On a rig without a backstay (B&R), would it be safe to say that you want to be near the upper limits of tension to be sure headstay sag is controlled as much as possible?
Headstay sag B&R
- Thread starter Quoddy
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No. I bought a Loos pro tension guage, set the rig according to recomendations in Seldens booklet and the instructions that came with the gauge. Once the mast is up I attach the Loos and tighten the turnbuckle watching the Guage. No problem. Spend the money so you'l KNOW, not just guess. And no, I do not go alomg with tuning it like a guitar. Baloney. Neither of us is Keith Richards, nor is it 1850 AD. any more.
Sam, I sure hope you didn't put the Loos gauge on the headstay. I hope you mean that tensioning the cap shrouds to induce tension in the headstay is what you meant. The headstay turnbuckle is ONLY adjusted to control mast rake. It is NEVER used to tension the headstay. Mast rake is an adjustment to balance sailing forces. The amount of tension in that stay is a controller of sail shape.
Quoddy, unfortunately when you give up something like a backstay there is a price to be paid. Yes, it does help to unclutter the cockpit and not having a backstay adjuster is just one less line to pull. The downside is you give up a sail control that helps to shape your sails. The result is a compromise between headstay tension for upwind sailing where you would want maximum tension and downwind sailing where you would want a loose headstay.
Quoddy, unfortunately when you give up something like a backstay there is a price to be paid. Yes, it does help to unclutter the cockpit and not having a backstay adjuster is just one less line to pull. The downside is you give up a sail control that helps to shape your sails. The result is a compromise between headstay tension for upwind sailing where you would want maximum tension and downwind sailing where you would want a loose headstay.
Bias towards upwind
The boat has high freeboard, internal ballast and a centerboard. I think looking at improving upwind performance might be more effective than improving downwind performance. As I understand it, a rounded jib entry due to forestay sag will hurt pointing ability.
The boat has high freeboard, internal ballast and a centerboard. I think looking at improving upwind performance might be more effective than improving downwind performance. As I understand it, a rounded jib entry due to forestay sag will hurt pointing ability.
You can bet your butt it will. Set your cap shrouds(uppers) at 25% of SWL and that will give you the best possible headstay tension that your rig will produce. Adjust the lower shrouds after to get the desired prebend in the mast.
Don't forget to ease the both halyards and outhaul while heading down then reset them just before you turn uphill again.
Don't forget to ease the both halyards and outhaul while heading down then reset them just before you turn uphill again.
Alan,
Sorry to be contradictory but on my H376 the natural stretch in the 1X19 forestay at 25% of the breaking load of the wire (i.e. stretch=31mm) accounts for approx 115mm (4 1/2") of mast rake.
If one sets the rake up at 6" with only just enough tension to hold the mast steady then the rake at full shroud tension increases by a further 4 1/2" which means the result is almost double the recommended rake.
Accordingly I adjust the forestay whilst setting up the shrouds
Sorry to be contradictory but on my H376 the natural stretch in the 1X19 forestay at 25% of the breaking load of the wire (i.e. stretch=31mm) accounts for approx 115mm (4 1/2") of mast rake.
If one sets the rake up at 6" with only just enough tension to hold the mast steady then the rake at full shroud tension increases by a further 4 1/2" which means the result is almost double the recommended rake.
Accordingly I adjust the forestay whilst setting up the shrouds
Donalex,
There's no contradiction. Mast rake is measured on a fully tensioned rig and thus includes any stretch in all wire stays. My point in mentioning the Loos gauge was to clarify that Sam was measuring and adjusting shroud tension not headstay length. My apologies for the confusion.
There's no contradiction. Mast rake is measured on a fully tensioned rig and thus includes any stretch in all wire stays. My point in mentioning the Loos gauge was to clarify that Sam was measuring and adjusting shroud tension not headstay length. My apologies for the confusion.
Thanks for suggestions
I use the Loos basic. I check the rake, then tighten the rig, then loosen readjust and re-tighten until rake and prebend and tension are just right. I had been using 15-20%. I will try going to 25% and see if that makes us fly into the wind.
I use the Loos basic. I check the rake, then tighten the rig, then loosen readjust and re-tighten until rake and prebend and tension are just right. I had been using 15-20%. I will try going to 25% and see if that makes us fly into the wind.
Selden has a down loadable rig tuning guide on their web site - including a whole section on tuning a B&R. The guide includes a method to calculate rig tension with a ruler. Very useful if you don't have a gauge and accurate enough for cruisers.
Carl
Carl
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