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wsmurdoch 03-14-2015 02:53 PM

Riding Sail
 
Chris Parker forecasted 20 gusting 25 yesterday, so thought I'd try the riding sail here in Big Majors Spot in the Bahamas. I recorded the true and the apparent wind, both speed and direction. I also put a dynamometer on the anchor snubber to monitor the pull on the anchor. The riding sail was set on the backstay and sheeted to the port staysail lead block then back to a cabin top winch. The triangular sail is about 6'-6" along the backstay and 7'-6" on its foot. The water was almost calm in this protected spot.

Here are the recordings:

http://i602.photobucket.com/albums/t...nd%20Angle.png

http://i602.photobucket.com/albums/t...nd%20Angle.png

I put the riding sail up at about the 45 minute mark, had some trouble with the hoist until the 40 minute mark, then all was well.

The riding sail cut the swing in relation to the wind from +/- 30 degrees to +/- 15 degrees, and maybe half of that was due to the true wind variation.

The force on the anchor did not seem to change much, but I had to stand on the bow to read the dynamometer dial, and I quickly tired of doing that. The average force was perhaps 80 lbf and the maximum (the gauge has a tell tale) was 195 lbf.

Bill Murdoch
1988 PSC 34
Irish Eyes

CaptTony 03-14-2015 03:50 PM

Re: Riding Sail
 
Fascinating information. I take it things are a little slow where you are. : )

wsmurdoch 03-14-2015 05:57 PM

Re: Riding Sail
 
Quote:

Originally Posted by CaptTony (Post 2641962)
I take it things are a little slow where you are. : )

Actually, I've been quite busy today. Between long periods of taking in the view and resting, I swam down to look at the anchor, took a saltwater bath, read a little, had a beer... That sort of stuff. Right now I'm waiting for 5 o'clock to have a G&T.

Slow best describes the group that just flew in and out in a Cessna 208 (a ten seater) on floats. They taxied over to the beach and spent a half hour feeding the pigs. I'm from East Tennessee. If you go to that much trouble and expense just to feed pigs, you're really having a slow day.

Got to run.

Bill Murdoch

CaptTony 03-14-2015 05:58 PM

Re: Riding Sail
 
Darn. I wish I was that busy.

johnharch 03-14-2015 06:11 PM

Re: Riding Sail
 
Very interesting. It looks like your riding sail is fairly effective in dampening the swing. I've thought about rigging one, but never came up with a good plan. Can you give any more information about its construction and deployment? How is attached to the back stay? Does the foot run parallel with the deck? What material did you use for the sail cloth? What would you do to improve it?

When I anchor in 20 knots, I swing all over the place.

John
PSC 34, '91

Bene505 03-15-2015 12:06 AM

Re: Riding Sail
 
This past summer, I made a "block" part way up the backstay using a piece of rope and a knot similar to a prussic knot. The line that tightened it had a loop in it. I slid it up into position using 2 dock poles taped together for extra reach. I had it pre-strung with a halyard before doing so.

That setup worked really well. We have a cleat on the backstay 12" above head level, so that served to secure the halyard at the bottom. the halyard was tied into a big loop, so there was no way it could get unthreaded from the top loop.

When not in use, we kept the riding sail connected, but rolled-up and lashed to the backstay.

To raise, run the riding sail's "sheet" loosely to the winch on the mast. Un-lash the sail from the backstay. Loosen the halyard on the cleat, raise the halyard. Cleat firmly in place. Then tighten the "sheet" on the winch on the mast.

Regards,
Brad

wsmurdoch 03-15-2015 12:47 PM

Re: Riding Sail
 
Here is a photo.

http://i602.photobucket.com/albums/t...ing%20Sail.jpg

The sail is tacked to the stern rail with two short pieces of 3/8" line; one to the top of the stern rail to port and one to the outboard motor bracket on the rail to starboard. It is hoisted on the main halyard. The clew sheet is run forward to the staysail lead block then back to the port side cabin top winch. There are two jib hanks on the sail; one at the head and one at the tack. They are clipped to the backstay. Tacking the sail to the stern rail solves some interference problems with the HF antenna lead-in wire and its standoffs that run along the lower part of the backstay and takes some load off the backstay.

I bought the sail new from a Florida sailmaker on ebay. It was cheaper than I could buy the cloth. It is triple stitched zigzag, taped on all three edges, reinforced at all three corners, and with webbing loops at all three corners.

The real hero here is the software that does the graphing. It allows objective evaluation of the sail's performance. It's NavMonPC by Paul Elliott and Dirk Lison.

Bill Murdoch
1988 PSC 34
Irish Eyes

johnharch 03-15-2015 01:16 PM

Re: Riding Sail
 
Great, thanks Bill. The picture tells it all. Now I can add one more item to my ever expanding project list.

svHyLyte 03-15-2015 02:20 PM

Re: Riding Sail
 
For what it's worth, we have found the Banner Bay Fin Delta to be a great improvement over a traditional flat riding sail.

Group9 03-16-2015 10:07 AM

Re: Riding Sail
 
Quote:

Originally Posted by svHyLyte (Post 2643506)
For what it's worth, we have found the Banner Bay Fin Delta to be a great improvement over a traditional flat riding sail.

I've got one of those, too. But, I haven't got it out of the box yet. I'm looking forward to seeing how much it stops my boat from tacking at anchor.


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