I would second the recommendation for Al Golden. I've known him for many years, and he'll always take time to answer a question honestly and openly, even on comparing policies with others.
I can't say anything about rates, but he's probably the only person I know in any business like that, who I'd call completely reputable. Whatever he sells you--it will exist and you will get that coverage, no weasels involved.
If you have any type of accident
or sink in US waters, the USCG will be on your case for environmental spills, fuel
cleanup, AND often wreck removal
costs as well. Al's the kind of guy who will tell you that up front rather than trying to sell you a cheap
policy that conveniently doesn't mention or excludes those things. He's a professional.