"Whether car/truck/boat/motorcycle.....you WILL have a next to impossible time EVER insuring that boat again. Insurance companies will NOT pay twice. Once totaled, they - collectively are done with that item."
Not so simple. What an insurer will do depends very much on whether the vehicle involved was issued a "salvage title" and what the reason for the "total" was.
I had a car that was totalled because of theft, too many parts stripped. The insurer saved a few bucks by not forcing a salvage title, which is hard to remove in many states now. So the original title was never changed and once I had the missing parts restored and the vehicle re-inspected, they picked up full insurance again without any discussion.
How individual insurers, and states, deal with total losses, collision or otherwiwse, and how titles are changed, is very much an individual matter. If your state requires a salvage title, the insurer still may or may not bother with it. And some states (notoriously) make it very easy to clear a salvage title while others require special reinspections. I'm sure they make it easier on boats than on cars--but this is by no means a uniform process in the US.
And that's probably logical, too. After all, if I spend $2000 for parts, and four days of my time installing "modifications", the insurer will only recognize the $2000 added. If a SHOP does the job and bills out another $3500 in labor fees--the insurer will recognize the total of $5500, because money changed hands. If you make repairs by yourself or find some discount labor source, that's to your advantage. They pay "book" rates, they know you have the option and sometimes ability to beat those.