: Hi John,
: It does look like there's a fourth batten on that sail in the angled 'seam'
: going from luff to clew at the bottom. The next seam up is just a seam.

: Usually a sail for lower wind speeds will be fuller in cut, about 10% of the
: luff to leach measurement. The deepest point of camber is between 33% and
: 40% back from the mast. Single sails benefit better with closer to the
: 40%, the air flow seems to 'stick' better to the sail.

: Mike Savage
: South West Cork

Hi Mike
10% of the luff to leach would give me 5 inches of depth. That will give me something to shoot for to start with. I am making a 1/8th scale model sail out of Tyvex house wrap (those big shipping envelopes you can’t tear) you can get in the US post office’s,,,,, and with battens to see what the characteristics are. I can check to scale the chamber belly.

The reason I think the bottom of the sail may not have an angular batten is some of the Balogh sails have a zipper reefing and it would seem the bottom batten would have to be taken out each time you reefed. I’m not sure of that but it looks like if the batten was left in that it would bind as you dropped the sail. But I can’t think that through very well. Maybe the model will give me the answer. Thanks.

John