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Flapping leach

Oct 30, 2017
153
Catalina c 27 Long Monday Lake Pueblo
we have had our Catalina 27 for about a year and a half now and have left the sails that were on her in place.

She came with a 150 Genoa and a 130... the 150 has been on the roller furling till this weekend.

Our spring winds here can be pretty gusty, plus the stitching at the crew of the 150 is needing some attention. So this weekend we switched out to the 130.

Then took her for a sail in 10-12 kts of wind. (Gust only to 17)
It was exactly what we were hoping for, evened out our heel but without the loss of performance.


Now the question.

The leach of the 130 was flapping pretty badly.
I assumed trim and moving the block (not sure I’m using the proper term here, the block where the Genoa sheet pulls through before the winch) further aft definitely helped.

We adjusted this position previously with the 150 for lighter or heavier winds but at no point did the leach of the 150 flap about.

Is the 130 old and stretched out? Is it just more sensitive to trim? What do you guys/gals think?


Oh it was the bottom third of the leach.

Thanks in advance.
 
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Likes: jssailem
Jun 8, 2004
2,270
Catalina 320 Dana Point
Should be a "leech line" to tighten just enough to stop flutter without "hooking" the leech.
 
Nov 9, 2012
2,435
Oday 192 Lake Nockamixon
The 130% sail has a shorter foot than the 150%. Therefore, the jib fairlead, the block on the track, should be moved forward to accommodate the shorter sail. Moving the fairlead forward will have more of a downward pull component on the leech, which will also reduce twist further up the sail. Moving a fairlead aft will have a greater pull component across the foot of the sail, allowing the bottom to be flattened and allowing the to twist off more.

This book, available here on the site, is a great place to start learning how to trim your sails better: https://shop.sailboatowners.com/prod.php?51998/Sail+Trim+Users+Guide

Some headsails do have a leech line, which pulls tight at the clew. However, having to pull too much leech line will "hook" the leech, making it curve to windward, which is slow and draggy. If proper fairlead positioning and leech line tension don't help your leech flutter, it's possible that your sail is stretched out. The Catalina 27 has been around a long time, last built in '91. If you don't know that your sails are new within, well, less than 10 years, then it's pretty likely they are stretched out.
 
Nov 8, 2010
10,586
Beneteau First 36.7 & 260 Minneapolis MN & Bayfield WI
The 130% sail has a shorter foot than the 150%. Therefore, the jib fairlead, the block on the track, should be moved forward to accommodate the shorter sail. Moving the fairlead forward will have more of a downward pull component on the leech, which will also reduce twist further up the sail. Moving a fairlead aft will have a greater pull component across the foot of the sail, allowing the bottom to be flattened and allowing the to twist off more.
This is not universally true. A 130 with a higher clew can have the same lead position as a lower cut 150. This is often done for this exact reason, like on a so-called 'Yankee' cut jib.

But yes in general, look for the car having to move forward as sail size drops.
 
Last edited:
Oct 30, 2017
153
Catalina c 27 Long Monday Lake Pueblo
I will look for the leech line.
As well as try moving the fair lead forward the next time we are out.

Btw, snow on the ride in to work this morning. It sure feels like winter does not want to let go.
Hopefully next weekend will be a little nicer weather than this last weekend.