Could be that those numbers refer to the Gross registered Tonnage, which is an old measure of interior
volume based on 100 cubic feet of volume being 1 ton. In your case that would be 496 cubic feet of interior
space. Main Cabin
, locker and Vee berth, forepeak and engine
room. That seems about right. I had my Grampian
26 measured once and it came out to about 3.9-4.1 tons if I can remember correctly. If you subtract the forepeak, engine
room, and head
, you get the Net registered tonnage, which is the cargo volume you could carry. Long time ago, the memory is getting a bit fuzzy on that.
I'd say the displacement
weight being 6,000 lbs is reasonable in your case. The Gramp was 5400lbs. Espina has a Gross of 7.85 tons, net of 7.28 and weighs in at 15,500 lbs. Sabre
Dance has a Gross of 13.63, net of 13.33, and weighs in at 20,800 lbs if the crane scale was correct.
Best way to find out displacement weight is to take her to a highway weigh scale. Then launch the boat and reweigh the trailer/cradle or what ever.