removehtml]Hello all. This week I'm unstepping the mast on my 1987 H31 to replace the lower spreaders and the standing rigging, and I hope to put it all back together next week. Hah. Anyway, I've perused the archives, and I have the B&R tuning procedures from my Hunter manual, along with the html B&R reference article from this site, but before I get started on this fun-filled project, I'd like to solicit any advice, words of wisdom, or helpful hints from anyone out there who has the inclination to chime in. Among other things, I was wondering if I need a Loos guage for pre-tuning the mast prior to re-stepping it, and/or for tuning the rig after stepping the mast; and if so, how many pounds of tension would be appropriate for the various components of the rig. The published procedures say things like "Tighten the forestay up to approximately 25% of the final tension you will want on it." Huh? Or: "The forestay and backstay should have a reasonable amount of tension on them." And this: "Start by adjusting the uppers... until they are tight" and then: "Tighten the intermediate shrouds... until they are almost as tight as the uppers." It all just seems just a bit nebulous, really... but maybe I'm just being a pinhead. Any and all advice would be GREATLY appreciated! Thanks in advance- RickError: Error: expected [/URL], but found [/removehtml] instead[/removehtml]
Stepping the mast and tuning the B&R rig: any advice?
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Here are some suggestions on the B & R tuning...
RJ I've had three Hunter sailboats with some form of the B & R rig. I did the Hunter 40 myself--we laid out the mast, added the spreaders and then the wire. We pre-tensioned the diamonds and then set it on the boat and attached shrouds, fore and aft stays. Done. My present boat was put together by a shipyard in Seattle and then I took it to Port Townsend to have Brion Toss inspect and tune the rig. Brion is one of the top riggers in the Pacific Northwest--his web site is: http://briontoss.com/ . When he tuned my rig he went to the top and pulled on the shrouds to see if one or the other appeared slacker. Then he "hit" them with a wrench and literally tuned them to the same sound. If one side went "twang" and the other side went "thunk" he adjusted one side or the other. He also came down several times and sighted up the mast. His advice to me was that the B & R rig is pre-stress and then you place it on the boat and tighten the three sides to keep the mast straight up. IF you have roller furling main like I do then there should be no curve in the mast as in the more traditional rigs. My Hunter 40 had a curve in the mast aft about 10 inches pre-stress into the mast before it went on the boat. But my present mast is entirely straight. Once Brion had the top "balanced" then is moved down the mast to the next spreaders and again pulled one side then the other on the wire. IF he felt there were about the same, then he "tuned" them by hitting and listening to the sounds. At this stage he also had a length of wire that he used to measure from the mast to the outside of the boat. This was to insure that the mast was essentially straight on the boat. He mentioned this was an important point. One of the beauties of this mast is that it is pre-stress and then placed on the boat so you don't have to pull the ends and sides up of your boat like a bow and arrow. [I had a racing boat that we pull the fore and aft ends up about two inches with a hydraulic backstay adjuster.] Brion also said in passiing that this would be the rig of choice if he were sailing around the world. It is the strongest rig there is. Brion Toss took about three hours to tune my rig with the help of two interns who did the adjusting at the base. By the way, Brion did not use cotter pins or circular rings to maintain the rig--rather he used stainless steel welding rods and bent them in place. He said they were stronger and looked better and were easier to remove and replace. Hope this helps... Les
RJ I've had three Hunter sailboats with some form of the B & R rig. I did the Hunter 40 myself--we laid out the mast, added the spreaders and then the wire. We pre-tensioned the diamonds and then set it on the boat and attached shrouds, fore and aft stays. Done. My present boat was put together by a shipyard in Seattle and then I took it to Port Townsend to have Brion Toss inspect and tune the rig. Brion is one of the top riggers in the Pacific Northwest--his web site is: http://briontoss.com/ . When he tuned my rig he went to the top and pulled on the shrouds to see if one or the other appeared slacker. Then he "hit" them with a wrench and literally tuned them to the same sound. If one side went "twang" and the other side went "thunk" he adjusted one side or the other. He also came down several times and sighted up the mast. His advice to me was that the B & R rig is pre-stress and then you place it on the boat and tighten the three sides to keep the mast straight up. IF you have roller furling main like I do then there should be no curve in the mast as in the more traditional rigs. My Hunter 40 had a curve in the mast aft about 10 inches pre-stress into the mast before it went on the boat. But my present mast is entirely straight. Once Brion had the top "balanced" then is moved down the mast to the next spreaders and again pulled one side then the other on the wire. IF he felt there were about the same, then he "tuned" them by hitting and listening to the sounds. At this stage he also had a length of wire that he used to measure from the mast to the outside of the boat. This was to insure that the mast was essentially straight on the boat. He mentioned this was an important point. One of the beauties of this mast is that it is pre-stress and then placed on the boat so you don't have to pull the ends and sides up of your boat like a bow and arrow. [I had a racing boat that we pull the fore and aft ends up about two inches with a hydraulic backstay adjuster.] Brion also said in passiing that this would be the rig of choice if he were sailing around the world. It is the strongest rig there is. Brion Toss took about three hours to tune my rig with the help of two interns who did the adjusting at the base. By the way, Brion did not use cotter pins or circular rings to maintain the rig--rather he used stainless steel welding rods and bent them in place. He said they were stronger and looked better and were easier to remove and replace. Hope this helps... Les
Tuning after Replacement
Hi Rick, This is how I did mine: Get a long tape measure (50' at least) I made sure that all the various components that were on opposite sides of the mast were exatly the same length to start with. That included the turnbuckle barrels and bottom toggles. That way the mast should be straight when you tighten opposite sides equally. I also got antisieze compound for any fasteners that will go back through the mast (spreader to mast bolts, pins at the end of the spreaders, etc.). Also, buy some nylon washers to put between the tangs and the mast just to help reduce some of that dissimilar metal to metal contact. They have them at West Marine. After you put all the rigging on (the mast is still on saw horses I presume) tighten all four diagonals evenly a little at a time. Count the number of turns on the turnbuckles. You will start to see the prebend appear in the mast. Pull a string from the top to the bottom. Tighten the diagonals until the distance from the string back to the center of the bend is about 1% of the total length of the mast. You can now have the mast put back on. Make sure the turnbuckles are either tightened the same amount on the port and starboard shrouds or measure the amount of thread exposed inside the barrels and that it is the same on its opposite mate. Get it tight enough that the mast isn't able to rock side to side. This is all just rough tuning....don't want it to fall over. Tighten the forestay turnbuckle to about where it had been before. You can then tighten the backstay turnbuckles (equally again) to apply more tension on the forestay. At this point you can hoist your tape measure all the way to the top with the main halyard. Measure to a common point on each side of the boat and make sure then that the mast is plumb. If you have to adjust, then loosen the shroud turnbuckles on the low side and then tighten the opposite sides exactly the same number of turns. Now it should be straight and ready for final tuning. I took mine out for a sail in 10 knots of wind (no more than that). When sailing close hauled with all the sails up, I would tighten the leeward shrouds until the slack was just removed. Tack and tighten the new leeward side exactly the same amount of turns. Repeat a few times until there is no more slack on the leeward side at that 10 knot breeze. When standing straight up (motoring into the wind or back at the dock) the rigging will feel tight. You most likely will have to tighten the backstays again too as the mast will pull back some when the shrouds are tightened. I just tighten it enough to neutralize the slack, but not so tight that I begin to slacken the shrouds again. Otherwise you have to start all over. Over time I tweaked things to get more or less mast rake to improve weather helm, but otherwise I was pleased with the result. Its not very scientific, but eventually you can dial in that extra 1/4 knot of performance if you are trying to compete in a race. Regards, Allan
Hi Rick, This is how I did mine: Get a long tape measure (50' at least) I made sure that all the various components that were on opposite sides of the mast were exatly the same length to start with. That included the turnbuckle barrels and bottom toggles. That way the mast should be straight when you tighten opposite sides equally. I also got antisieze compound for any fasteners that will go back through the mast (spreader to mast bolts, pins at the end of the spreaders, etc.). Also, buy some nylon washers to put between the tangs and the mast just to help reduce some of that dissimilar metal to metal contact. They have them at West Marine. After you put all the rigging on (the mast is still on saw horses I presume) tighten all four diagonals evenly a little at a time. Count the number of turns on the turnbuckles. You will start to see the prebend appear in the mast. Pull a string from the top to the bottom. Tighten the diagonals until the distance from the string back to the center of the bend is about 1% of the total length of the mast. You can now have the mast put back on. Make sure the turnbuckles are either tightened the same amount on the port and starboard shrouds or measure the amount of thread exposed inside the barrels and that it is the same on its opposite mate. Get it tight enough that the mast isn't able to rock side to side. This is all just rough tuning....don't want it to fall over. Tighten the forestay turnbuckle to about where it had been before. You can then tighten the backstay turnbuckles (equally again) to apply more tension on the forestay. At this point you can hoist your tape measure all the way to the top with the main halyard. Measure to a common point on each side of the boat and make sure then that the mast is plumb. If you have to adjust, then loosen the shroud turnbuckles on the low side and then tighten the opposite sides exactly the same number of turns. Now it should be straight and ready for final tuning. I took mine out for a sail in 10 knots of wind (no more than that). When sailing close hauled with all the sails up, I would tighten the leeward shrouds until the slack was just removed. Tack and tighten the new leeward side exactly the same amount of turns. Repeat a few times until there is no more slack on the leeward side at that 10 knot breeze. When standing straight up (motoring into the wind or back at the dock) the rigging will feel tight. You most likely will have to tighten the backstays again too as the mast will pull back some when the shrouds are tightened. I just tighten it enough to neutralize the slack, but not so tight that I begin to slacken the shrouds again. Otherwise you have to start all over. Over time I tweaked things to get more or less mast rake to improve weather helm, but otherwise I was pleased with the result. Its not very scientific, but eventually you can dial in that extra 1/4 knot of performance if you are trying to compete in a race. Regards, Allan
Tuning the B&R Rig
Alan, Very well written and exactly on mark. The only thing that I would add is that if you find your headsail luff too slack when going upwind you tighten the uppers to increase the tension, but, be carefull not to exceed 20% of breaking strength of upper shrouds. Dennis W. S/V FullSailed
Alan, Very well written and exactly on mark. The only thing that I would add is that if you find your headsail luff too slack when going upwind you tighten the uppers to increase the tension, but, be carefull not to exceed 20% of breaking strength of upper shrouds. Dennis W. S/V FullSailed
Good advice Dennis
Excellent advice Dennis. I actually never did that. I've owned this boat since 1985 and I'm still learning how to tweak it. Allan
Excellent advice Dennis. I actually never did that. I've owned this boat since 1985 and I'm still learning how to tweak it. Allan
tuning the headstay
Someone mentioned that "if you find your headsail luff too slack when going upwind you tighten the uppers to increase the tension..." On a frac rig, the headstay on your boat is tensioned by the upper shrouds primarily and minimally by the backstay. After you set your mast rake, the length of the headstay should no longer be adjusted. Use a Loos gauge on the upper shrouds and tighten to 15% of break tension. Then adjust the lowers to the same. The intermediates are used to adjust mast prebend. One mast diameter is an average number. After going through this, recheck the uppers and increase to 20% if the headstay still feels too loose.
Someone mentioned that "if you find your headsail luff too slack when going upwind you tighten the uppers to increase the tension..." On a frac rig, the headstay on your boat is tensioned by the upper shrouds primarily and minimally by the backstay. After you set your mast rake, the length of the headstay should no longer be adjusted. Use a Loos gauge on the upper shrouds and tighten to 15% of break tension. Then adjust the lowers to the same. The intermediates are used to adjust mast prebend. One mast diameter is an average number. After going through this, recheck the uppers and increase to 20% if the headstay still feels too loose.
Great input..
Alan and Les you guys took alot of time to post your input. I am watching this post closely because I too want to learn more about this tuning process. I have no experience with tuning the rig and use this forum to learn. RJ and I probably have the same rig, just slightly different lengths. In the pre-bend process - do you only have a horse on each end - cause the length and mast weight may cause a pre-bend by itself. Lets go thru some numbers real quick for a sanity check. Lets say that the mast length is 48 ft. (its close enough for this example) so the prebend length needs to be 48 * .99 = 47.5 ft? That gives about a 3.5 ft curve to the mast. Is the tightning to get the 47.5 ft. only on the upper diamonds? Because on RJ's and my rig there is 1 lower to the mast base from the intermediate spreader. If it is both the intermediate diamond and the lower what should the percentage be? Should it be equal because I dont think the distances are equal. Also, should there be any angle on the spreader - should it be perpendicular with the mast or should it slope down slightly? Once you have the pre-bend, the rest of the explanation was great. I just had a little trouble with the pre-bend and how to get it.
Alan and Les you guys took alot of time to post your input. I am watching this post closely because I too want to learn more about this tuning process. I have no experience with tuning the rig and use this forum to learn. RJ and I probably have the same rig, just slightly different lengths. In the pre-bend process - do you only have a horse on each end - cause the length and mast weight may cause a pre-bend by itself. Lets go thru some numbers real quick for a sanity check. Lets say that the mast length is 48 ft. (its close enough for this example) so the prebend length needs to be 48 * .99 = 47.5 ft? That gives about a 3.5 ft curve to the mast. Is the tightning to get the 47.5 ft. only on the upper diamonds? Because on RJ's and my rig there is 1 lower to the mast base from the intermediate spreader. If it is both the intermediate diamond and the lower what should the percentage be? Should it be equal because I dont think the distances are equal. Also, should there be any angle on the spreader - should it be perpendicular with the mast or should it slope down slightly? Once you have the pre-bend, the rest of the explanation was great. I just had a little trouble with the pre-bend and how to get it.
Fantastic advice!
Thanks a million, everyone! I've also got a couple of notes from the B&R Tuning guide in my Hunter manual that answer a some of GuyT's questions: Any additional practical input would, of course, be appreciated. First, my H31 manual indicates that the mast should be supported in 3 places: at it's center and, at 1/4 of it's length on either side of the center support. Second, and it's probably just a typo in Guy's post, but I think 6 inches (.5 feet vs. vs. 3.5 feet)of pre-bend would be appropriate for the 50 foot mast example. And that 50' refers to mast height above the boom, or your 'P' dimension, vs. mast length overall, as far as I can tell. And my manual states that d1 and d2, the upper and lower diamonds, should be tightened equally to achieve the pre-bend. Thanks again everybody! Rick
Thanks a million, everyone! I've also got a couple of notes from the B&R Tuning guide in my Hunter manual that answer a some of GuyT's questions: Any additional practical input would, of course, be appreciated. First, my H31 manual indicates that the mast should be supported in 3 places: at it's center and, at 1/4 of it's length on either side of the center support. Second, and it's probably just a typo in Guy's post, but I think 6 inches (.5 feet vs. vs. 3.5 feet)of pre-bend would be appropriate for the 50 foot mast example. And that 50' refers to mast height above the boom, or your 'P' dimension, vs. mast length overall, as far as I can tell. And my manual states that d1 and d2, the upper and lower diamonds, should be tightened equally to achieve the pre-bend. Thanks again everybody! Rick
Pre bend arc
I came up with the 3.5 ft. the following way. I used 48 ft, so the middle is 24 ft. The middle was my bending point. I also used 47.5 ft for the prebend length or 23.75 ft to the middle right above the 24 ft middle of mast mark. To find out the distance I used an approximation by using two straight lines and a^2 + b^2 = c^2. Pythagorean theory. (^2 is a square symbol) 23.75^2 + b^2 = 24^2. b=3.5 So, 3.5 ft is an approximation - errors on the high side, but is surely is closer than 6 inches. Its probably more like a couple of feet. I think the 47.5 ft is the number to measure, not the distance of the arc. Thanks for the info RJ, I have copied this post into my toolbag!
I came up with the 3.5 ft. the following way. I used 48 ft, so the middle is 24 ft. The middle was my bending point. I also used 47.5 ft for the prebend length or 23.75 ft to the middle right above the 24 ft middle of mast mark. To find out the distance I used an approximation by using two straight lines and a^2 + b^2 = c^2. Pythagorean theory. (^2 is a square symbol) 23.75^2 + b^2 = 24^2. b=3.5 So, 3.5 ft is an approximation - errors on the high side, but is surely is closer than 6 inches. Its probably more like a couple of feet. I think the 47.5 ft is the number to measure, not the distance of the arc. Thanks for the info RJ, I have copied this post into my toolbag!
The Prebend is only 1%
Just for clarification: The correct amount of prebend for a 50 foot mast as measured by the distance from a straight line (i.e., a string) to the mast is 50 ft x 12 in/ft x .01 = 6 in. The sail is cut this way, so it fits nicely all the way up the mast. Allan
Just for clarification: The correct amount of prebend for a 50 foot mast as measured by the distance from a straight line (i.e., a string) to the mast is 50 ft x 12 in/ft x .01 = 6 in. The sail is cut this way, so it fits nicely all the way up the mast. Allan
Yikes..Reason for Mast Curve
Hi All, I am very interested in this Thread as I need to assemble the B&R rig on my Hunter 306 this spring. I am especially interested in the comments on the Mast Curve. One of the previous posters mentioned Brion Toss telling him there should be no curve on a inmast furling setup. Does anyone have any comments on this. Also as regards the Mast curve in general does anyone know the reason it is there. I am familiar with the mast prebend from sailing beach catamarans. On these boats we prebend the mast and then use a powerful downhaul or cunningham. The prebend makes it easier to bend the mast further using the downhaul and alter the shape and power of the sail. On a larger keelboat with no downhaul, no backstay and a much stiffer mast I cannot understand why we prebend the mast. When people discuss tuning the mast they never even mention the sails but surely the amount of prebend we use must be related to the shape of the luff on the main. I would appreciate any help out there in understanding this topic Thanks / Aidan
Hi All, I am very interested in this Thread as I need to assemble the B&R rig on my Hunter 306 this spring. I am especially interested in the comments on the Mast Curve. One of the previous posters mentioned Brion Toss telling him there should be no curve on a inmast furling setup. Does anyone have any comments on this. Also as regards the Mast curve in general does anyone know the reason it is there. I am familiar with the mast prebend from sailing beach catamarans. On these boats we prebend the mast and then use a powerful downhaul or cunningham. The prebend makes it easier to bend the mast further using the downhaul and alter the shape and power of the sail. On a larger keelboat with no downhaul, no backstay and a much stiffer mast I cannot understand why we prebend the mast. When people discuss tuning the mast they never even mention the sails but surely the amount of prebend we use must be related to the shape of the luff on the main. I would appreciate any help out there in understanding this topic Thanks / Aidan
Rig tuning
Aidan I think the attached link from Selden will explain the theory and tuning and also covers masthead rigging about which you might not be interested but makes a contrasting comparison and should answer your questions
Aidan I think the attached link from Selden will explain the theory and tuning and also covers masthead rigging about which you might not be interested but makes a contrasting comparison and should answer your questions
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