Whether you realize it or not, every boat, from a big cruiser to a personal watercraft is a potential houseboat. That is, what you do with your boat in a split second could create a liability that could cost you your car, your life savings, or your house. It happens all the time.

That's why the next few months, when you're winterizing your boat and doing preventative maintenance to protect your investment, is a good time to do something to protect yourself. Do some basic insurance shopping, getting what some underwriters call an "insurance checkup."

Granted, insurance is deadly boring stuff. I used to think the salient statement about insurance was a scene in Woody Allen's Bananas in which a prison inmate who had really messed up was subjected not just to solitary confinement, but solitary confinement with an insurance agent, who did his spiel non-stop while the recalcitrant prisoner was in the hole. (How cruel and unusual can you get?) But I stopped laughing off boat insurance when I heard about a guy who had to sell his house to pay off a judgment from a boating accident in which he was at fault.

Fact is, you can get liability coverage that will cover you up to $1 million for as little as $20 a month, and there are all kinds of creative insurance resources like your homeowners or renter's insurance policy that can help you if you know how to avail yourself of them. Insurance is an area in which you can not only save hundreds of dollars on your premiums, you can potentially save tens of thousands of dollars in potential liability by doing a small amount of research when you are shopping for a policy.

You can rely on some basic information that you've probably learned as an auto insurance consumer. In boat insurance, just as in car insurance, bigger, fast more expensive in terms of what is being insured usually means bigger premiums as well. Some insurance companies have about as much of an affinity for a sleek high-performance boat as car insurance companies have for a souped up Corvette, which means that you should factor in the fast-boat surcharge effect when you are shopping for a boat. "How much will it cost me to insure this boat?" is a very pertinent question to ask from the first moment you spot a craft that catches your eye in the boat yard. And while your boat dealer can give you some straightforward and useful information, it's a good idea to also seek out more objective sources.

Two good sources are BoatU.S., the Boat Owners Association of the United States, (703) 823-9550 or the Insurance Information Institute's National Insurance Consumer Help Line, (800) 942-4242, at which you can get free information and advice from an insurance expert who won't try to sell you a policy. BoatU.S. is a boating advocacy group that also sells insurance, but being primarily a membership group, it has policy of not being pushy about selling coverage.

Jayne Neagle, a spokesperson for the Insurance Information Institute, says there's no substitute for putting in a little work in your quest for insurance knowledge, and this it will usually pay off big-time. "You should not only ask the boat dealer, but ask your friends who own boats, find out if there's a U.S. Power Squadron or Coast Guard Auxiliary in your town and ask them about it; talk to people who have experience and can be objective."

The good news, Neagle says, is that boat insurance is relatively cheap. You can get coverage for a $25,000, 25-foot boat for $500 to $900 a year, or $40 to $75 a month — not that much when you consider that you've got a $25,000 investment to protect, and the potential for liability that could go 40 times that high. Most basic boat insurance policies include liability coverage of $200,000 to $500,000; you should ask the specific amount before you sign up, and you can extend that cheaply through your homeowners policy. A basic boat policy is also like car insurance in that it covers replacement of the boat and its contents, as well as medical coverage for you and your passengers. But insurance experts stress that you can't just assume you're getting that coverage. You have to ask all the specifics to make sure it's all in the policy.

With a homeowner's policy, you can get was called a "liability umbrella" of up to $1 million for about $200 extra in premiums or $16 a month. That liability coverage not only extends to your boat, but any other source of personal liability — the classic neighbor-slips-on-your-sidewalk scenario. One of the big new liability areas for boats is environmental damage. You don't have to be the Exxon Valdez to run up a big oil spill bill. Under current federal laws, any individual can be held accountable for up to $500,000 in damages for an oil or gasoline spill. All BoatU.S. boat policies automatically carry $500,000 environmental liability coverage, and you should ask about that when shopping for a policy.

In terms of basic property damage coverage, you may have $1,000 or so on your boat through your homeowner's policy and not know it. If you boat is small, 50 horsepower or less, and relatively slow, your homeowners policy could easily kick in $1,000 if it sinks or is stolen. Check with your agent.

One of the best new trends is boat insurance that not covers your safety, but serves as a buddy system to keep you from being inconvenienced. A number of insurers offer towing coverage for a minimal charge. On several occasions when I've found my boat lodged on a sandbar, I've simply picked up the VHF, called the BoatU.S. affiliate, and been towed off the sandbar quickly enough not to miss getting ashore for lunch. Once, in Biscayne Bay, I called BoatU.S. because I couldn't make the kill switch work on a boat I had chartered. I was a little red-faced when the guy from the towing service turned off the engine 30 seconds after he came aboard, but I was not sorry I had called him.

The newest line of insurance coverage does what a dealer's warranty does, only it does it a lot longer — covering repair costs that in many cases may be inevitable.

"Essentially what you can do," said Doug Semler of the Old United Insurance Companies of Merriam, Kansas, "is extend what your manufacturer's warranty would cover from one-year to almost six years, because we offer five-year coverage that you can buy for a boat up until the boat is 11 months into the original warranty." Blown gaskets, stripped gears, torn-up outdrive, the mechanical breakdown insurance covers it all, and can save you thousands on repairs. Typical cost is $650 to $900 for a 25-foot boat. There's a cruiser package that even covers items like your boats refrigerator for five years.

The only thing the breakdown insurance won't cover is replacing your prop. Anyone whose spent much time in a powerboat knows that would be like insuring that your ice cubes won't melt. But when you do break a prop or a sheer pin, towing policies that cost as little as $75 to $150 a year will make sure you've got a towing service to come out and help. In the case of BoatU.S., towing coverage is included in your membership, not your insurance policy, so frequent usage of the towing service doesn't make your rates skyrocket. If it did I'd be in bankruptcy by now. Fortunately, I did what every boat owner should do once a year or so — some insurance research, and I read the fine print.