Hi Mac,
its OAL is just on 4.7m (about 15 1/2 ft, I think), beam is 83cm. I used heavy 6mm marine ply from Bunnings (because it was cheap) and added watertight bulkheads and an extra seat in the middle instead of a spreader, so mine comes in at around 33kg - light enough to lift onto the roof of my car, but heavy enough that put it on wheels rather than carry it for any great distance. I probably could have got the weight down to around 20-25kg with a better (but more expensive) and thinner choice of ply.
It handles chop and swell just fine. I take it out in-shore on Bass Strait when the wind's not too bad and it handles little 2 foot shorebreaks just fine, and out the back is comfortable in 5 foot swells, even in a following sea (the airtight bulkheads help a lot with that). I've been on lakes in it with a couple of 20 knot blows, and it was fine with the chop from them.