First sail today! Roughly 10 - 20 knots of wind.

Sails very nicely - good performance into wind and very fast down wind. Lovely being able to reef the sails for the gusts.

The only issue I've found is that the sail isn't terribly beautiful when reefed - possibly need more/better luff parrels - currently only the lowest panel has one. It still works fine, just doesn't look as elegant as it should...

Sail is on the boat - very happy!

Still got a few things to sort out - notably fitting cleats for halyard, downhaul and throat haul. But it looks very nice!

Pic of sail on boat

Sail is now complete - pic is here: http://junkrigassociation.org/resources/MemberAlbums/29417059/Owl/IMAG0470.jpg

So far construction has been straightforward, following Arne's Method 2, although there were a lot of bits to sew together!

I've made it from 65gsm ripstop polyester which I think will be strong enough - certainly seems tough in the small panel size. The batten pockets are in acrylic canvas which I had left over from another project - basically because the colour contrast looks nice. The canvas is tied into the webbing at luff and leach so minimal loads are taken by the polyester. Yard and boom are in pockets too - we'll see how well that works...

Next step is get the battens and yard sorted, then get it all fitted to the mast...

Martin,

The actual centre of pressure, CP (or “dynamic CoE”) sits a bit forward of the Bermuda rig or flat JR  -  that is  -  if the max camber point is well forward in the sail. On a sloop JR that should be about 2-4% of the WL of the boat. On a dinghy, which usually has a big, efficient rudder, this is not critical.

I did slacken the sail of Johanna 10 cm (B=5.80m) along the battens to increase camber. That worked, but is also made the vertical curve rounder. On later boats I have tied the sail on moderately taut along the battens. This may result in slightly flatter sail than my chain calculator predicts, but the vertical curve gets more trapeze-like, as if the sail was made with the shelf foot method. In addition, there will be fewer wrinkles along the battens. The photo below, taken recently of Ingeborg’s sail, shows this: Look carefully on the shadows cast by the mast and lines onto the sail. I guess I prefer it that way, but I have no racing record, which proves this way is better than the slack Johanna sail.

I suggest you don’t worry too much. Making a fairly good junk sail is not rocket science. If the camber ends up at 6% instead of 8, or vice versa, you will not be in a crash-and-burn-situation.  Hurry up, the summer is gone before you know it!

Cheers, Arne

PS. I suggest you cut the battens about 2% longer than B. Then, after having sailed this season, you fit tape-marks to indicate how much you will shorten them before next season.

PPS: Yes, fit the battens flush with the leech.

Does camber on a junk sail pull the CoE forward from the PJR position? If so, do I need to compensate for this with the design of the sail (i.e. move the sail back or use a lower aspect ratio)?

Thanks