If your boat is "old"
and your sailing resume is small
and your home is 3000 miles from where you will be cruising...
Surprise, the insurers will say they don't cover old boats, and you need "global" cruising area coverage since you are so far from your home waters. Establishing a Florida residence may partly address that.
Whoever insures your motorbike may cover small craft for existing policy holders--or may not cover it so far from home. Which leaves the real marine insurers (IMIS, etc.) as your goto guys. Each insurer will have different rules, a broker's value here is that they should know which insurers will cover you at all, instead of having to spend three days on the phone
There are also "gotchas" like wreck removal
and pollution abatement coverage that a marine broker SHOULD discuss with you, the complications of insuring a boat go beyond what auto coverage involves. A cheap
policy may leave you with a landmine.