With the advent of modern fiberglass boats, mariners are no longer nagged with fear that a weak plank, or rotten rib will send their vessel to the bottom. Hull integrity is no longer the concern that our predecessors worried over, just a few decades ago. Yet every year, tens of thousands of boats sink, most at their own dock. This is the leading causes of large insurance claims and the reason you pay too much for your insurance. And, most of the time, it is entirely preventable.

Why do boats sink? Some result from collisions with other vessels, objects in the water, the bottom, or a fixed object, such as a piling. Other obvious causes are over-loading or not properly balancing load inside the vessel, causing it to take water over the gunwale and swamp or capsize. And there is neglect, such as permitting a boat to fill with rain water in a storm, forgetting to install a drain plug, or allowing scuppers to become blocked. Add to that list, poor anchoring technique. An single anchor hung off the stern in a rough sea is asking for it.

But bad design also contributes to the problem. In small boats, cockpit decks are often placed near the waterline to provide adequate height at the gunnels to prevent crew members from falling overboard. This low deck placement allows water to enter through scupper holes, particularly when flappers are worn or encrusted. Under normal conditions, the water will not travel far and will run back out, but when overloaded with fuel, water, people, and equipment, or if the boat is improperly trimmed, the deck will sit below the waterline, inviting more water and disaster. Is your deck less than 4 inches above the waterline with full tanks? Try putting three adults in one corner - does the water runs in? If you answered, "yes" to either, you should plug your scuppers and add redundant bilge pumps.

Deck hatches, with broken or dirty seals, also contribute to the problem. Always assume that a sealed compartment might become "unsealed" and make sure that the compartment contains a bilge pump or drains to another compartment that does.

Boats without an adequate transom, or with non-sealing transom doors invite water rushing onto their deck in heavy seas, rough inlets, or during sudden stops. Owners with these configurations should consider carefully where, when and how they travel with their boats.

Internal systems are also accountable for a number of sunken vessels.

• Improper overboard plumbing will allow reverse-siphoning of water into the boat.
• Inadequate or faulty bilge pumps, switches, wiring, or batteries will compromise this vital safety system.
• Damaged, corroded, or worn through-hull fittings, hoses, and hose clamps provide an easy entry point for seawater.
• Worn rubber boots connecting muffler exhausts, or surrounding out-drive cutouts exact their toll every year as well.

So now is a good time for some routine maintenance. Check your vessel for sea-worthiness. Remove rags or other objects that could wash around in the bilge and clog the bilge pump. Check hoses, clamps, fittings, seals, scuppers, batteries, pumps, and switches.

One trick to remember in a dire emergency for inboard vessels: the raw water hose can be cut or disconnected from the through-hull (as you close the valve) and used to suck water out of the bilge through the engine's raw water pump.

Sailors with only one bilge pump should consider a backup, such as a Rule 3500 for extra protection; and sailors check those sink and head drains to insure they don't take on water in a healed-over position.

Remember, the Coast Guard Auxiliary offers free Vessel Safety Exams to help you stay safe on the water.