I'm so sorry for the circumstances.
We have never donated a boat, but have donated two cars to Recycle For Gold (Special Olympics). They picked up and sold the vehicles at auction. We got a receipt after they sold the vehicles so that we could write off the donation on our taxes.
Honestly, if either vehicle had been in decent shape to sell, we would have been better off financially to do that rather than donate. If your boat is in good condition, you will probably be better off selling than donating, even if you have to take a hit on the price.
Hang in there and hoping that things turn around for you soon.