Loos & Co. tension gauge

[Halifax Sailor]

Been looking for one, got lucky and got one for just a little money. It's a PT-2 model. NOW, i know it's important to have proper tension on the rigging. I am mostly a cruiser, 3/16 wire rigging. After reading the on-line instructions, still not sure how tight or how much tension to put on my rig. Can anyone explain exactly what i should be doing? have always just tightened to make the mast straight, then watched the rig when sailing to ensure it didn't bag too much one side or the other. not scientific but now i have the tension gauge. just looking for some advice.

[Matt Johnson]

Typically 15% of break strength for cap and uppers, lowers are a bit lower tension. I have very little data left on my tablet so can't look up strength of 1x19 3/16" for you.

The way you did it in the past is a good without specific info from the manufacturer.


Matt

Sent from my LG-V410 using Cruisers Sailing Forum mobile app

[thomm225]

On my boat, I set all stays to 440 except the forward lowers which I set at 550 for a bit of prebend.

That was 3-4 years ago and my mast is still at the same angle

But if I had it to do over, I might go a bit easier on the tension since my boat is 40 years old. I was used to racing and my boats were practically new.

Some say you can harm an old boat cranking in too much tension.

How old is your boat?

[Halifax Sailor]

my boat is 1980 Mirage built in Montreal. built in the days when fiberglass was cheap and they built them thick. some cracks on the surface but no stress fractures anywhere and i have crawled pretty much thru the boat. all have backing plates, new forestay last year, dont know age of other rigging, all wire though.

[dagranger]

You can go to web sites of sailmakers and use their resources for some of the similar boats..The best way is to sail the boat and look at the rig to make sure of its straight up and down no bends unless the mast is designed to bend you really are better off straight up and down..headstay not to sag off too much as this will affect your upwind sailing ability..there is no need to make stays tighter than is necessary to keep everything up and down..too tight will put undue loads on mast step I currently have a santana 20 I race and you might find the sailmakers website on tuning very helpful there is not one set it and forget it. If you want it right..Don Friday Harbor

[reed1v]

For cruising we always kept stays and shrouds loose enough so you could pull them one inch out of true. You want all your rigging to have some play and enough toggles so the rigging can bend in all directions as the stresses change. Never start tightening leeward shrouds when under sail. they are suppose to be loose. Rule of thumb is tighten your turnbuckles hand tight and then half turn with your fid.

[Mikado]

Originally Posted by Halifax Sailor

Been looking for one, got lucky and got one for just a little money. It's a PT-2 model. NOW, i know it's important to have proper tension on the rigging. I am mostly a cruiser, 3/16 wire rigging. After reading the on-line instructions, still not sure how tight or how much tension to put on my rig. Can anyone explain exactly what i should be doing? have always just tightened to make the mast straight, then watched the rig when sailing to ensure it didn't bag too much one side or the other. not scientific but now i have the tension gauge. just looking for some advice.

I just finished adjusting all my rigging with a Loos & Co PT-3. What a great tool to have on board, simple yet effective.

I was facing the same question that you are. I have never adjusted my own rigging but felt this is a skill that I should have. Although my wire is bigger in diameter, same principal should apply. I purchased a book on rigging but it was more focused on rigging a boat from scratch and found it too technical for me. I found this tutorial on line that contained just the information that I was looking for.

http://www.seldenmast.com/files/1416.../595-540-E.pdf

I first started by looking up he breaking load of each wire diameter. I read that rule of thumb is when tensioned the wire should not exceed 15% of the breaking load. My static loads don't even come close to that but I'll check while sailing under various loads to help educate myself. Next I checked some of my neighbors rigging, starting with someone who just had their rigging replaced professionally. The others were boats that sailed regularly. By researching on-line, I determined how my masts should look static. Here's the tensions that I ended up with to use as a baseline. On my next sea trial I will pay close attention to how the masts look under sail and might adjust a little again, but you have to start somewhere.

5/16" = 25-27 lbs
3/8" = 36-37 lbs
7/16 = 51 lbs

I also paid close attention to my spreader angles. I read 6 degrees was the correct angle. Looking around the marina at other boats they were all over the map, some angled down, some flat, and some closer to 20 deg than 6.

A rigger that was working on my neighbors boat came by and looked at the masts then felt the wire tensions by hand and said it all looked reasonable to him.

I used one of the diagrams in the Selden Mast booklet to document all my settings for future reference.

Please keep in mind that this data is what I came up with and in no way is intended to be used other than a point of reference. As I said I am a complete novice but hope to become proficient at rigging adjustment over time.

Good luck,

Jeff

[thomm225]

Quick Loos Gauge guide on breaking strength for normal size rigging and some settings.

How to use PT Series Tension Gauges

[thomm225]

Quick ref breaking strength

The same principles apply for other wire sizes:
WIRE SPECIFICATIONS for 1 x 19 Stainless Steel Rigging Wire:
Diameter - Approximate Breaking Strength
1/8" - 2,100 #
3/16" - 4,700 #
1/4" - 8,200 #
5/16" - 12,500 #
3/8" - 17,500 #
7/16" - 23,400 #
½" - 29,700 #

[reed1v]

Spreader angles should be equal on each side, ideally. In other words, the angle the spreader makes with the upper portion of the shroud should be equal to the angle it makes with the lower portion of the shroud as measured at the point of contact with the spreader. Thus spreaders should be angled upwards, unless you got an inboard rig rather than at the toerail or outboard. That keeps the compression equal on both sides.

BTW, make sure you do not attach in a fixed fashion the shrouds to the spreaders. Ideally they should just run though the groove. If the spreader wants to walk down the shroud, then a stopper under the spreader attached to the shroud will prevent that.

[jag39]

Don't leave them loose. You should still have tension on the leeward shroud when it is the "slack non-loaded" shroud. If it has slack when you tack or gybe, you could break something. I always put 200-300 lbs on mine, more on the headstay and backstay. Or, pick the middle area on the scale for your size rigging. Can't go too wrong with that. Just an opinion, though, and I'm not a professional rigger.

[reed1v]

That is the wrong way to do it, but if your happy with it, so be it. For deck stepped masts, that will eventually compromise the deck and possibly the compression post. For keel stepped masts, that will eventually transfer the excess compression to whatever the chainplates are attached to.

[Mithril Bham]

Originally Posted by Mikado

I just finished adjusting all my rigging with a Loos & Co PT-3. What a great tool to have on board, simple yet effective.

I was facing the same question that you are. I have never adjusted my own rigging but felt this is a skill that I should have. Although my wire is bigger in diameter, same principal should apply. I purchased a book on rigging but it was more focused on rigging a boat from scratch and found it too technical for me. I found this tutorial on line that contained just the information that I was looking for.

http://www.seldenmast.com/files/1416.../595-540-E.pdf

I first started by looking up he breaking load of each wire diameter. I read that rule of thumb is when tensioned the wire should not exceed 15% of the breaking load. My static loads don't even come close to that but I'll check while sailing under various loads to help educate myself. Next I checked some of my neighbors rigging, starting with someone who just had their rigging replaced professionally. The others were boats that sailed regularly. By researching on-line, I determined how my masts should look static. Here's the tensions that I ended up with to use as a baseline. On my next sea trial I will pay close attention to how the masts look under sail and might adjust a little again, but you have to start somewhere.

5/16" = 25-27 lbs
3/8" = 36-37 lbs
7/16 = 51 lbs

I also paid close attention to my spreader angles. I read 6 degrees was the correct angle. Looking around the marina at other boats they were all over the map, some angled down, some flat, and some closer to 20 deg than 6.

A rigger that was working on my neighbors boat came by and looked at the masts then felt the wire tensions by hand and said it all looked reasonable to him.

I used one of the diagrams in the Selden Mast booklet to document all my settings for future reference.

Please keep in mind that this data is what I came up with and in no way is intended to be used other than a point of reference. As I said I am a complete novice but hope to become proficient at rigging adjustment over time.

Good luck,

Jeff

Thanks for the Seldon link. Very good.

[Dennis.G]

Originally Posted by reed1v

For cruising we always kept stays and shrouds loose enough so you could pull them one inch out of true. You want all your rigging to have some play and enough toggles so the rigging can bend in all directions as the stresses change. Never start tightening leeward shrouds when under sail. they are suppose to be loose. Rule of thumb is tighten your turnbuckles hand tight and then half turn with your fid.

I would caution against this advice as you can easily end up with a rig that is too loose. Checking leeward shrouds for any slack when sailing is actually a recommended tuning procedure. In normal sailing conditions (say strong enough to heel the boat over 15 or 20 degrees) you should have zero slack in the leeward shrouds. A loose rig like that is in danger of very high shock loads when loads suddenly removed. Much better to have a higher static tension on the rig than subject the rig to shock loads from shrouds being too loose. I am not sure where the "hand tight then half turn" rule of thumb came from, but I don't trust that thumb. (well, I guess I ran my Hobie cat that way, but not a cruising sailboat).

Check with a professional rigger or maybe read "The Complete Riggers Apprentice" for reliable advice. 10% (lowers) to 15% (uppers) of breaking strength of wire is normal range of rig tensioning and is easily read from a Loos gage.

[Neptune's Gear]

I 2nd the you should not have slack leeward shrouds. A very good reference is "sail and rig tuning" by ivar dedekam. Really easy to understand, even for a beginner. I keep a copy on board as a reference, and it is very well worn (I loan it to others). Great book at a reasonable cost. Google the name and or Author, and you will find lots of sources.
The loos gauge is great.