I've read a lot, and visited several museums, and cannot recall ever finding out how a bowsprit works. Just read an article where they reduced it's length during a storm, which improved the sailing. The bobstay is connected in series to the forestay. This pushes the bowsprit back. What holds it from going back? How is it adjustable for length?
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Sprit Reduction?
I for one have not heard of a bowsprit that is anything other than permanent. Im not saying it doesnt exist, and i could figure out lots of ways to do it. But like you said, "The bobstay is connected in series to the forestay." If you were to move the bowsprit, then the forestay and bobstay would also have to be re-tensioned. Doesnt make sense, especially on the historical boats. Like Alan said, the bowsprit extends the boat out more forward to allow for a larger sail. If the weather kicks up and you want to reduce sail, what is usually done is that you drop the sail on the forestay and you have a smaller sail on an inner stay,which is usually parallel to the forestay but closer in toward the mast. Depending on the relative positioning of the mast and the size of the fore triangle, it would then be a cutter rig or a double headed sloop.
I for one have not heard of a bowsprit that is anything other than permanent. Im not saying it doesnt exist, and i could figure out lots of ways to do it. But like you said, "The bobstay is connected in series to the forestay." If you were to move the bowsprit, then the forestay and bobstay would also have to be re-tensioned. Doesnt make sense, especially on the historical boats. Like Alan said, the bowsprit extends the boat out more forward to allow for a larger sail. If the weather kicks up and you want to reduce sail, what is usually done is that you drop the sail on the forestay and you have a smaller sail on an inner stay,which is usually parallel to the forestay but closer in toward the mast. Depending on the relative positioning of the mast and the size of the fore triangle, it would then be a cutter rig or a double headed sloop.
Sprit Reduction?
My sprit is retractable (see pic).Most sportboats these days have retractable sprits, notably J Boats. A bobstay is only needed if the sprit is not made strong enough to support the load. My sprit can support about 2700#'s. An adjustable bobstay can easily be added if needed.
My sprit is retractable (see pic).Most sportboats these days have retractable sprits, notably J Boats. A bobstay is only needed if the sprit is not made strong enough to support the load. My sprit can support about 2700#'s. An adjustable bobstay can easily be added if needed.
See Woas' "Self-steering..."
Lee Woa's out-of-print book "Self-steering without a windvane" has an excellent chapter on his experiments with bowsprits. He made bowsprits for his small fiberglass cruiser and worked out some theory for how to rig them and how to use them. He seemed to feel that all the sails on the boat form a profile which tracks better as it is extended, in a way similar to how full keels track better than fin keels. I can't do justice to his discussion and the book can be had used on alibris.com or from a library willing to send it on interlibrary loan.
Lee Woa's out-of-print book "Self-steering without a windvane" has an excellent chapter on his experiments with bowsprits. He made bowsprits for his small fiberglass cruiser and worked out some theory for how to rig them and how to use them. He seemed to feel that all the sails on the boat form a profile which tracks better as it is extended, in a way similar to how full keels track better than fin keels. I can't do justice to his discussion and the book can be had used on alibris.com or from a library willing to send it on interlibrary loan.
Sorry, no sprit
David, sorry if I gave the impression that my boat is equipped with a bowsprit--I merely read about it. I do think the Woas book is the way to go for anyone with a smaller fiberglass boat that wants to play with them--he used a lot of simple and logical materials, including bamboo poles, and suggests a lot of ways to use the same simple poles for winging out jibs. And if you have a tiller you definitely want to have a look at his diagrams for how to get self-steering going...
David, sorry if I gave the impression that my boat is equipped with a bowsprit--I merely read about it. I do think the Woas book is the way to go for anyone with a smaller fiberglass boat that wants to play with them--he used a lot of simple and logical materials, including bamboo poles, and suggests a lot of ways to use the same simple poles for winging out jibs. And if you have a tiller you definitely want to have a look at his diagrams for how to get self-steering going...
Reefable bowsprits
The "shotgun" bowsprits that racers adopted several years ago have old roots. Back when mast heights were limited by the availability of strong, straight tree trunks, sail area, in light airs, was increased horizontally. One mechanism for this was a bowsprit extension that was simply hauled out by two gun tackles, similar to those used to position cannons at the gun ports.
The "shotgun" bowsprits that racers adopted several years ago have old roots. Back when mast heights were limited by the availability of strong, straight tree trunks, sail area, in light airs, was increased horizontally. One mechanism for this was a bowsprit extension that was simply hauled out by two gun tackles, similar to those used to position cannons at the gun ports.
Alan, how does this work?
Alan, what do you use as a sleeve on the bow to hold the pole in place? Your spinnaker pole cradle at the butt end is elegant. How much up force do you get on your pulpit apparatus? Any concerns about it pulling the pulpit off the boat? (We broke the back end of a retractable bowsprit pole box once and a couple of times I’d thought we were going to snap the carbon spar). What kind of PHRF hit did you take?
Alan, what do you use as a sleeve on the bow to hold the pole in place? Your spinnaker pole cradle at the butt end is elegant. How much up force do you get on your pulpit apparatus? Any concerns about it pulling the pulpit off the boat? (We broke the back end of a retractable bowsprit pole box once and a couple of times I’d thought we were going to snap the carbon spar). What kind of PHRF hit did you take?
Bowsprits and forestays
Traditional boats had permanent forestays that attach to the stem. The bowsprit was run out through the mooring bits and an iron collar at the stem. The bobstay could be of fixed length or adjustable. Jibs were set flying (no stay), what many people call jibs are properly called forestay sails (since they hank to the forestay). Later boats had permanent bowsprits and a jibstay was added to the end of the sprit, requiring a permanent bobstay. Forward of the jib a jib top was set flying or from a jib top stay if the sprit carried two stays. The forestay (from the stem) held the mast up, the other stays only set sails and the topmast may or may not depend on them for support.
Traditional boats had permanent forestays that attach to the stem. The bowsprit was run out through the mooring bits and an iron collar at the stem. The bobstay could be of fixed length or adjustable. Jibs were set flying (no stay), what many people call jibs are properly called forestay sails (since they hank to the forestay). Later boats had permanent bowsprits and a jibstay was added to the end of the sprit, requiring a permanent bobstay. Forward of the jib a jib top was set flying or from a jib top stay if the sprit carried two stays. The forestay (from the stem) held the mast up, the other stays only set sails and the topmast may or may not depend on them for support.
bowsprit
You guys raise some interesting questions that I had to figure out. How strong should the pole be?... how do you figure it? ...what should I use to hold the pole at the bow and how will it work? I decided to overbuild most of the pole to be able to handle most heavy weather. The block on the end of the pole that carries the adjustable tack line is designed as the weak link. If the worst happens, this block will fail first doing the least amount of damage. The outboard end of the pole can handle 2700# at a ninty degrees. The fulcrum mounted on the anchor roller plate rotates horizontally about 30*. The inboard end of the pole is a standard spinnaker pole fitting. The deck attachment is a standard pole deck fitting mounted on a stainlees plate to spread the load. When deployed the pole extends 5.5' beyond the bow and when retracted is completely out of the way. To deploy the pole, the trigger fitting on the inboard fitting is opened at the toerail attachment. The pole is slid forward and dropped onto the center pole fitting where the trigger automatically snaps shut. The tack line is lead through the tack block on the pole and back to the cockpit where it can be adjusted as needed.
You guys raise some interesting questions that I had to figure out. How strong should the pole be?... how do you figure it? ...what should I use to hold the pole at the bow and how will it work? I decided to overbuild most of the pole to be able to handle most heavy weather. The block on the end of the pole that carries the adjustable tack line is designed as the weak link. If the worst happens, this block will fail first doing the least amount of damage. The outboard end of the pole can handle 2700# at a ninty degrees. The fulcrum mounted on the anchor roller plate rotates horizontally about 30*. The inboard end of the pole is a standard spinnaker pole fitting. The deck attachment is a standard pole deck fitting mounted on a stainlees plate to spread the load. When deployed the pole extends 5.5' beyond the bow and when retracted is completely out of the way. To deploy the pole, the trigger fitting on the inboard fitting is opened at the toerail attachment. The pole is slid forward and dropped onto the center pole fitting where the trigger automatically snaps shut. The tack line is lead through the tack block on the pole and back to the cockpit where it can be adjusted as needed.
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