[SteveH]

I own a 17 ft. Montauk (since 1996) and the ride is very rough. Before I bought my 2000 23 ft. seacraft which is my current offshore boat, My father and I had a 1978 20' (potter built) seacraft master angler that we purchased brand new and picked it up at the factory which was in Homestead (Miami area) at the time. We had it built with a 25inch transom, which was an option. It turned out to be the right decision as we fished primarily offshore from Tarpon Springs, Florida until we sold it in 1995 (still regret the decision). I agree with Oldbluesplayer that you want to stay light if you get a 20" transom. If it was me, I would add the five inches right away if the boat you buy has a 20" transom , especially if you want to go offshore. Our hull was self-bailing. In 18 yrs. no issues - even minor ones - with the Potter built hull.
The ride on a 20 ft seacraft is fantastic and 100 times better than the 17ft. BW... Not even close. As with any old hull, make sure the transom is sound, no soft spots on deck and no issues with the gas tank.