Dave- your link was broken, but it gave me just enough info to point me in the right direction.
For any that are interested, here's the full text of the Harmonized Tariff Schedule:
You can look up the schedule for sailboats (with or without auxilliary motors) at section 8903.91.00. As long as the boat wasn't manufactured in Laos, Cuba
or North Korea
, you will pay at most a 1.5% tariff (based on value).
If the boat was manufactured in certain countries (South Africa
was already provided as an example, also Canada
seem to falll into this category), there is no tariff at all.
Interestingly, inflatables (section 8903.10.00) are tariffed at a higher 2.4% rate.