While you may never expect to file an insurance claim on your boat, knowing why and how damages occur can help you reduce your chances. The January 2006 issue of Seaworthy, the damage avoidance newsletter from BoatU.S. Marine Insurance, reviewed five years of its own claim files to find the most common causes for insurance claims. Both the individual number of claims, as well as insurance claim dollar amounts, were factored in to compile the list.

1. Striking submerged object: Nationwide, striking a submerged object is the most common incident that leads to filing a claim. The amount of floating debris increases after major storms or extreme tides so be extra vigilant after these events. Unfortunately, striking an object sometimes leads to a sunken boat claim; check the bilge immediately after a strike and frequently thereafter.

2. Sinking: Lesser fittings like hoses and clamps only last a few years and often fail long before the beefy seacock they are attached to. Outdrive bellows over five years old are on borrowed time and rainwater improperly drained into the bilge by clogged scuppers kills your battery and bilge pump.

3. Fire and explosion: The number one reason for boat fires is DC wiring faults, with the most common fault being chafed wires, usually as the result of poor support or insecure attachment. AC shorepower cord inlets are another prime area as wear and corrosion cause resistance, which creates a lot of heat. Corroded, overheated exhaust manifolds and fuel leaks bring up the bottom of the list.

4. Wind and weather: Sloppy weather happens everywhere. Minimizing windage, tying up securely, guarding against chafe and staying protected help reduce storm damage.

5. Collisions: Collisions with docks or pilings are common but collisions with other boats are more serious. Inattention, blind spots and too much speed most often are the culprit. Out on the water, misunderstandings of the rules of the road are most often cited, but know that it takes two skippers to be in one bad spot at the same time.

6 Grounding: What you do after you've hit bottom — such as attempting to power through — often causes more damage than the initial impact. It's best to stop, carefully evaluate the situation, wait for the tide or call for help if you need a gentle pull. Also, knowing the exact depth beneath your depthsounder's transducer and its exact position relative to the bottom or your boat or running gear is very important.

7. Lightning: Since there isn't anything you can do to prevent a lightning strike, the best measure to mitigate damage is to ensure your boat has a proper bonding system that will direct the strike to ground.

8. Theft of boat: When thieves steal boats, they often strip everything of value leaving only a shell. Ninety percent of the boats stolen were on trailers, so removing tires, installing a coupler lock and parking in a well lit, secure area can help.

9. Theft of equipment: Make time-consuming "work" for a thief, and they will likely go elsewhere. The theft of outdrives can be prevented by adding hefty locking nuts; the same goes for outboards and trailers. If they can be removed, expensive electronics should be stored under lock and key — and at home in winter. Well-lighted storage or marina facilities with security measures are the best deterrence.