Boat insurance is usually required if you keep your boat in a marina and, like auto insurance or rv insurance, provides liability protection in case of an accident, and may protect your investment in your boat. Liability insurance protects you and the marina operator and your fellow boaters if there is an accident in the marina or on the water. Requiring liability insurance also protects you by making sure other boaters have coverage should they cause an accident that damages your boat or injures you. So the insurance requirement is both understandable and reasonable. Including comprehensive or "full coverage" protects you by paying for the damage to your boat if you are at fault in an accident or the boat is damaged by storms, uninsured boaters, etc. and is usually required by the lender if your boat is financed. If someone else is at fault when your boat is damaged they should be liable for repairing your boat.
One thing I noticed when I purchased our boat insurance was it asked for a "declared value" for the boat. The declared value will be the most the insurance company will pay out if your boat is totaled. You may want to verify the value of your boat from time to time. I used what I had seen as asking prices for similar boats to determine the value of my boat, but that was prior to investing a considerable amount of time and money in fully restoring both the boat and the trailer. Once that was done I should have increased the "declared value". A couple of years later a problem with the trailer dumped our 24' sailboat onto the pavement on the way to the lake, destroying both the mast and the swing keel. Since it is a vintage boat, replacement parts are somewhat difficult to come by and the estimated cost of repairs quickly exceeded the "declared value" of the policy. Re-evaluating the value at the time of annual renewal to account for the reconditioning might have given us a larger margin for repairs or replacement. The real market value of a boat is likely to change over time. Usually, like most other personal assets, it will probably depreciate. A lower declared value might lower your annual premiums, but not always. The default for declared value when I insured my boat was $10,000. I reduced the declared value, hoping to lower my premium, but the premium remained the same and at that point the web page wouldn't let me change the declared value back to the default! If, by chance, your boat increases in value due to improvements or market demand, you will want to increase the declared value to ensure adequate coverage to repair or replace it if something does happen to it. If you can't do it on the web, call an insurance agent.
Boat insurance may also include an allowance for personal property. This allowance covers anything you might have in the boat -- clothing, bedding, tools, special equipment etc. It would behoove you to keep a record of the personal property together with receipts or other proof of cost in case it is lost or damaged in an accident. The electronic navigation equipment and other modern electronic amenities are often quite pricey, so having receipts showing the value is worth the hassle if you ever need to file a claim.
The amount you have to pay for boat insurance will depend on several factors, including but not limited to the type and value of your boat and where it is normally kept along with the coverage you select. You probably won't find as many carriers who offer boat insurance as there are that offer automobile insurance, but you should still be able to shop around to get the best value. Always look at the coverage as well as the premiums. Getting the lowest price does not always mean you are getting the best value.
On the water towing is an option often offered along with your insurance. Before paying for on the water towing, make sure such services are available where you use your boat. You will probably find them at most ocean harbors but they are less frequently found on inland lakes. No sense paying extra for a service you can never use!
Making a claim is about the same as making a claim on your auto insurance. Call the phone number on your insurance card. You will need your policy number, the year, make, and model of your boat, the date, time, and location of the accident, a detailed description of the accident, and the names and phone numbers of any witnesses. You may also be asked for a police or law enforcement case number so the incident should be immediately reported to the proper authorities. In many cases making a claim can increase your future premiums so you don't want to file a claim for trivial damage, even if you have a zero or low deductible. If your boat is financed the lender will want to make sure it is properly repaired.
Insurance is good to have if something unexpected happens. But, of course, it is always better to avoid accidents in the first place. Keep all of your equipment in good repair and inspect it before each use. Avoid operating your boat or towing it when under the influence of alcohol, drugs, or medication or when you are unusually tired or stressed. Always be alert to conditions around you and plan ahead for what you will do if something threatening occurs. Our accident was caused by failure of one of the bunk boards the boat rested on on the trailer. They were only two years old and I had upgraded them from the original 2x4's to pressure treated 2x6's for an extra margin of safety. Why one of them failed is still unknown, as they were made of treated lumber and were largely protected from weather since installation. Perhaps a defect in the integrity of the tree they were cut from I guess. Maybe a closer inspection of the boards when I purchased them might have prevented the accident -- if the flaw was visible.
Ensure that you are properly insured!