Don - Our Legend 37.5 is a B&R fractional rig with swept back spreaders and a single backstay with dual connections to the boat. There is no way to tension the backstay. When the wind picks up, the genoa sags. Will we be able to eliminate this sag by tensioning the backstay? What other advantages can be gained by having a means to apply tension to the backstay on this rig? Thanks
Backstay Tensioner
- Thread starter Steve Carpman11081
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Steve: Let's talk a little about why we want to bend the mast in the first place. The mainsail looks triangular but it isn't. It is built with an exaggerated leech and has excess luff curve. When you bend the mast your trying to get the mast to match to the luff curve thus pulling out the fullness in the middle of the sail. To see what I'm talking about, assume your index finger is the mast. Now bend your finger. See how the knuckle goes backwards. That action is pulling the fullness out of the middle of the sail and it gets flatter. Additionally, the draft position (which I'll explain shortly) moves aft, which is a more powerful position. The only time you want to bend the mast is when you are sailing upwind. Going downwind you'd want to bend it forward if you could but you really can't do that. The problem with production boats like Catalina, Hunter, Benny etc is that trying to bend the mast is like trying to bend a telephone pole!! You will never get it to look like a "J" boat mast, which is the real object. Part of my problem in discussing the Hunter B&R rig is that I've never sailed on one so it is hard to visualize what is happening. There are 2 Hunters on my dock and they do not have backstay tensioners. I've never met the owners but I wonder how they deal with the problem. Maybe some of the Hunters owners on this Forum could help us out.
Don,
I need to bring you up to speed on this one. The L37.5 is fractionally rigged but is not a B&R rig. B&R rigs can be identified by their diagonal shrouds. The Legend Series of Hunters are all traditional fractional rigs with swept spreaders but are NOT B&R. With regard to the backstay: It will flatten the main but it fails to tension the headstay which is also vitally important for depowering on a beat when the wind increases. A jumper strut on the mast or runners are needed to cure this. Also the mast on these boats is particularly bendy, unlike your Cat30 telephone pole.
I need to bring you up to speed on this one. The L37.5 is fractionally rigged but is not a B&R rig. B&R rigs can be identified by their diagonal shrouds. The Legend Series of Hunters are all traditional fractional rigs with swept spreaders but are NOT B&R. With regard to the backstay: It will flatten the main but it fails to tension the headstay which is also vitally important for depowering on a beat when the wind increases. A jumper strut on the mast or runners are needed to cure this. Also the mast on these boats is particularly bendy, unlike your Cat30 telephone pole.
backstay tensioner with swept spreaders
A backstay tensioner is not normally used with swept spreaders because pulling the mast truck aft loosens the uppers and the uppers are bearing forward pressure at the spreaders. The forward pressure is necessary because of no forward lowers. As Alan infers, unless diagonals are used to load the spreaders, a backstay tensioner while firming up the headstay and depowering the headsail, would power up the main with not much gained. A work around to enable backstay tensioner use beside diagonals is a baby stay to hold the middle of the mast forward when the backstay tensioner is engaged. On my C250 used primarily for cruising, there is no place or space for a standing rig baby stay so used is a running rig baby stay. It is a low stretch line from the spreaders through a block at the stem and back to a sheet winch. It uses a bungee which drops from the spreaders to a mast base turning block and forward to the line which serves as an auto retract line on the stay... in other words, when the running baby stay is released, the bungee retracts the stay to the front of the mast, out of the way for tacking the headsail. All of that is more trouble than a day sailor or racer would want, but it makes sense for a cruiser because it offers power tuning normally not available on a swept spreader rig, which normally has to live with one tuning settup, that being low power. The advantage of the running baby stay over diagonals to hold the spreaders is that it allows setting the power on both sails, whereas diagonals only allow one tuning settup for the main, which would have to be low power. I'm not too savvy about the pure definition of B&R rig... I tend to classify rigs which did away with the forward lowers by using radical raked spreaders as belonging to the B&R rig family or calling them modified B&R's.
A backstay tensioner is not normally used with swept spreaders because pulling the mast truck aft loosens the uppers and the uppers are bearing forward pressure at the spreaders. The forward pressure is necessary because of no forward lowers. As Alan infers, unless diagonals are used to load the spreaders, a backstay tensioner while firming up the headstay and depowering the headsail, would power up the main with not much gained. A work around to enable backstay tensioner use beside diagonals is a baby stay to hold the middle of the mast forward when the backstay tensioner is engaged. On my C250 used primarily for cruising, there is no place or space for a standing rig baby stay so used is a running rig baby stay. It is a low stretch line from the spreaders through a block at the stem and back to a sheet winch. It uses a bungee which drops from the spreaders to a mast base turning block and forward to the line which serves as an auto retract line on the stay... in other words, when the running baby stay is released, the bungee retracts the stay to the front of the mast, out of the way for tacking the headsail. All of that is more trouble than a day sailor or racer would want, but it makes sense for a cruiser because it offers power tuning normally not available on a swept spreader rig, which normally has to live with one tuning settup, that being low power. The advantage of the running baby stay over diagonals to hold the spreaders is that it allows setting the power on both sails, whereas diagonals only allow one tuning settup for the main, which would have to be low power. I'm not too savvy about the pure definition of B&R rig... I tend to classify rigs which did away with the forward lowers by using radical raked spreaders as belonging to the B&R rig family or calling them modified B&R's.
We have a new Hunter 306 and it has no backstay at all since it has a B & R rig. My understanding of the definition of the B&R rig includes the fact that it never has a backstay, and the reason is that the severely swept back spreaders, with their shrouds, make a triangle structure with the mast. Everyone knows you can't distort a triangle without huge problems. In addition, the main is a very large roach sail, and a backstay would be incompatible with a main's large roach. The Mast has a fixed amount of bend tuned into it and therefore mast bend is not a variable on a B & R rig. So we just don't deal with mast bend on a Hunter B&R rig.
B and R Rig
In the late 80's Hunter introduced the B&R rig on production boats. It was on the 28.5, and the Legend series boats. The 80's version had single backstays that split to 2 mounting points on the transom. Mine was adjustable but not all of them were. There was a triangle with 3 sheaves just below the split in the backstay. Two of the sheaves were over the "legs" of the backstay and a 4:1 purchase block arrangement attached next to the backstay mount on one side, went up and through the 3rd sheave and back down to the other side of the transon. As the adjustment line was hauled in the 3-sheave triangle was pulled down pulling the 2 "legs" of the backstay together and applying tension to the backstay. Hunter abandoned the B&R for a few years and re-introduced it in the mid 90's as a backstayless rig that would allow big roachy mains. Tom
In the late 80's Hunter introduced the B&R rig on production boats. It was on the 28.5, and the Legend series boats. The 80's version had single backstays that split to 2 mounting points on the transom. Mine was adjustable but not all of them were. There was a triangle with 3 sheaves just below the split in the backstay. Two of the sheaves were over the "legs" of the backstay and a 4:1 purchase block arrangement attached next to the backstay mount on one side, went up and through the 3rd sheave and back down to the other side of the transon. As the adjustment line was hauled in the 3-sheave triangle was pulled down pulling the 2 "legs" of the backstay together and applying tension to the backstay. Hunter abandoned the B&R for a few years and re-introduced it in the mid 90's as a backstayless rig that would allow big roachy mains. Tom
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