Progressive is a very good deal. I just shopped around and found that progressive gave me the option of full boat replacement and I pay $300 a year for a brand new $17,000 Sea Hunt with a 115F motor. I couldn't pass it up.
Don't quote me, but I believe it is optional. However, most marinas will require you carry insurance. Not to mention the fact that with all that can go wrong on the water, you'd be crazy not to have insurance. Tight lines.