Split backstay tension

[Porthandbuoy]

Sheolin has a split backstay ( not twin backstays ).
I’d like to know how to set them up. Equal tension, obviously, but to 15% using a Loos gauge, or a higher or lower value?

 

[Daydream believer]

Are you fractional or masthead rig? that would be the first thing to know.
I would have thought that if they were of equal length (Exactly) then one would measure the tension of the backstay above the point where they meet. The tension on each split would be 50% of that but every time one adjusts one then the other needs adjusting. Also one needs to consider wire diameter. 15% of a 6mm wire is not the same as 15% of an 8 mm one.
So if the diameter of the wire above the split is greater than the pair in the split then that needs to be the one measured.

 

[alan_d]

I measure mine above the point at which it divides.

 

[LittleSister]

I would have thought that if they were of equal length (Exactly) then one would measure the tension of the backstay above the point where they meet. The tension on each split would be 50% of that

The split stays will each have a tension greater than 50% of the single backstay above, because they are at an angle to the backstay (not in a straight line with it), and part of their tension is pulling the other spilt stay towards it.

I agree that the single stay is the one to measure if practicable. If it is not, then the relevant tension for each lower stay in order to achieve the correct tension in the single backstay can be calculated if the dimensions are known (i.e. length of the split stays, distance apart of their lower attachment).

For measuring purposes you will also need to know the diameters of the backstay and the split stays.

 

[Daydream believer]

LittleSister
You are correct in your statement I was being a bit general. Some backstays join at a greater height than others & I was thinking of those . In that case the amount may be only a little more than 50%. However with a coupling lower down then it could be quite significant in which case I was wrong. But the principle applies- Measure above.

 

[Porthandbuoy]

Can’t measure above the split as it’s inaccessible. It’s approx a 60/40 split. In the meantime I’ve set the lower halves at 10% on the Loos gauge. Feels about right.
Thanks for the advice.

 

[Minerva]

Does the back stay tension matter?

Measure the cap / lowers / intermediates if you have them to get the rig to proper tension. Then adjust the back stay to get the desired prebend in the last and away you go.

If you get too much headsail sag, then apply more backstay/forestry tension maintaining the appropriate prebend.