A back-stay tensioner on a mast head rig will have little impact as you would not be able to stretch the forestay much 0.2% max then it would break. It would tighten the forestay if it was loose, but it shouldn't be! They are designed for fractional rigs where the top of the mast can move.
A back-stay tensioner on a mast head rig will have little impact as you would not be able to stretch the forestay much 0.2% max then it would break. It would tighten the forestay if it was loose, but it shouldn't be! They are designed for fractional rigs where the top of the mast can move.
That's strange, as I think I've seen numerous pics of LM27s with backstay tensioners.
The LM27 rigging trim guide* provided by LM says the mast should normally have 5cm (2") bend, and this should be increased to 10cm (4") from Force 4 upwards. It doesn't say how the latter is to achieved, but I can't imagine that one would be repeatedly adjusting the forward lowers underway.
I read the guide too and wondered how you could adjust the tension. My last boat was a lot more "sporty" (and a lot less comfortable) we regularly increased tension on the back stay as the wind strength increased and we wanted a flatter more controllable main.
Post by Brian & Glenda on Mar 17, 2020 18:11:11 GMT
Here is a link to a good article on backstay tension... For those of us without backstay tensioning devices, mast bend is said to be somewhat controlled by tensioning the mainsheets; but I've never measured how much bend can be introduced that way in the sturdy John Mast on my LM32.
I've read around the backstay tension issue a bit - both with articles like the Quantum one Brian and Glenda posted, and with various sailing forum discussions. It seems in the latter there are regularly two (maybe more!) camps with mutually irreconcilable views.
Some, like paulsailing, maintain that tensioning the backstay on a masthead rig can't possibly affect mast bend; and others say they've got masthead rigs and the mast bend definitely is increased when the backstay is wound up!
Post by Brian & Glenda on Mar 19, 2020 19:49:27 GMT
I think it all depends on how flexible your mast is. If you apply forward pressure along your boom by tightening the vang, the mainsail outhaul, and the mainsheets; if your mast is flexible enough, it will bend. As you noted above Sula, LM gave us mast bend specs for our masthead rigs, and they gave us the mast and fittings they felt were right for the boat... so it must be possible to bend the LM mast! I'll have to study that further next time I'm out playing on the water.... Cheers, Brian.