The
advice regarding consulting an accountant is good. There are specifics to every situation. There is a 5 year carry over for excess, but there are other limitations, including the donor's adjusted gross
income (in each of the carry over years). The limits for property may be different to those for cash, and different types of 501(c)(3), such as private foundations vs. public charities, incur different limits for cash or property.
So you really do need to have your specific case reviewed in the context of the donor's AGI and the type of 501(c)(3). As far as value goes, it just has to be fair market value. You can prove this by providing listings of similar or identical
boats for sale at the time of transfer, but an independent, formal appraisal is surely a lot better.
Pete