His problem or yours??
I think you have several choices.First - this is his boat and his problem unless and until you buy the boat and trailer. You can insist on his having the trailer fixed and the boat placed on it as a condition precedent to the completion of any sale. In addition you can specify that the risk of loss will be borne by him until the boat is safely on the repaired trailer in good condition. Under this scenario, assuming everything goes ok, when the boat is safely on the fixed trailer you give him the money and drive away with your new boat. If everything does not go okay . . . well that loud crunching sound when the boat fell while he was trying to get it on the trailer is his problem. You may want to be there to watch while he moves it to the trailer, should be a good show. ( I know I am sounding cynical here, but we all know the good chuckles we have provided to others as we learned how to do things . . and still provide from time to time. . .) Second alternative, decide what the boat is worth with the unrepaired trailer, and deduct from the price you will pay him the cost of having the boat lifted professionally onto the trailer when repaired from the purchase price. That way you transfer the cost to him. He is faced by this problem whether he sells to you or someone else so . . . . Third, buy a new trailer that you can trust for years and have the boat lifted onto it and follow #2 above on the pricing.Fourth . . . . When I got my first boat I was asked a simple question. . . Did I know the definition of a boat? The "correct" answer I was told was that a boat is a hole in the water surrounded by wood, fiberglass, etc., into which one throws endless amounts of money. That being the case, the cost of getting the boat lifted is just another one of those expenses that we all end up paying to enjoy our boats.If I sound terribly cynical here, I am sitting down this evening to write out a big check to the marina for slip fees, winter storage, lifting the boat in this summer and back out this fall, etc. . . . . Good luck and enjoy the boat.