Rigging tension gauge

jonathankent

jonathankent

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I have seen these in the various chandlers for about 30-40 quid, but just how do they work and how do you use them for tensioning the rig. The descriptions are nearing awful and the picture doesn't help whatsoever.... so your assistance is much appreciated.
 
Sorry had to get this in but I've got a spare as new Loos type B to sell for £25 inc postage, it's for 5,6,7 mm wire.

The basic idea is you try to deflect the wire a set amount using two points of contact and measure the force required to do that. The tighter the wire the more force required to deflect a set amount or the less deflection there is for a set force.

The read value is looked up in a table attached in the gauge and there is a choice of tension vaues for each size of wire.

I reckon the Loos type gauges are only accurate to about 15% but it does give a reliable way of comparing rig tensions before and after port and starboard etc.
 
Mine is only 3mm wire, so unfortunately yours wouldn't help me to save a few quid....

Has anybody noticed a difference after using one of these gauges as supposed to doing it by eye and a bit of pulling/swinging on the rig??
 
Its not a racing yacht is it?
Go for a sail in a F3 The lee rigging should just start to go slack at 15 to 20 degrees of heel. Tighten both sides equally as necessary. If it does not go slack at 20 degrees it is too tight.

But what is the rig. Masthead, fractional, swept back spreaders???
 
... fractional & swept back spreaders...

Ita not a racing yacht, but would obviously like to get the best out of it.... when I only get 3-4kts that little extra could make a bit of a difference....
 
[ QUOTE ]
Its not a racing yacht is it?
Go for a sail in a F3 The lee rigging should just start to go slack at 15 to 20 degrees of heel. Tighten both sides equally as necessary. If it does not go slack at 20 degrees it is too tight.

But what is the rig. Masthead, fractional, swept back spreaders???

[/ QUOTE ]With the greatest respect, Vic, some rigs should NEVER go slack on the leeward side. There will be less tension on the leeward side as the boat heels, but the wire (on some fractional rigs for instance) should never be slack or you will risk losing the mast. I am only concerned that some people read these forums and might believe that such advice is generic or all boats.
 
I was told recently that a 3mm extension in 2000mm produces a load of 15% of breaking strain for any size of wire used in yachts. i.e. measure and mark accurately 2000mm on the wire when slack and then tighten until it measures 2003mm.

I haven't got technical and done the sums yet but has anyone else heard of this?

A friend reckons a rigger told him to try and acheive this as a "working load" for the caps on his fractional rig.

I check for sloppy lee shrouds and adjust when in harbour.

Cheers
 
[ QUOTE ]
I was told recently that a 3mm extension in 2000mm produces a load of 15% of breaking strain for any size of wire used in yachts. i.e. measure and mark accurately 2000mm on the wire when slack and then tighten until it measures 2003mm.

[/ QUOTE ]

Yes thats right the method is described in the Selden masts Hints and advice manual refered to by capt courageous.
 
[ QUOTE ]
I was told recently that a 3mm extension in 2000mm produces a load of 15% of breaking strain for any size of wire used in yachts. i.e. measure and mark accurately 2000mm on the wire when slack and then tighten until it measures 2003mm.

I haven't got technical and done the sums yet but has anyone else heard of this?

A friend reckons a rigger told him to try and acheive this as a "working load" for the caps on his fractional rig.

I check for sloppy lee shrouds and adjust when in harbour.

Cheers

[/ QUOTE ]Not sure what you mean by 'working load'. I have used the method when setting a fractional rig up from static. The load will increase when the boat is hard on the wind. The 3mm extension over 2000mm is a good technique and I believe is the one that others are referring to in the Selden down-loadable handbook.

On older boats, it was easy to overstress the hull and rig by tightening up the leeward shrouds when the boat was heeling. Some older (mainly wooden) boats were not designed for the sort of pressures that tightening the rig in this way can exert.

This does not NECESSARILY apply to modern boats. Rigs and tensions are much more accurately calculated nowadays. Hence the complete nonsense that is sometimes written about oversize rigging putting too much stress on the boat. Provided that it is tensioned correctly, the stress on the hull is exactly the same at any given angle of heel, regardless of the size of the rigging.
 
[ QUOTE ]
some rigs should NEVER go slack on the leeward side

[/ QUOTE ] The response was to a question about a Fantasie 19 although at the time I had not quessed that it would have a fractional rig. The pictures I have found all seem to have mast head rigs.

The only sound advice would come from the builder or the mast manufacturer or a professional rigger. The builder is almost certainly no longer around and there was probably no advice given with the boat when it was new anyway. The chances are that the mast manufacturer is not around now either unless the boat has been re-rigged with a mast from a manufacturer who is. It is hardly worth taking a boat like this to a professional rigger!

Fractional rigs with aft swept spreaders are difficult to tune as he will find if he reads the Selden manual.

He will probably find as I have done with a similar sized boat (but mine has a masthead rig, aft swept spreaders and lowers in line with the mast) that at the end of the day he just has to experiment and settle for something that looks and feels correct not only in terms of tension but in terms of mast rake as well.

I think one fact he will glean from the Seden maual is that the tension sould not exceed 25% of the breaking strain which is equivalent to an extension of 5mm per 2m length.
 
[ QUOTE ]
Hence the complete nonsense that is sometimes written about oversize rigging putting too much stress on the boat. Provided that it is tensioned correctly, the stress on the hull is exactly the same at any given angle of heel, regardless of the size of the rigging.

[/ QUOTE ]

The problem arises when a boat is rigged with heavier wire and that is tensioned to say 15% of its breaking strain, maybe by using the stretch per 2000mm method. You are correct provided the heavier rigging is only tensioned to the original figure in kilo Newtons.
 
Another thought:

The Fantasie 19 is a Tucker design based on one of the Silhouettes.

If you go the the Silhouette owners association website you will find a forum wherein, if you search for Fantasie, you will find a number of threads some of which relate to rigging. I have not read through it all but there may be some useful info there or it may be you will find some contacts who will be able to give specific advice.
 
[ QUOTE ]
Hence the complete nonsense that is sometimes written about oversize rigging putting too much stress on the boat. Provided that it is tensioned correctly, the stress on the hull is exactly the same at any given angle of heel, regardless of the size of the rigging.

[/ QUOTE ]

Must disagree John - when people increase wire sizes, they do add additional strain - eg 4mm wire with a min BS of 960kg will be seeing 144kg load at the 3mm / 2000mm example from the Selden site, whereas 5mm wire will be seeing 225 kg load at the same stretch, therefore the hull is seeing a load increase of greater than 64%. The 5mm wire tensioned to 144 kg would be inadequately preloaded (at around 9.5% stretch) and in danger of shock loading the wire, as well as causing the leeward shrouds to seem very slack when sailing to windward.
 
[ QUOTE ]
[ QUOTE ]
Hence the complete nonsense that is sometimes written about oversize rigging putting too much stress on the boat. Provided that it is tensioned correctly, the stress on the hull is exactly the same at any given angle of heel, regardless of the size of the rigging.

[/ QUOTE ]

Must disagree John - when people increase wire sizes, they do add additional strain - eg 4mm wire with a min BS of 960kg will be seeing 144kg load at the 3mm / 2000mm example from the Selden site, whereas 5mm wire will be seeing 225 kg load at the same stretch, therefore the hull is seeing a load increase of greater than 64%. The 5mm wire tensioned to 144 kg would be inadequately preloaded (at around 9.5% stretch) and in danger of shock loading the wire, as well as causing the leeward shrouds to seem very slack when sailing to windward.

[/ QUOTE ]You aren't disagreeing - you are agreeing with my proviso, 'Provided that it is tensioned correctly...'

Of course if people wish to wind up their rigging to more than the designed tension they will put excessive tension on their hull. If they put bigger wire on, they will find themselves able to put even more tension on their hull. However the reality is that very few people have anywhere near enough tenison in their rigging, and rigging size 'in itself' does not add to load on the boat.

Use a tension meter might be one answer, or if you are using the method of measuring the stretch over 2000mm to measure tension - make sure you have the correct rigging size on your boat!
 
Re: Rigging tension gauge... Rick ...

Your argument is based on setting the rigging to the same tension as shown by extension of the rigging ....

If the rigging is set-up by actual load on rigging / deck fittings - then there is no difference 10mm or 3mm diam wire.

The problem is that there is no real way other than spring load meter between stay and deck fitting to gauage that - so what is used is either extension of stay - the 3mm in 2mtr trick - or the deflection of stay from natural line ... the clip on pull plate meter. Both of these systems fall apart when rigging is not the size designed for the boat.

A number of boats doing ARC etc. go up one size in rigging stays - this is not a bad idea - as a boat should be designed at such safe margins in this area - that the increase of load of one size up in rigging shouldn't cause problems.....

One cause for concern though when rigging boats and setting the tensions / loads ... coachroof depression - gets worse as boar gets older - or even I've seen new / near new boats that depress alarmingly at correct setting ... and of course keel-step. With Keel step alarming damage can be done to a boat when overstressed on that point ... and normally that damage cannot be seen or detected until too late ! Unless a "halyard check" be done at intervals through boats life.

What you do is step mast and leave rig slack enough that measurement of deck to mast-top is "natural". Do this by using a halyard - reason for name ! Now tension up mast stays till normal setting ... now re-measure ... There will be a difference as mast pushes keel and deck apart .... Make a note of this figure. Now take halyard and measure to a fixed point fwd, aft, port and starboard ... make a note of all these figures AND which halyard used !!

Now when re-stepping mast later - you can either - do the measure tension all round and set stays etc. - or use above figure to set overall tension of rig and then a halyard to fwd, aft, port, starboard to check mast is vertical / set as should be by comparing measurements. Simple init really !!
 
Re: Rigging tension gauge... Rick ...

FWIW. I made my own, using a friends DIY one as a template. It is just an approx 500mm long piece of aluminium with two sheaves on one end and a hole and a spring gauge in the other. You run the wire between the sheaves and hook the spring gauge on the wire. The reading is relative naturally, but very repeatable. I set mine so that it shows 3,5-4Kg and that was based on the same tension on the one I used as template. At that point the side and aft stays go slightly slask when tacking in stroge winds.

That Selden PDF looks promising. Must print it and read.

My boat is 24ft and has a masthead rig with double lower stays.
 
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