I have built (and used) Bolger's Nymph pram from plans at the Small Boat Journal (now defunct). It was the first boat I had ever built but it turned out wonderfully. Rowed it in Lake Michigan swells and breaking waves and in the many ponds around here. Even tried fishing in it standing up though I wouldn't recommend it. Phil Bolger also designed a pram with a wider beam; it appears to have more initial stability. Here is a copy of the plans for the Rubens Nymph. I think the nymph pram I built would be better suited to rivers but if you wanted to stand, the rubens would be better. I built the boat in 1987 using Luan underlayment (I didn't know any better) and fiberglass tape and resin. Now I would use marine plywood and epoxy. That being said, the original pram is still usable; in 23 years I have only replaced the rub rails as the originals cracked--that's it. Since I built the Nymph, I have built 10 glued lapstrake boats. If you can saw to a line and read directions, you would have no problem building one of these; quite a fun little project.
mcsteff