PWCs are vessels — paper them like one
Jet skis, WaveRunners, and Sea-Doos register as boats in most states, which means the registration office will ask for a bill of sale carrying the hull identification number (HIN), stamped on the rear of the hull near the transom.
What to write down
Year, make, model, HIN, and engine hours from the gauge cluster. If a trailer is part of the deal, say so explicitly and include its VIN — many states register the trailer separately at the DMV.
Water test before you sign
A PWC that idles fine on the trailer can still cavitate or overheat at speed. Do the water test first, then fill in the price and sign — the as-is clause in this document means what it says.