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Helpful Information:
Rigger’s Guide to proper swaging techniques

How to use Tension Gauges

Ahoy mateys

Hey today lets talk a little bit about the tension of your stays

I’ve got good news and bad news

The good news is Loos and Company helps take some of the guess work out of what the tension ought to be

Now they make three different tension gauges and it’s a function of how big your stays are, the size of your cable

So this is the middle one and there’s one for smaller cables and one for bigger cables

Now there’s certain tolerances that your stay should be within and that helps right here

They’ve got a little thing on here

The bad news is you’re not going to find a chart somewhere that says you have ABC boat and your stays are a quarter inch and you have such and such a sail, so your tension needs to be 900

While the tension on the stays is also a function of sailing performance, the shape of the sail

But you know there are certain tolerances that you should be within and Loos helps take the guesswork out of that

Now you may say to yourself well hey I’m not a professional rigger, what do I need this for?

All the more reason you need one of these

You know these professional riggers they can go around and they can test things out pretty well

Here you want to make sure that you’re somewhere in the tolerance levels of this and then fine-tune it as you get more comfortable and learn more about sailing

Especially racing sailors tension is very very important

Well let’s talk with Eddie the shop foreman here at the Salient Emporium who is a professional rigger to give us some general guidelines as to what we should be looking for and what we should have on our stays

And then he’s going to come on board my boat and we’re going to go through the process of how to use this gage and how to tighten the stays

Alright guys so here we are with Ed, a professional rigger, give us a little more information

Now Ed, as a typical cruising sailor how tight do I want my rigging to be?

You want it, you don’t want it tight tight but you do want it on the tight side because what you want to do is that so when you’re sailing if you’re on a starboard tack then the rigging on the port side is not loose

So you want everything to stay tight so say when the wind comes across starboard side pushing the sail and everything that way then if everything is too loose and all your rigging

you’ll see it on the port side will hang loose and vice versa if you want a port tack then all of the wind of the rigging on the starboard side will be loose

You don’t want to be able to see it moving around in the wind

So you want it to be a little bit tighter than looser?


Okay, now on this gauge here we’ve got now I’ve got quarter inch stays

I’ve already tested that guy’s

So here we’re going to go on anywhere from 450 pounds of tension to 2,000

Where do I wanna be at

I would start that somewhere about in the middle

So maybe somewhere around the 900 to 1100

Somewhere in that area at 11-13 percent

All right now is that for all the stays or just the two main ones that go up to the top

Well the uppers and the forward and the lowers will be tighter than your, the uppers your back stay head stay will be tighter than your lowers will be

Okay so we’re going to go out to the boat and see where I am

Now I did notice guys I took my main halyard and I brought it down

I measured on the starboard side and I brought it over to the port side and I seem to off a little bit there

You know so the mast is not quite straight

So I wanna straighten that out first

You want to get it to the center of the boat as far as side-to-side

You don’t want it more towards the starboard side, the top, or the port

You want to have it dead center of the boat

Okay now what stage are those the first ones we want  to do?

The uppers

We will start with uppers and get the masthead in the center of the boat as far as side-to-side

Okay, and then we’re gonna do the ones that go up to the spreaders?

Do the lowers yeah and that way once you get to the top of the mast in the center then you work down and you get the rest of the mast lined up with it

Okay, and so the tension is really a matter of the size of the cable?


And sail shape and kind of sailing you’re doing?


All right well guys let’s go out and just see how we do this, how we test this, and then how we actually adjust the turnbuckles to get the right tension

All right let’s go

Okay what we want to do is make sure the top of the masthead is in the center of the boat, side to side

So what we’ve done we’ve got a line hook here to the main hired and we’ll stretch it down to the top of the staunch and then go to the other side to see how they compare

You always want to make sure that whatever you use is it’s the same on both sides

That way you get a good accurate measurement

So we’ll pull it down and top of the staunch is right here so we’ll go to the other side of the boat and do the same thing and see how far off we are

All right so Eddie has given me this, let me see what we got here

You can see we are that far off so the mast, that top of the mast is actually heading towards the starboard side of the boat

So what we want to do is either loosen up on the starboard side and crank up on the port side, pull it over to get it straight

Or just crank up on the port of the rigging if it’s loose enough maybe we can pull it over and straight it out that way

And then once get it in the center then you take up evenly on both sides so that everything is tight

The same tightness on both sides and a mast stays on the center of the boat

Okay we’re going to check the tension now on this

We’re going to use the Loos gauge

Check tension on the upper

To use this we’ve added a safety feature here so we are gonna clip this around here so if we drop it, it doesn’t fall overboard

Okay then you just put the stays in between these two knobs here at the bottom

And you pull back on this and let it clip in there

And that’s where you get your reading from

You can see it’s on about 17 and then we look down this gauge here and 17 is up here

We need to be down in this area here somewhere

So that’s telling us we need to tighten up on this cord upper to get it one thing to get the mast over this way but also tighten up on the rig all together

All right yeah I’m pretty far off there Ed

All right now let’s look down at the turnbuckle and how do I actually do that

Okay once you get the locking nut loose

Not all boats have the locking nut sometimes they just have the stud coming down into the turnbuckle

And then there’s just cotter pins going through to hold it in place so if you have that you just pull those cotter pins out and then it’s ready to loosen or tighten

To tighten this we’re going to put the wrench on the flat spot of the fitting here coming down the rigging

And you can stick a screwdriver into the turnbuckle, the body turnbuckle, and turn it

Most time it’s counterclockwise to tighten so we will put a few turns on this and then check our tension gauge and see how much it changed

Okay so I’m tightening up on the turnbuckle and we’ll see how it changes on the gauge as I’m tightening up on this

Well this is pretty good Ed because we’ve got the gauge in place and as you’re tightening I can see it’s moving and we’re getting closer to, let me see what number we wanted

We wanted 32 and we’re at 25 right now so we’re getting there

Okay but now before we tighten up too far on this what we ought to do is check the top of the masthead again and see if we’re getting closer to pulling the mast back over to the side

we don’t want to go too far this way and then watch and loosen up on this side and pull it back on the other side

Okay so we want to take it in small increments?


All right well let’s test this and see here where we are on our straightening

Inside we are now here, we’ll take it over to the outside

Tail a little bit these gotta go to port just a little bit more but we’re getting real close

Actually right now we have gone too far to the port side

So when you tighten up on the starboard side and bring masthead back over this way a little bit

Alright so now we’re going to bring the gauge back over here and work on this one

Okay so you can see we’re right on 25 over here so we still need to get down into this area here around 30-32

So when we tighten that we bring that down, we’re also going to be tightening the other side too?

Yes we’re going to pull on the other side

So masthead back in the center and at the same time we’ll be tightening the rig both the uppers to get where it needs to get

Tightened it up on the starboard side now to bring the masthead back over this way and also tighten everything down to get it where it needs to be on the gauge

All right so now Ed we’re up to about 26-27

All right so now we’re on 30 here now we need to check for our straightness again?

Yes we’ll check straightness again and if we still want to make it tighter at that point if the mast in the middle then we want to take up the same on both sides

Take a turn here take a turn there or two turns here two turns there

It’s that way once it’s in the center we’ll keep it in the center

Okay so we’re kinda just gonna bounce back and forth?


Okay it’s pretty much right at the same height from each side to side so we got the mast pretty much in the center of the boat now

So then what we’ll do, we’ll work down from that

We’ll go down to the lowers and get the middle of the mast lined up with the top and the bottom

Okay we’ve got this set on 30 which is about midway of where I wanted to get it at

We’ll leave it there, we’ll get everything tightened and pinned and locked back in place and then we’ll start with the forward air flows get them tensioned and get the middle of the mast lined up with the top and the bottom

And you take it out sailing and check things out and then we’ll recheck it once you come back in

All right so now on these other ones that we’re going to do here

These things here ‘the half lowers and full lowers’ those need to be the same tension?

No they will not be as tight as the uppers are

they will be somewhere around the 20-26-28 somewhere in that range

Okay so we’re gonna do that next

All right Ed so now I got a pretty good idea of how this thing works and really it’s pretty neat

I don’t want to tie you up so I’ll go ahead and do the forward and half stays and can you come back and check me then?

Sure yeah I can check it, but just don’t forget when you get done, make sure all the turn buckles are locked back down so these nuts will screw down to the top and the bottom will screw up to the bottom

and then once you’re done that as an extra safety thing put in these caudal rings as it will go through the turnbuckle and in the holes and the studs there and that would keep those turnovers from backing out on their own

All right well I’m gonna give it a shot Ed

Man I tell you what, I’m just really shocked at how loose these stays were and how crooked my mast was

I’ma feel a lot better about heading out tomorrow

You’re sailing should be a lot better

Well thank you

All right Ed what do you think?

Well first thing I’m going to check is I want to make sure you got the mast in a straight column going all the way up and what I’m going to use is I’m gonna look at the sail track and if it’s off one way or the other here in the middle it’ll look like a snake or look like a banana

It would be bent so I’m just gonna look up the mast and see if it looks straight

Actually Dominic you’ve done a pretty good job as the mast track is straight all the way to the very top

Wow! All right

So the next thing we want to do probably is to check the tension on all the rigging to make sure everything’s at the proper tension

Okay and you’ve got that on actually pretty well, it’s up on 29

So you’re right in the area of where I wanted you to be

As long as this one’s the same and then what you want to do is just take this off of here and go over to the port side and make sure that everything is set to the proper tension on both sides

Which I would say they’re going to be because if not the mast when we pull it over to that side of the boat would not have been straight

And that you’ve got it exactly on 29 so that looks good

All right so I’m ready to be a professional rigger?

No, but you will be able to go out and adjust your sails and get it fine-tuned for you to sail the boat you know to what it’s supposed to be sailed at

I’ll get this cable out of the way here Eddie

Well Ed I really appreciate the help on this I think it’ll be helpful for a lot of cruisers

I’m headed out tomorrow so I’m gonna give it a test

Okay well good you definitely will see an improvement in the sailing I’m sure of that

Guys did you see how easy that was?

It didn’t take long at all and I’ll tell you what, I feel much better about going out sailing tomorrow, knowing that I’ve got even tension

I mean this thing was so far off it was unbelievable

This (Loos Tension gauge) I think is going to very very handy to have on board on a regular basis

Anyway guys happy and safe boating to you, your family, and friends

The Loos Tension Gauges take the guesswork out of cable or rod tension adjustment. The tension gauges are especially designed for accurate, repeatable tuning of a sailboat’s standing rigging.

(Cable Railing)

Sizes 1/8, 3/16, and 1/4

(Sail Rigging (Cable))

Sizes 3/32 to 3/8 and 2.5mm to 10mm

(Sail Rigging (Cable))

Sizes 3/32 to 9/32 and 2.5mm to 7mm

(Sail Rigging (Rod))

Sizes .172 to .375 and 4.4mm to 9.5mm

The Loos tension gauges take the guesswork out of cable or rod tension adjustment. The tension gauges are especially designed for accurate, repeatable tuning of a sailboat’s standing rigging.

Contrary to popular thought, a slack rig is more punishing on a hull than a properly adjusted, tight rig. Insufficient tension will not reduce the loads transmitted in the hull. Slack rigging will punish the spar and rigging needlessly by allowing excessive movement, chafe and shock loading. Modern fiberglass hulls should not be damaged by a properly adjusted, tight rig.

Figure 1 lists the rigging tension under different conditions for a typical boat with a properly tuned rig and with a slack rig. It will be noted that the maximum load is the same. However, for properly tuned rig the leeward / shrouds will not go slack under normal sailing conditions.

The lateral stiffness of the mast and the fore and aft stiffness of the spreaders is reduced by a factor of 2 when the leeward shrouds go slack. This Important structural characteristic is not generally recognized.

Rigging tension is becoming more important as a result of the trend toward the use of mast bend to control mainsail shape under different wind conditions. Mast bend will also affect the shape and trim of the jib, since mast adjustment generally affects forestay tension. The expert skipper will benefit by maintaining consistent rigging tension while developing the optimum sail shape and sailing tactics.

Sailboat Rig Tension Gauges
Figure 1

Safety and Performance


The failure of a fitting, shroud or stay could damage your boat, buckle the mast or even cause personal injury. To avoid such failure of (cable or rod) and fittings from fatigue or shock loading, it is important to set up your standing rigging with the proper tension. Too little tension in the shroud will permit the leeward shroud to go slack, only to fetch up with a jolt when the boat rolls or pitches. A less common problem is excessive tension. This can cause permanent stretch to the (cables or rods) and possibly damage the mast.


The actual set of sail under load is determined by the cut of the sail and the shape of the structure which supports the sail. Rigging tension plays an important part in determining the set of the sails.

When the boat has been tuned for peak performance, measure (cable or rod) tension should be recorded. The stainless steel used to make the rigging can stretch a little bit over time under high loading. Thus, marking turnbuckles, etc. cannot guarantee that subsequent adjustments will provide the desired tension. Only by gauging is it possible to repeat the initial tuning or improve it.

Limiting the sag of the forestay is perhaps the most important benefit to performance from having the proper rigging tension. Forestay sag permits the jib luff to fall off to leeward, tightening to leech and seriously degrading the performance to windward.

Tension in the upper and lower shrouds will influence the mast bend and set the mainsail. This is especially important on modern, fractional rigs where the mast bend is used to de-power the sail in heavy winds.

If the shrouds are not set up with enough tension, the leeward shrouds will go slack when the boat is sailing to windward. This can result in fore and aft pumping of the mast in a head sea. This mast movement will change the shape of the mainsail and can cause performance loss as well as possible structural damage.

Specific tension requirements for your application must be obtained from the boat, mast, or sail manufacturer or the manufacturer of the product on which the (cable or rod) is used.