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Old 27-08-2007, 00:44   #1
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Rig Tension

So here I am, sailing in the grand locale of Alaska, the other day we had the fortune to be running/deep reaching in to Seward, up Resurrection Bay in 12-18 knots of wind, glorious sailing. The boat is a Hutton 36, cutter, keel stepped, double in-line spreader, fairly raked mast, twin backstays, running backstays (used only when we fly the staysail or storm jib) and fore and aft baby stays. For all intents and purposes sailing here is mountain sailing, sudden and frequent wind shifts, we were on our toes. I grew up sailing in Colorado, so no big deal.

At one point we needed to jibe the boat, which was under 150 Genny alone. The jibe, even with perfect technique made the rig shudder more that I liked, which lead me to check the tension of the rig, which is newer than older, so still stretching. So in thinking about rig tension I poked around the Seward Marina and decided that it was definitly time to tighten things up as compared with other boats. The question is how tight? I am not a rigger, nor is there a rigger here to ask/hire. I am a smart guy, but do not have access to a tensioning gauge like I would use on a race boat. The rig is not out of tune, in so far as that the mast is strait as an arrow laterally, and has it's typical rake. I want to snug things down, have read the copious materials availible via Google, but I do not need to tune the rig, I need to tension the rig to take out the slack, to keep the rig from coming down.

So I am querying the collective community for advice, resources and anecdotes on real world CRUISING rig tension.

Thanks for your help!
Michael
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Old 27-08-2007, 03:24   #2
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You may think you merely want to snug up your stays/shroudes, but, in actuality, you ARE tuning your rig. I recommend that you read som,e of the rig-tuning guides, available on the web.

As a general rule, when the rig is fully loaded up, the leeward shrouds should be beginning to appear to slacken, so they can be deflected by hand, but not swinging loose, and the mast should stay in column.

A stay that is too tight feels rigid. A stay that is too loose feels limp.

The windward shroud should not have any visible slack, when sailing in about 10 kts of wind. The leeward shrouds should never* “slap”, even beating in heavier winds.

Tack often and beat upwind to adjust the shroud tension. Adjust the leeward shrouds since they have the least amount of tension, keeping careful note on the number of turns you put on your turnbuckles (to be sure they are evenly tuned). Generally, tighten the rig for heavier winds, and loosen the rig for lighter winds.

* You might get some momentary moderate slap during extreme gusts.

Tension guages are not all that expensive:

Pictured right: LOOS PT2 (3/16", 7/32", 1/4" Wire Diameters) under $90 (retail)
Cableware PT Tension Gauge Page

Pictured left: LOOS 90-B (3/16", 7/32", 1/4" and 9/32" Wire Diameters) under $40 (retail) Cableware 90 Series Tension Gauge Page

How to use Tension Gauges: How to use a Tension Gauge
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Old 27-08-2007, 03:25   #3
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I heard you crank them up till the toggles strip their threads and then back off half a turn.

Well that's what I always tend to do when i tighten anything....
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Old 27-08-2007, 03:35   #4
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Hi...I may be wrong but I believe that the windward shrouds and lee should not have slack in them at any time. This is because the loadings of a "snap back" as it shifts from one to the other is far greater than the tension load to prevent it happening. I cant see that it would be to hard to make a tension guage. You would need to have someone with a recently tensioned rig to calibrate it. I am sure that Gord has a picture of one sitting on his screen right now ; ) If not maybe local yacht club ?

cheers
Martin
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Old 27-08-2007, 05:00   #5
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My Selden manual explains how to tension shrouds with just a yardstick and a caliper which can measure millimeters. Of course you need to understand that as you tension one side of the rig, you are pulling it and tensioning the other to some extent.

I don't remember the exact procedure and I will get the manual and copy the information here, but the concept is as follows:

You hand tension the shrouds making sure the mast is plumb and the tape a meter stick to the shroud above the turnbuckle and mark a point on the shrould as a reference point. As you tension the shroud with the turnbuckle it is stretching and millimeter of stretch I believe is X% of the working load. The meter stick being taped to the shroud at the bottom is not changing length, but the reference point will move UP the shroud as it is tensioned and stretched. It needs to be about 3' for this approach to work.

This is a universal approach based on how much wire rope will stretch as percentage of its working load. I suspect that different forms of wire rope will vary 1x19, 7x19 dieform etc. My wire is 1x19, but too large diameter to use the standard tension gauges noted here.

I'll get the instructions and post them here.

When you are beating your lee shroud will go slack as the load on the rig stretches the windward one. If it is excessively loose...(over canvassed) for long periods having the windward shrouds stretched and loaded excessively, the movement of the lee shrouds CAN fatigue from the movement of the cable where it enters the terminal. This is where you might see failure as stands break at the terminal.

jef
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Old 27-08-2007, 05:26   #6
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OK found the manual online and I will try to attach the relevant pages:

jef
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The whole manual is useful:

Seldén Mast AB
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Old 27-08-2007, 05:48   #7
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Jef:
Thanks for the excellent find. I recommend that everyone download the:

Hints and advice on rigging and tuning of your Seldén mast
http://www.riggingandsails.com/pdf/selden-tuning.pdf

Includes:
Introduction, Rig types, Longitudinal rigging, Lateral rigging, Running rigging, Preparing the yacht for rigging, Checking the mast, At the crane, Keel-stepped masts, Alternative rigging of jib furling system, Tensioning the cap shrouds, “The folding rule method”, Tuning for safety, Masthead rigs, Fractional rigs, 19/20 rig and similar, Bergström-Ridder rig, Booms, Rodkicker, Working aloft, Unstepping the mast, Winter maintenance, Damage or cosmetic flaws?, Storage, Mounting new fittings, Masts which are seldom unstepped, Boat ashore with the rig still in place, Calculating mast and rig dimensions, Positive roach + in-mast furling, Sail slides and sail entry (MDS), The Seldén product range, Notes, & Conversion factors
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Old 27-08-2007, 05:58   #8
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Gord,

Let me thank you for your Manuals thread. This is a terrific resource. Hat Tip.

jef
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Old 27-08-2007, 18:49   #9
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Spot on as usual Gord........

cheers
Martin
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Old 27-08-2007, 19:53   #10
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What a great guide - Selden rocks...
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