Loos Gauge for Standing Rigging

Jackdaw · Sep 10, 2014

Only the CR models are designed for 304SS. The 'regular' models are for 316 marine stainless. 304 is stronger, so the gauge reading will be off.

Jackdaw · Sep 10, 2014

Paul and Judy said:
Jackdaw - what do you mean by CR models vs regular models.

The 'standard' LOOS gauge is designed for marine rigging and 316SS

http://www.loosnaples.com/tension-gauges/professional-models

The CR version is for architectural rigging and 304SS

http://www.loosnaples.com/tension-gauges/professional-model-pt-cr

Jackdaw · Sep 10, 2014

Paul and Judy said:
I do not see where they specify 316. Can you point me in the right direction, please

Professional Models - Higher accuracy and easier to use than standard models. The cable can be adjusted while the gauge remains on the cable. "Just watch the pointer move." All readings are based on 302/304 1x19 S.S breaking strengths.

Interesting.... I always assumed that the CR was 304 based, and the marine ones were 316. That bothered me.

So I called Loos and talked to their VP of Engineering. He said while the actual TENSION of the rig will be a few % lower then the number shown (due to the strength of 316 vs 304), the PERCENT of the breaking strength will be right on.

As we set rigging to % of breaking strength, its all good.

Claude L.-Auger · Sep 10, 2014

Jackdaw said:
Interesting.... I always assumed that the CR was 304 based, and the marine ones were 316. That bothered me.

So I called Loos and talked to their VP of Engineering. He said while the actual TENSION of the rig will be a few % lower then the number shown (due to the strength of 316 vs 304), the PERCENT of the breaking strength will be right on.

As we set rigging to % of breaking strength, its all good.

FWIW the Loos models A & B are also based on 302/304 so I'm guessing the same rule as quoted by the VP would apply?

Jackdaw · Sep 11, 2014

Claude L.-Auger said:
FWIW the Loos models A & B are also based on 302/304 so I'm guessing the same rule as quoted by the VP would apply?

Yes sir.

Claude L.-Auger · Sep 11, 2014

Jackdaw said:
Yes sir.

Thanks

John23883 · Sep 12, 2014

20% !!

Did Hunter say to set AT 20% or not to exceed 20% of breaking strength?

To put it in perspective, on my Hunter 26, 20% of 3/16 wire would around 940 pounds. Let's think about that for a second; I'm going to stack (12) 80 lb bags of Sakcrete at the mast base to equal 940 lbs. If you have 1/4 wire that would be 1460 lbs or over 18 bags high.

I am at 600 lbs on the upper shrouds, 400 or so on the lowers (to set correct mast bend) and they sound like a piano string when tapped.

I was asking the same question as you; How much tension? No one will say officially!

The 600 lbs I use came from an expert on rigging who said 20% was a bad idea.

gray125 · Sep 12, 2014

This book is the reference that I use: http://www.riggingandsails.com/pdf/selden-tuning.pdf It recommends that the uppers be set at 15 to 20 percent of breaking. If you add up the tension in each stay, it's a lot of tension. I don't race so there's no way I would set it to 20%.

IMHO: The rig should be set as tight as it needs to be and no tighter. I set the rig tension while sailing, making sure the lee side has no slop in at least 15 knot winds under full sail. To make sure I haven't over tensioned the rig and that uppers and lowers are not out balance, I measure at the dock with a loos gauge, but just strumming them and listening to the pitch of the sound you can get them pretty close. In my case the uppers came out to be about 13% breaking strength. A little under the recommended 15%-20%.

Jackdaw · Sep 12, 2014

gray125 said:
This book is the reference that I use: http://www.riggingandsails.com/pdf/selden-tuning.pdf It recommends that the uppers be set at 15 to 20 percent of breaking. If you add up the tension in each stay, it's a lot of tension. I don't race so there's no way I would set it to 20%.

One thing to remember.... because the stays are 'coupled' system, the tension added to one is split with the other. On other words, turning either turnbuckle add tension to both stays and the static tension is always equal. Your only other goal is keeping the mast straight.

The thing to remember about that point is that's only true statically. Once the rig loads up and the lee side goes slack, the tension on the windward side grows to make up for the slack.

gray125 · Sep 12, 2014

Jackdaw, I'm not an engineer so I'm not sure I understand what you wrote. I understand that if I tighten the left side the right side also get tighter, but what I was saying is the all of the downward tension in the stays add and are opposed by the mast and mast step. Is that not correct, that to find the compression in mast I have to add all the downward tension in the stays?

Jackdaw · Sep 12, 2014

gray125 said:
Jackdaw, I'm not an engineer so I'm not sure I understand what you wrote. I understand that if I tighten the left side the right side also get tighter, but what I was saying is the all of the downward tension in the stays add and are opposed by the mast and mast step. Is that not correct, that to find the compression in mast I have to add all the downward tension in the stays?

That's correct. I was just talking about tension in the rig. But I would not worry about mast compression.... that's a column load and all boats should be able to handle many times more compression load then tension in the rigging.