Tension on standing rigging

[mickmeck]

The tension on many of my shrouds is very lose. I have the tool to measure what it is but don't know what it should be. Is there anyone who would know what the tension should be for a 2003 Jeanneau 43 DS? 

[MartyB]

Assuming you have a Loos Guage, generally speaking 15% of breaking strength in tightness is what you want. Possibly upwards of 20%.

I had a full bore how to put out by Ullman at one time in a word doc that is very good on how to adjust the rig.

Generally speaking, get the mast straight up and down inititally side to side, fore to aft. With a bit to aft, ie a degree or two is what you want. Then start at top shrouds adjust ea to 10%, go next ones lower, then again if a double or triple spreader rig. Also make sure the spreaders are level or slightly up in direction. Ea side equa distance from the deck.

Adjust fore and back stay to 10%,

repeat at 15%. Making sure the spreaders and mast do not go out of allignment.

This is a real simple explanation.

If you know the mast maker, many of them have an online adjustment guide. Seldon has one, or has in the past.

Marty

[mickmeck]

Thanks MartyB. I will tune it to 15% as per your recommendation and look for more details over the winter. 

MickMeck

[so40gtb]

The Selden mast rig tension article is very helpful, probably one of the best.

On our SO40 and our prior SO34, one could not easily determine the forestay tension. I've been setting the backstay tension at 16% of breaking strength (8% on each of the two splits of the backstay), which should put a higher tension on the forestay. At one point, I created a vector analysis spreadsheet that calculated the forestay tension based on all the other tensions, but I don't think that degree of rigor is necessary (and I've not been able to find that file recently).

I tensioned the shrouds in accordance with the Selden recommendation, though Voyaguer has a Z Spars mast. We've had nearly-symmetrical sailing performance this summer, once the wind direction instrument was properly calibrated. Tension is greatest for the upper shrouds, with the middle ones just tight enough to keep the mast plumb when close-hauled in mid-teens wind. The actual performance, close-hauled, has been very close to that calculated from the hull's polar diagram. [New sails having something to do with all this, no doubt!]

The measured tensions at rest, mast plumb, visible tension release leeward when under sail, and tacking symmetry are all inputs to the rig tuning process. None is to be taken as an absolute.

--Karl

[chuckr]

Before we left over 8 years ago we had a professional rigger come onboard and tune our rigging and get everything aligned as it is more than the tension on each shroud but getting the mast in the right position.  About once a year I would check the tension with my loos based on what the pro rigger did before we left. 

Before we crossed the Atlantic in 2013 we had a pro rigger do a complete inspection and found a shroud that needed to be changed.  again we had to do a slight readjust. 


In spring 2015 we had a loose shroud and did some adjustments but one turn buckle was a bit frozen so we had a professional rigger come and do a readjust again and it changed slightly. 

So our suggestion would be get a pro rigger tune the rigging and write down the tensions as it is beyond just the tension but getting the mast in the correct position and a bit off can make a bit of difference in your sailing. 

[aussieodyssey]

Mickmeck

This was taken form my Jeanneau 45.5 owners manual .

TRIMMING
An agent has proceed to the first adjustments and cable tension. After few trips you will
have to do the final adjustment to obtain a correct rectitude in transversal; it is also
important to keep the mast rectilinear in longitudinal when sailing.
Therefore, it needs compensation adjustment along side; a first bending of the mast in
longitudinal is required : the middle of the mast bended forward and the head afterward.
The bend must be the half of the mast section.
COMPENSATION ADJUSTMENT:
1 - This is a pushing spreader rigging, so you will have to stretch the upper shrouds before
the backstay.
2 - Stretch tighly all the rigging ( the rigging must be a little bit loosely when sailing with
15-20 knots).
3 - When a perfect transversal and longitudinal rectitude has been obtained, ease t h e
both side aft lower shrouds with 2 turns of bottlescrew.
4 - Finish longitudinal adjustment by stretching tightlier the backstay bottlescrew to
obtain a good stability of the forestay when sailing by 15-20 knots.
Fasten with pins all the bottlescrews and keep this trimming during all the sailing season

Greg