The archive thread talks about the instability of a pygmy triple after capsize. Built one, and as a naval architect, was worried. I conclude self rescue or assisted rescue of the boat as designed would be very difficult. True, a pygmy triple is very stable and hard to capsize, but bad things have to be considered...

The 2002 thread discusses adding flotation to the sides and lots of heavy, difficult-to-build stuff. There is a simpler solution.

Adding two bulkheads makes the boat very much safer and more forgiving. I added a bulkhead forward of the front paddler's feet, and one just aft of the aft cockpit combing. Without any effort, with the new wt compartments, the boat rolls back upright with a few inches of water only. It is stable, can be re-entered and is usable in that condition. With a lift and flip, self rescue can bring the boat upright with almost no water inside. With an assisted rescue, either from the bow or stern, the boat can be righted virtually dry. More easily done from the bow.

I used the two temporary bulkheads of 4 mm ply and re-cut them to fit in the desired locations, coated in two coats of epoxy. I did not want typical deck hatches for tightness reasons, so used 6 inch hand-hold covers (deck access covers, the screw-in type) from Boat US. The forward one is in the bulkhead, the aft one on the deck just aft of the bulkhead. I also put small 3/4 in dia plastic captured drain plugs in the bottom of the bulkheads, in case I wanted to vent or drain the new water tight compartments. These were originally for a laser, but I've had them in my spares kit forever. Steering cables were installed prior to the addition of bulkheads.

Installation. I epoxied small 1/2 by 1/2 inch by 3 inch blocks to the bottom panels and the center deck panels to add structural strength to the bulkheads and hold them in place for gluing. I then epoxy-glued the bulkheads to the blocks, then made a structural fillet of wood flour filled epoxy to seal the bulkhead to the hull. Estimated total weight:less than a pound, plus a pound for the two deck access covers.

Yes, access to some potential storage volume is reduced, but I feel much safer and comfortable taking this boat out. As the coast guard saying goes, if you have to, go out but you don't have to come back. Coming back is now more certain, IMHO.