You should insure against low risk but high financial loss if it something happens. Likely low insurance premium to value ratio.
You should self insure against high risk but low financial loss if something happens. Likely high insurance premium to value ratio.
So for a domestic washing
machine self insure because it will break down but the cost of a new one pretty low.
However, the loss of even a modest yacht will be significant, so insure against it as the annual cost is tiny compared to the value of the yacht. Think we pay 1% for coastal cruising in NW Europe
. You pay a bit more in the US I believe 1.3 - 3% I seem to remember from previous threads.
However, for a marina berth other than a short stay, they often ask us about insurance cover and who with. For our permanent berth we had to provide a copy of the policy.