Good questions Steve.
I've had insurance coverage for smaller boats with State Farm, my auto insurerer, and found them to be OK. When it comes to claims, they're not really set up for boats so, if you have a claim, they use an independent adjuster. At least that's the way ot was when I insured with them, but it might have changed. I've had coverage with BOATUS for many years. They're a little like the FMCA//GoodSam/CampingWorld of boating and they're set up to cater to the needs of boaters. Their insurance division really understands boaters' needs.
Coverage is typically for a year. I don't discriminate between a boat in storage or one in use. The boat can get damaged either place and someone can get injured either place.
Coverage usually states "normal cruising waters", but can be extended with a phone call. e.g. ours states San Francisco Bay and delta, and some distance offshore up/down the coast. When we went down the coast to Mexico I merely made a phone call and they extended coverage for free, although I got the impression that, had we planned to go further, there would have been additional premium.
Some small boats are covered under a larger boat policy as a dinghy/tender, but this courtesy varies with insurance company.
