I am considering an adjustable backstay on my '84 Hunter 34. This is a masthead rig with swept back spreaders. Is this a good idea? It occurs to me that tightening the backstay will necessarily loosen the side stays since they anchor to the deck aft of the mast. Or, is the geometry such that there is enough stretch in the side stays to keep them within an acceptable tension range with the backstay on or off? See what I'm saying?
Adjustable backstay on a masthead rig with swept spreaders
- Thread starter markwbird
- Start date
Re: Adjustable backstay on a masthead rig with swept spreade
I don't have experience with your B&R rig, but I have seen that same cautionary response on these boards that you identify. I'd get advice from a rigger. It does seem logical that you would loosen the stays.
I don't have experience with your B&R rig, but I have seen that same cautionary response on these boards that you identify. I'd get advice from a rigger. It does seem logical that you would loosen the stays.
Mark...
If your mast has been rigged and tuned properly, it should already have a pre-bend in it. The mainsail is usually cut to conform to this set-up. Using an adjuster on the aft shroud may change the way the main performs in a way you may not like.
On my H34 I have the Hyde Streamstay headsail furler, which uses a solid stainless extrusion as the headstay instead of a foil over a wire headstay as is more conventional. Early H34's were so rigged. With such a rigid forestay set-up, bending the mast further may only over-stress the rest of the B&R rigging.
Using a shroud adjuster is common on competition boats, but the H34 wasn't designed with that in mind. You may be better off working with a sailmaker to refine what you do have for better performance. MHO.
If your mast has been rigged and tuned properly, it should already have a pre-bend in it. The mainsail is usually cut to conform to this set-up. Using an adjuster on the aft shroud may change the way the main performs in a way you may not like.
On my H34 I have the Hyde Streamstay headsail furler, which uses a solid stainless extrusion as the headstay instead of a foil over a wire headstay as is more conventional. Early H34's were so rigged. With such a rigid forestay set-up, bending the mast further may only over-stress the rest of the B&R rigging.
Using a shroud adjuster is common on competition boats, but the H34 wasn't designed with that in mind. You may be better off working with a sailmaker to refine what you do have for better performance. MHO.
Adjustable Backstay
Thanks for the responses. The mast does, indeed have a pronounced curve to it. I would like to be able to adjust the headstay tension for different sailing conditions as well as add extra bending to the mast. I do not think that is the type of furler that I have. The name does not ring a bell.
Thanks for the responses. The mast does, indeed have a pronounced curve to it. I would like to be able to adjust the headstay tension for different sailing conditions as well as add extra bending to the mast. I do not think that is the type of furler that I have. The name does not ring a bell.
Re: Adjustable backstay on a masthead rig with swept spreade
Mark, there are some 34's in my area that are raced and they do use a backstay tensioner to "un-sag" the headstay. I think that if the shrouds are correctly tensioned, you'll be able to significantly straighten the forestay without slacking the shrouds.; it will relieve some of the tension on them. Ya gonna have to invest in a tension gauge to get things all even and correct.. Since this is a masthead rig, mast bend (which comes from the diamonds' tension) will be affected very little if any.
Mark, there are some 34's in my area that are raced and they do use a backstay tensioner to "un-sag" the headstay. I think that if the shrouds are correctly tensioned, you'll be able to significantly straighten the forestay without slacking the shrouds.; it will relieve some of the tension on them. Ya gonna have to invest in a tension gauge to get things all even and correct.. Since this is a masthead rig, mast bend (which comes from the diamonds' tension) will be affected very little if any.
Mark, why?
Why do you need to increase headstay tension?
I would presume one of 2 reasons:
1. The furler is too heavy for the stay and causes it to sag. Pulling down on the backstay will only increase mast rake, thus increasing weather helm, which, if you have a sagging headstay, you already have as it is. To remedy this, take up on the forestay instead. If you can't get access to adjust it, it's a fault of the furler design. No good furler precludes, or even inhibits, adjustment of the turnbuckle while the furler is installed. You may need to remove the sail and/or lift up the drum; but the answer 'I can't do that once it's installed' is unacceptable.
2. The furler/extrusion/headstay assembly was cut or fitted too long for the boat. This is amazingly common when less-than-knowledgeable sailors, such as guys in boatyards, fit furlers to production boats, especially when on advice from the owner and not from a rigger. To remedy this, have the furler removed, measured, and compared to the actual working (rigger's) sail plan of the boat.
I'm willing to bet that, of those with furlers and sagging headstays, about 90 percent fall into either the 'too long' or the 'too loose' category. Maybe the rest are something else. I'll think about it.
All this aside, if you have a B&R rig, it really does not benefit from a backstay adjuster. For one thing, a pure B&R rig doesn't even have a backstay; it's designed to stand stiffly without one. Adding a backstay, especially just so to have an adjuster on it, is redundant. One could as well add a plywood daggerboard to the keel.
Also, backstay adjusters start to lose efficiency as the boat gets bigger. We had one on our 9500-lb Raider 33; I don't see much point in one for boats much beyond that. They're mainly for lightweight boats with narrow, flexible spars that benefit from imposing mast bend like they do from shifting crew about the cockpit. Yes; I know there are hydraulic assists; but a hydraulic backstay is the best way I know to propel the mast into the deck or keel, shatter it at the shrouds, or to break its wire-rope fittings. If you can't make the needed improvements with a hand-operated block and tackle, your boat is probably too big to want or need one.
Back in the IOR 1970s stories were legion of people imposing so much added backstay tension that the boat, not the mast, was what bent. We called these 'banana boats'.
And, yes, Mark, the aft lowers will look loose when you bend the mast; that's to be expected. Remember that mast bend works best on close tacks; that's when the headstay needs to be tightest and the forward lowers are doing most of the work against mast pumping (wow and flutter at the spreader point) and the aft lowers aren't as needed for their usual job. Then the backstay adjuster needs to be slacked when going downwind-- which really means that it's just one more thing to constantly play in and out as you go. When you're racing and have 4 or 5 other guys in the cockpit, it's one thing. For 'performance cruising', especially with a cruising-oriented boat crewed mainly by family, I don't see the point.
The advice to consult a professional rigger is well warranted in most cases; definitely it is in this case. I am a professional rigger; so consider yourself as having consulted one. :dance:
Why do you need to increase headstay tension?
I would presume one of 2 reasons:
1. The furler is too heavy for the stay and causes it to sag. Pulling down on the backstay will only increase mast rake, thus increasing weather helm, which, if you have a sagging headstay, you already have as it is. To remedy this, take up on the forestay instead. If you can't get access to adjust it, it's a fault of the furler design. No good furler precludes, or even inhibits, adjustment of the turnbuckle while the furler is installed. You may need to remove the sail and/or lift up the drum; but the answer 'I can't do that once it's installed' is unacceptable.
2. The furler/extrusion/headstay assembly was cut or fitted too long for the boat. This is amazingly common when less-than-knowledgeable sailors, such as guys in boatyards, fit furlers to production boats, especially when on advice from the owner and not from a rigger. To remedy this, have the furler removed, measured, and compared to the actual working (rigger's) sail plan of the boat.
I'm willing to bet that, of those with furlers and sagging headstays, about 90 percent fall into either the 'too long' or the 'too loose' category. Maybe the rest are something else. I'll think about it.
All this aside, if you have a B&R rig, it really does not benefit from a backstay adjuster. For one thing, a pure B&R rig doesn't even have a backstay; it's designed to stand stiffly without one. Adding a backstay, especially just so to have an adjuster on it, is redundant. One could as well add a plywood daggerboard to the keel.
Also, backstay adjusters start to lose efficiency as the boat gets bigger. We had one on our 9500-lb Raider 33; I don't see much point in one for boats much beyond that. They're mainly for lightweight boats with narrow, flexible spars that benefit from imposing mast bend like they do from shifting crew about the cockpit. Yes; I know there are hydraulic assists; but a hydraulic backstay is the best way I know to propel the mast into the deck or keel, shatter it at the shrouds, or to break its wire-rope fittings. If you can't make the needed improvements with a hand-operated block and tackle, your boat is probably too big to want or need one.
Back in the IOR 1970s stories were legion of people imposing so much added backstay tension that the boat, not the mast, was what bent. We called these 'banana boats'.
And, yes, Mark, the aft lowers will look loose when you bend the mast; that's to be expected. Remember that mast bend works best on close tacks; that's when the headstay needs to be tightest and the forward lowers are doing most of the work against mast pumping (wow and flutter at the spreader point) and the aft lowers aren't as needed for their usual job. Then the backstay adjuster needs to be slacked when going downwind-- which really means that it's just one more thing to constantly play in and out as you go. When you're racing and have 4 or 5 other guys in the cockpit, it's one thing. For 'performance cruising', especially with a cruising-oriented boat crewed mainly by family, I don't see the point.
The advice to consult a professional rigger is well warranted in most cases; definitely it is in this case. I am a professional rigger; so consider yourself as having consulted one. :dance:
J. C. ...
Unlike many other masthead rigs, the B&R rig on the H34 doesn't have fore and aft lowers. It does have significantly swept-back spreaders. The outer upper shrouds are brought down to the deck on the vertical, aft of the mast base position through these spreaders. The D1 shrouds run from the lower spreader attachment point on the mast to the shroud plate on the deck, where the outer shrouds are also attached. See attached.
The mast would probably stay up without the backstay as is done on the newer B&R rigged boats.
All the mast tuning is done on the ground before the mast is returned to the boat and raised.
Unlike many other masthead rigs, the B&R rig on the H34 doesn't have fore and aft lowers. It does have significantly swept-back spreaders. The outer upper shrouds are brought down to the deck on the vertical, aft of the mast base position through these spreaders. The D1 shrouds run from the lower spreader attachment point on the mast to the shroud plate on the deck, where the outer shrouds are also attached. See attached.
The mast would probably stay up without the backstay as is done on the newer B&R rigged boats.
All the mast tuning is done on the ground before the mast is returned to the boat and raised.
Attachments
Why?
Thanks again everyone for the great input. The answer to Diana's question as to "why" is that I want to race the boat and I want to be able to adjust the forestay tension and possibly mast bend for all the same reasons that anybody who races wants to do those things. This is not an issue of the rig being out of tune (although it probably is). It is just a question of whether an adjustable backstay is: (1) effective for this type of rig and (2) problematic for this type of rig.
Thanks again everyone for the great input. The answer to Diana's question as to "why" is that I want to race the boat and I want to be able to adjust the forestay tension and possibly mast bend for all the same reasons that anybody who races wants to do those things. This is not an issue of the rig being out of tune (although it probably is). It is just a question of whether an adjustable backstay is: (1) effective for this type of rig and (2) problematic for this type of rig.
Mark...
The hot-shoe racer across the dock from me rigged an adjuster by putting a pair of blocks over the lower backstay wires on his split backstay, hooked together with a shackle on his 33.5 and pulled them down with a 3:1 downhaul to do what you want. Seemed to work for him!
The hot-shoe racer across the dock from me rigged an adjuster by putting a pair of blocks over the lower backstay wires on his split backstay, hooked together with a shackle on his 33.5 and pulled them down with a 3:1 downhaul to do what you want. Seemed to work for him!
Re: Adjustable backstay on a masthead rig with swept spreade
Dan, if I'm not mistaken the 33.5 is a fractional rig so the backstay adjuster is going to be much more useful than on our masthead rigs. I have had my boat for 15 years with a Profurl roller furler and have also had the same backstay tensioner set-up as your dock neighbor for as long. To answer Markwbird's questions I'd have to go with Diana's explanation. My rig is well tuned and the tension on headstay, backstay and shrouds is on the higher side of the spec ranges. Consequently, the headstay stays straight with the 130 fully out up about 18 knots of wind. By then, I can pull on the backstay tensioner and the headstay will get a little straighter. But our 34s being tender, it is generally easier to furl down to about a 110 and I get a better balanced boat, hence faster with less weatherhelm. Winds above 20, I do need to reef the main. BTW, the shrouds do tend to loose some tension with backstay tensioner usage because of the 30 degrees sweptback spreaders. And Diana is right that the backstay on our B & R rig is almost redondant. In fact I have sailed in very light winds with it completely loose without any problems. In a nutshell, Mark, I don't find it as effective as I have on fractional rigs I've raced on, but I don't find it problematic either (maybe because I'm careful when using it).
Dan, if I'm not mistaken the 33.5 is a fractional rig so the backstay adjuster is going to be much more useful than on our masthead rigs. I have had my boat for 15 years with a Profurl roller furler and have also had the same backstay tensioner set-up as your dock neighbor for as long. To answer Markwbird's questions I'd have to go with Diana's explanation. My rig is well tuned and the tension on headstay, backstay and shrouds is on the higher side of the spec ranges. Consequently, the headstay stays straight with the 130 fully out up about 18 knots of wind. By then, I can pull on the backstay tensioner and the headstay will get a little straighter. But our 34s being tender, it is generally easier to furl down to about a 110 and I get a better balanced boat, hence faster with less weatherhelm. Winds above 20, I do need to reef the main. BTW, the shrouds do tend to loose some tension with backstay tensioner usage because of the 30 degrees sweptback spreaders. And Diana is right that the backstay on our B & R rig is almost redondant. In fact I have sailed in very light winds with it completely loose without any problems. In a nutshell, Mark, I don't find it as effective as I have on fractional rigs I've raced on, but I don't find it problematic either (maybe because I'm careful when using it).
Hey Claude...
I recognize that the 33.5 is fractional. I was pointing out that an adjuster could be rigged easily without having to buy one specificly designed for that purpose.
I failed to mention that the two blocks were attached by shackles to the ends of a spread-out SS spinaker pole hoop to which the downhaul block was attached on the hoop portion.
BTW, with a rigid headstay I don't suffer "droop", and fly just a reefing 110 on it anyway. The backstay may be redundant, but I'd rather it take up the windload tension going downwind than putting it on the mainsail & its sheeting as the newer B&R rigging does.
I recognize that the 33.5 is fractional. I was pointing out that an adjuster could be rigged easily without having to buy one specificly designed for that purpose.
I failed to mention that the two blocks were attached by shackles to the ends of a spread-out SS spinaker pole hoop to which the downhaul block was attached on the hoop portion.
BTW, with a rigid headstay I don't suffer "droop", and fly just a reefing 110 on it anyway. The backstay may be redundant, but I'd rather it take up the windload tension going downwind than putting it on the mainsail & its sheeting as the newer B&R rigging does.
Hi Dan
I am in total agreement as to also preferring to rely on the backstay, particularly since I quite often unfurl my 130 completely and run with it rather than bothering with the main pressured on the tips of the spreaders. My headstay is rigid enough as mentioned that until I get above 18 knots there is no droop. and then I furl to about a 110 which then brings me in the same range you are.
Easisly rigged adjuster: That was my point too in describing my set-up.
I am in total agreement as to also preferring to rely on the backstay, particularly since I quite often unfurl my 130 completely and run with it rather than bothering with the main pressured on the tips of the spreaders. My headstay is rigid enough as mentioned that until I get above 18 knots there is no droop. and then I furl to about a 110 which then brings me in the same range you are.
Really??? You've never heard of matching headstay sag to wind conditions?