Hi, I was just looking at the posting on rigging for the an oday 28 and was wondering, since the respondent said "20lbs at shoulder's height" how would one measure this? Also, I just bought an immaculate 27 which had stays undone to put it back in the water and am wondering if I've put too much tension hooking things back up. The backstay could not be turned by hand, and I went and tightened it back to where it appeared to be (the boatyard guy who undid it had disappeared), but this was with a screwdriver through the turnbuckle (where it fit through appropriately)and now I'm wondering...is this considered "hand tight" or should I attempt to free everything and then retighten. The mast and rigging were kept up and on during the winter. The mast looks straight laterally as well as fore and aft, but of course I want it correctly done. Thanks, Douglas Wilson
- Status
- Not open for further replies.
D
Don Evans
Guaging Rig Tension
To guage accurately the tension of a rig you need to purchase a Loos Rig Tension Guage (about $50). There are 2 sizes of guages depending on your wire diameter. Once you have determined the diameter of the stays and shrouds on your boat you can determine the breaking strength of the wire (listed with the guage) then tension the rig using your turnbuckles to a percentage of the breaking strength of the wire. For example if the wire is 7/32" it will have a breaking strength of about 6300 lbs. You can play with the percentages, but a rough estimate would be to apply between 10 and 15% of this to the shrouds so you would guage this, between 630-900lbs, using the Loos guage. A tighter rig (greater than 15%) may improve performance, but there are trade offs to chainplates, hull deformations and wear and tear on the rig. I have mine adjusted to about 12%. In my experience I had my rig to loose, and IMHO I think most boats rig tensions are to loose. People are probably afraid to tighten a rig for fear of breaking something but in most cases you are a long way from that. From what I understand you can actually damage a rig more from shock loading of the rig from being to loose than being too tight (stays going slack than snapping tight...thats when rigging breaks). I think the guage is a handy tool, like the myriad of tools onboard and helps me balance the rig. Don
To guage accurately the tension of a rig you need to purchase a Loos Rig Tension Guage (about $50). There are 2 sizes of guages depending on your wire diameter. Once you have determined the diameter of the stays and shrouds on your boat you can determine the breaking strength of the wire (listed with the guage) then tension the rig using your turnbuckles to a percentage of the breaking strength of the wire. For example if the wire is 7/32" it will have a breaking strength of about 6300 lbs. You can play with the percentages, but a rough estimate would be to apply between 10 and 15% of this to the shrouds so you would guage this, between 630-900lbs, using the Loos guage. A tighter rig (greater than 15%) may improve performance, but there are trade offs to chainplates, hull deformations and wear and tear on the rig. I have mine adjusted to about 12%. In my experience I had my rig to loose, and IMHO I think most boats rig tensions are to loose. People are probably afraid to tighten a rig for fear of breaking something but in most cases you are a long way from that. From what I understand you can actually damage a rig more from shock loading of the rig from being to loose than being too tight (stays going slack than snapping tight...thats when rigging breaks). I think the guage is a handy tool, like the myriad of tools onboard and helps me balance the rig. Don
R
richard
use of guage
How do these guages work? Do you have to start with the stay/shroud under no tension and then go up from there or can they measure an already tightened wire?
How do these guages work? Do you have to start with the stay/shroud under no tension and then go up from there or can they measure an already tightened wire?
D
Don Evans
Guage
You can start with any degree of tension in the stay. You are actually measuring the deflection of the stay at shoulder height, similar to Justin's measure, except the guage has a needle that reflects a scale that reflects the amount of tension in the rig. You attach the guage to the stay and pull out an arm using a cord that moves a needle to a certain point on the scale. That point represents the tension in pounds of breaking strength which you predetermine based on the percentage you wish to have in the stay (say 12 %). Is that as clear as mud...8^) Don
You can start with any degree of tension in the stay. You are actually measuring the deflection of the stay at shoulder height, similar to Justin's measure, except the guage has a needle that reflects a scale that reflects the amount of tension in the rig. You attach the guage to the stay and pull out an arm using a cord that moves a needle to a certain point on the scale. That point represents the tension in pounds of breaking strength which you predetermine based on the percentage you wish to have in the stay (say 12 %). Is that as clear as mud...8^) Don
J
Justin - O'day Owners' Web
Shroud tensions
I agree with Don that most rigs are under tightened but I don't think the gauge is a necessity. I have one and it gets use - whenever a friend asks me to help tune their boat. On my boat, I do it by feel. The 'right' tension is the tension that results in the best sailing boat. Looser than that and you don't point well and risk shock loads. Tighter than that and you're just stressing stuff. Things that matter most are headstay tension to control jib entry and mast rake. I set things up on the 20 pound push theory (a 20 pound push at shoulder height gives an inch of deflection) and then do dynamic tuning. If the jib sags off too much, I tighten the forestay (and backstay equal amounts so the rake doesn't change). If the luff is bar tight I might loosen it. As a practical matter that never happens. If the boat has excessive weather helm even with the main halyard, outhaul, cunningham tight, the mast goes forward slightly. Once the fore and backstay are about right what matters most is relative tension so that rig operates correctly. To this end, the shrouds should be either slightly looser than the forestay/backstay or just tight enough that under your usual sailing conditions the uppers don't get too slack. On my boat this leads to almost as much tension on the upper shrouds as the forestay/backstay. The lowers should be tight enough to keep the mast in column under your regular conditions. Mine are quite tight at the moment but we've been averaging winds in excess of 20 knots so far this season. Balance is everything. Using the gauge is more scientific, certainly. But I think the way to use it best is to set the boat up by feel, then measure tensions with the guage and record them. Next year you'll have a good starting point. Justin - O'day Owners' Web
I agree with Don that most rigs are under tightened but I don't think the gauge is a necessity. I have one and it gets use - whenever a friend asks me to help tune their boat. On my boat, I do it by feel. The 'right' tension is the tension that results in the best sailing boat. Looser than that and you don't point well and risk shock loads. Tighter than that and you're just stressing stuff. Things that matter most are headstay tension to control jib entry and mast rake. I set things up on the 20 pound push theory (a 20 pound push at shoulder height gives an inch of deflection) and then do dynamic tuning. If the jib sags off too much, I tighten the forestay (and backstay equal amounts so the rake doesn't change). If the luff is bar tight I might loosen it. As a practical matter that never happens. If the boat has excessive weather helm even with the main halyard, outhaul, cunningham tight, the mast goes forward slightly. Once the fore and backstay are about right what matters most is relative tension so that rig operates correctly. To this end, the shrouds should be either slightly looser than the forestay/backstay or just tight enough that under your usual sailing conditions the uppers don't get too slack. On my boat this leads to almost as much tension on the upper shrouds as the forestay/backstay. The lowers should be tight enough to keep the mast in column under your regular conditions. Mine are quite tight at the moment but we've been averaging winds in excess of 20 knots so far this season. Balance is everything. Using the gauge is more scientific, certainly. But I think the way to use it best is to set the boat up by feel, then measure tensions with the guage and record them. Next year you'll have a good starting point. Justin - O'day Owners' Web
D
Doug Wilson
Thanks for the good advice!
Hey, Thanks a lot for taking the time to respond. The info you guys have provided will serve me well. I saw the 2nd to the last owner who had her for 16 years and he used both methods with much success. Still winning races he is, but never cracked a thing on this one... Thanks again...
Hey, Thanks a lot for taking the time to respond. The info you guys have provided will serve me well. I saw the 2nd to the last owner who had her for 16 years and he used both methods with much success. Still winning races he is, but never cracked a thing on this one... Thanks again...
- Status
- Not open for further replies.