The Whitehall is a thing of beauty for a fiberglass rowing vessel. They are strong and ridged enough so that your rowing energy equates into forward motion, sort of like how a good racing bike uses its energy. The 17 footer would be the only way to go for your needs. The sliding seat is nice for rowing but would be messy for other activities like pulling pots, moving parts and clam shells, seaweed don't mix. The sailing 17 would be really fun, can row too, I would even come out and show you how to sail it if you got one. I still think if you plan on leaving it in the water for the season you should go with wood. There must be hundreds around New England for sale and in good condition. With wood there is more maintenance but it is wonderful work to do in the off season, really helps make life more pleasant in getting through winter. If you got the 17 footer passage maker we could sail it up to Nova Scotia.