Another consideration... If the total value of the boat is only $4,000, do you need to insure it at all? If it was a total loss, could you afford it? I'm assuming it is paid for and there is no loan on it.
I paid $4,000 for my boat and motor. Safeco insures it for boat/motor loss, medical per occurrence, onboard equipment, etc., and most importantly, liability ($500,000) for $23 a month. $250 deductible. To me, that's a great deal.
I don't have the cash to go out and outright buy another $4,000 boat in case I lose this one. I'm Po People.