Another day of festive eating under my belt, so hopefully now back to normal and the post-Christmas diet.
I agree that small boats should not need additional panels for local sailing, but I asked the question at the start of this thread in an effort to encourage lateral thinking, and thoughts on the best sail area for sturdy rigs for long distance cruising boats.
I did have an idea which I'm offering very much with tongue in cheek.
If a boat is cruising long distances and wants more area in very light conditions then is might be practical to have a simple well cambered topsail, built with round and broadseam or angled shelf foot out of spinnaker material, and attached to a light weight yard. With a single block at the mast head for a light weight endless halyard, and an eye attached to both ends of the normal yard it would be a case of -1, dropping the rig, 2, attach clew and tack of the topsail to the normal yard, stretching the foot of the panel tight, 3, attaching the halyard to the topsail yard, and 3, with the topsail hanging down on the outside of the rig re-hoisting the rig. Then to raise the topsail, 4, simply haul the topsail yard to the peak.
If there is not enough mast then the topsail yard could be attached to a stub topmast which could hoisted by the light halyard and kept erect with the halyard downhaul.
The diagram below shows a topsail on the Mk2 Amiina drawing, and adds about 15% sail area.
Also in the drawing was the other idea I was hoping someone would suggest, and it's interesting the Graeme did. I would call it a watersail, but really it is just another panel to stop the wind escaping under the rig and making the hull effectively an end plate. It might add another 15% area, but it would reduce the inefficiency of the pressure loss below the sail. This is the easier option of the two, simply requiring a broad-seamed top edge and clipped tightly stretched along the bottom batten, and tied down to a few points on deck with no spars required. The only refinement would be the need for windows in the panel.
OK, I'm not fully serious with these suggestions, but am offering them as points to ponder.
Cheers, Slieve.