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Monday, February 29, 2016

A picture is worth a thousand words...when tuning sails!

I've built two RG-65's; both Blue Splash designs. The first, Peck, is a trial horse of sorts, and has raced reasonably well in past competitions. It belongs now to my son Andrew. Now, I've completed my own boat, the Mustang, and I'm getting it worked up to form.

I took the Mustang sailing this weekend, and except for turning it on and putting the drain plug in, sailed remarkably poorly. Of note, some geometry errors in the sheeting system led to binding so that the swing rig had quite of bit of trouble getting out in wing-on-on scenarios...I think I have that fixed now. Also, the rig was wildly out of tune; to wit, see below:

I see a few things wrong here on the starboard tack; first the luff curve of the jib is dumping air into the leach of the main causing some back-winding. You can see the disturbed air "ruffling" in the main just below the second panel seam near the mast down to the national identifier. The jib geometry looks wrong; the head of the jib looks to far to starboard, and the slot looks to wide, probably why I was usually first to tack in the shifts as my jib fluttered before everyone else's. Lastly, while not visible here, the jib itself is high, I need to lower the jib boom in relation to the swing-rig fore strut. Maybe too much jib luff too...what do you see?

Anyhow, I made some adjustments, and went out again on the next day to test the new running rigging and trim; as seen here:

Here, the main looks pretty good, powered-up with a nice curve, and smooth without any sign of back-winding. Note the head of the sail is not twisted-off, to give some power in the light air. The jib geometry looks a bit better, and the slot has been closed up some...but I wonder if it is to far forward of the mast? Also, here you can see. Jib is still high and needs to come closer to the deck. It seemed to sail better, so I am making progress...what do you see? Feel free to post your comments!

As an aside, the swing rig really does get you moving in light air as the video below shows...what do you think of the sail shapes?

Sometimes you just get lucky; after some late afternoon testing, the sun beautifully illuminated the sails on the way home...

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