I got a quote (see quote attached below) from Progressive which is who we had our 180 Challenger insured with previously, when the quote came back it was a lot higher than I expected. I bumped it up to a $1000 deductible to see how this would affect it, but still that didn't make much difference - it was $1039 per year.

I then decided to get a quote (see quote attached below) from Boat U.S. to see how they compared. To my surprise they were almost half what Progressive was quoting with lot less of a deductible. Their dedectible is typically 1% of the insured value so it made it $450 for our policy. The quote came in at $553 per year which was much better so this is what we went with.

When comparing the two I kept the coverage amounts the same so I would have a "true" comparison in the quotes. Even keeping them the same it seemed that Boat U.S. offered some better options than Progressive. To quote the rep I spoke too he said, "This is what we do - insurance for boats, we don't insure anything else". With this statement I believe he was trying to tell me that while other companies out there offer boat insurance it doesn't mean this is their expertise.
It is worth a shot, if you don't already have Boat U.S. for insurance, get a free quote and see if they can save you any money!
Please let us know if you end up saving any money, we would like to hear about it.