, your bow and stern lines were tight. When the tide came up, the lines stayed that way-firmly holding the boat down as the water rose.
What You Should Have Done: Long spring lines attached at acute angles to the boat adjust as the boat rises and falls. Bow and stern lines may have to be tended as the tide goes through its cycle.