Standing rigging tension?

Bob_S

.
Aug 23, 2020
19
Oday 28 Branford
Hello all and thanks in advance for any help / suggestions. I'm setting up the standing rigging on my '83 Oday28. Using the Loos Tension Guage. All shrouds are 7/32nds - The Loos guages give readings that translate into percentage of breaking strength. Does anyone have a good idea of what percentage would be "right" Right now, although not all the same they're tensioned to about 10% of breaking strength +/-.
Thanks again an Fair Winds
Bob S...

Oday 28 - Kiltimagh
 
Jan 7, 2011
4,727
Oday 322 East Chicago, IN
Great question…I borrowed a neighbors Loos gauge and check my shrouds and stays…mine are 1/4”…

The Loos gauge says mine are about 30% of breaking strength…but what is the target/ideal %?

Is it boat-specific? I don’t see any references in my O’Day 322 owners manual.

Greg
 
Jan 4, 2010
1,037
Farr 30 San Francisco
When in doubt tighten it until something goes bang and then back it off a quarter turn. Find a manual or consult a rigger mistakes can be expensive.
 
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Likes: sail sfbay
Jan 7, 2011
4,727
Oday 322 East Chicago, IN
I found these charts from Loos…

I may be reading a reading of “30” as% when it is something else…

.

I am going to remeasure and refer to these charts…

Greg
 
Oct 26, 2008
6,045
Catalina 320 Barnegat, NJ
30% seems very excessive to me. I used the Loos gauge to start my shrouds at 15% on our Starwind 27 masthead rig and that was quite a bit tighter than the rigger set them. It also caused some very slight friction on the bottom of a door directly under the mast. I backed off from 15% down to about 12% to remove the friction. There were no other visible signs of strain. I would be very careful about going higher than 15%. At about 12% there was no slack at all in the leeward shrouds, even in a decent wind. I only measured the shrouds because the forestay had furling (you can only measure tension at the backstay) and I regularly used a backstay adjuster, so a measurement of the slack setting was basically not important.
 
Jan 7, 2011
4,727
Oday 322 East Chicago, IN
30% seems very excessive to me. I used the Loos gauge to start my shrouds at 15% on our Starwind 27 masthead rig and that was quite a bit tighter than the rigger set them. It also caused some very slight friction on the bottom of a door directly under the mast. I backed off from 15% down to about 12% to remove the friction. There were no other visible signs of strain. I would be very careful about going higher than 15%. At about 12% there was no slack at all in the leeward shrouds, even in a decent wind. I only measured the shrouds because the forestay had furling (you can only measure tension at the backstay) and I regularly used a backstay adjuster, so a measurement of the slack setting was basically not important.
Yes Scott,

As I noted on my second post, I read the “30” on the Loos gauge as %…but it is not…

I built this little chart to use when I go out to the boat next, to check my tension on the gauge, and to have an idea what it “should” be…or at least close to it..
54ADA403-FF0F-4068-BEB9-DEEB3496FCE6.png



30% of breaking strength is a bit high I think for a regular old boat.

Greg
 
  • Helpful
Likes: Ward H
Jan 1, 2006
7,040
Slickcraft 26 Sailfish
It was or is my impression that 20% is center. But, maybe that's not right. In any event, if you tune the rig very tight you can end up bending the boat. You can sorta see that with the Loos gage because at some point the tightening of the wire tensions by turning turn buckles doesn't produce a corresponding increase in wire tension on the Loos gage. That's because the boat is bending.
I had a Mark 25, which no one has heard of because there were only 15 built. It was a 25' C&C with a franctionly rigged 40' spindly mast with jumper struts to stiffen the upper mast sections. In short the first seasons I sailed the boat, I worried about the rig holding up. After that I worried about the hull standing up to the rig.
You can tighten all you want, but unless your boat was designed for that, it does no good.
 
Jan 7, 2011
4,727
Oday 322 East Chicago, IN
My only reason for checking mine is that my leeward shrouds get pretty loose when sailing in a brisk (20+ knots) wind.

My head sail furler also seems to have a sag (135 genny) in a strong wind.

So I don’t think that I am tuned too tight, but probably a little on the loose side.

But yes, you can certainly do damage over tightening the shrouds and stays.

Gteg
 
Jan 1, 2006
7,040
Slickcraft 26 Sailfish
We had a guy in our Club level fleet with a Pearson - maybe a 33. He loved to crank up his backstay going upwind. He wanted so badly to get that sag out. After two dismasting the boat yard that did the previous two replacement refused to give him an adjustable backstay.