I’ve been contemplating a change in the rigging for my sailboat Marjorie, currently stored on a trailer, under a tarp, in my backyard in Florida. I really like Marjorie’s ease in setting up and her handling underway, but there are a few things that I’m uncomfortable with. She has a great deal of weather helm when the full mainsail and jib are up. Also, she’s really tender, heeling over a great deal in anything over ten knots of wind. Granted, she only goes over about fifteen to twenty degrees and then stiffens up, but it’s disconcerting at how easy that initial heel is. In order to learn more about rigging, I’ve been reading the Complete Rigger’s Apprentice by Brian Toss. It’s a great book for the novice, with good descriptions of rigging details and so easy an explanation of the formulas involved that even with my poor understanding of math I can grasp the process, if not the theory. Though the book in no way would allow me to become a real rigger, it does allow me to understand the forces acting on the rigging, use the formulas to determine those forces and make informed decisions about rigging a small boat.
As designed, Marjorie is a fractional rig sloop; meaning that her forestay attaches to the mast about 3 ½ feet below the masthead and extends to the bow, rather than to a bowsprit. She has two shrouds set on either beam well aft of the mast step that attach at the same level as the forestay. The shrouds each have spreaders, but these don’t change the angle of the attachment at the mast. From the Rigger’s Apprentice I learned that since these spreaders aren’t normally under tension and don’t change the angle, they’re probably meant to counteract the deviation of the mast from compression load when the wind picks up.
When I began considering options I thought about Marjorie’s design. She was built by Southern Sails Inc. in 1981 as a cuddy cabin version of their Skipper 20. Both have the same hull, carry the same amount of sail area, but the Skipper 20 had a bowsprit, 100 pounds more ballast and 150 pounds more displacement. I suspect that the mainsail overpowers the tiller because the jib was moved 1 foot 3 inches aft on Marjorie. Also, because she’s lighter, but has the same sail area and mast height, the wind force acting on her is more pronounced against the righting motion of the keel.
So, how to correct this cheaply, because who knows if I’m right until I build something and try it out underway? Reducing the weather helm should be corrected by moving the jib forward to her original design length. Of course this means that I’ll need to build a bowsprit and get a new forestay, but more on that later. To reduce the amount of initial heel, I feel the best way is to bring the center of gravity of the mainsail down closer to the keel. If I can do this, then even though the sail area of the mainsail doesn’t change, the way it acts on the boat should. Lots and lots of reading later, the sail plan that would do this - and is most appealing to me visually - is a low aspect gaff rig.
Luckily I just happen to have plans for a gaff rig that has approximately the same sail area as Marjorie: the Weekender. The Weekender’s mainsail and jib are more or less the same sail area as my mainsail and jib and the length from the bowsprit to the mast step is about the same. Obviously, nothing else about the Weekender (a flat bottomed, plywood, homebuilt sharpie) is similar to Marjorie (a self-righting, fiberglass sloop).
The total re-fit would involve replacing the mast and boom with wooden spars, replacing the shrouds with new wire and deadeyes, adding a wooden bowsprit and chain bobstay, replacing the forestay and making a new mainsail. The directions to do all of this cheaply are contained in the Weekender plans, though they recommend using wire clips rather than wire splices for the shrouds and forestay.
Initially I had to determine the shroud and forestay size, because the Weekender uses four shrouds (two to a side) and I only wanted to use one per side. Using the Rigger’s Apprentice I was able to determine that the Transverse Rigging Load (strain on mast and spars at 30 degree heel) for my boat is approximately 6800 pounds with a safety factor added in. At least half that load will be taken by either shroud, so I could go as low as 3/16 inch wire rope which can handle 3700 pounds. But I want to use 1/4 inch wire rope because I’ll put a Molly Hogan splice and Liverpool Eye splice in each shroud, which will reduce the strength of the wire by approximately 30%. Additionally, I’ll increase the diameter of the deadeyes and change the diameter of the fiber lanyards from 1/4 inch nylon (breaking strength of 1700 pounds) to 3/8 inch nylon (breaking strength 3650 pounds).
Determining the length of the wire to use for the shrouds and forestay actually was the most complicated part of the planning process. I hate math, I always have, but luckily the Rigger’s Apprentice is very good at using easy equations and a scientific calculator. In order to get the length of the forestay, I needed to determine the angle from the mast to the forestay. This is accomplished by taking the base of the triangle formed by the mast and stay dividing it by the height of the mast at the forestay attachment, then taking the arctangent of the resulting number. The angle is 33 degrees. Given that angle, in order to get the length of the stay, I need to divide the base of the triangle by the sine of the above mentioned angle. In this example, I find that I need to make Marjorie’s forestay 15’ 1” without the turnbuckle.
The shroud length is similarly determined to be 13’ 3” without deadeyes and lanyards. Though I have to say that the calculations were more involved because the shrouds are set back from the mast step 2’ 5” and it took me awhile to figure out how to determine the appropriate base to use. Some may have noticed at this point that I keep mentioning that these are lengths without considering turnbuckles and lanyards. That works out ok because there’s supposed to be rake in the Weekender mast. Because Marjorie’s mast step is on the cabin top, adding a turnbuckle at the forestay will rake the mast aft, while still allowing 18 inches for the lanyards on the shrouds.
So all of this is complicated and if it’s ever going to get done, I have to do some of it here in NYC. I just happen to have a rigger’s vice (and a friendly rigger) nearby, so the shrouds and forestay are likely to be done over the fall. The deadeyes are complete, thanks to the help of the carpenter at work. The sail is probably going to take some time, but oddly enough except for the lofting, I can do most of the work in my apartment. I don’t have a TV and I’ll have lots of time when the sailing season stops.
As designed, Marjorie is a fractional rig sloop; meaning that her forestay attaches to the mast about 3 ½ feet below the masthead and extends to the bow, rather than to a bowsprit. She has two shrouds set on either beam well aft of the mast step that attach at the same level as the forestay. The shrouds each have spreaders, but these don’t change the angle of the attachment at the mast. From the Rigger’s Apprentice I learned that since these spreaders aren’t normally under tension and don’t change the angle, they’re probably meant to counteract the deviation of the mast from compression load when the wind picks up.
When I began considering options I thought about Marjorie’s design. She was built by Southern Sails Inc. in 1981 as a cuddy cabin version of their Skipper 20. Both have the same hull, carry the same amount of sail area, but the Skipper 20 had a bowsprit, 100 pounds more ballast and 150 pounds more displacement. I suspect that the mainsail overpowers the tiller because the jib was moved 1 foot 3 inches aft on Marjorie. Also, because she’s lighter, but has the same sail area and mast height, the wind force acting on her is more pronounced against the righting motion of the keel.So, how to correct this cheaply, because who knows if I’m right until I build something and try it out underway? Reducing the weather helm should be corrected by moving the jib forward to her original design length. Of course this means that I’ll need to build a bowsprit and get a new forestay, but more on that later. To reduce the amount of initial heel, I feel the best way is to bring the center of gravity of the mainsail down closer to the keel. If I can do this, then even though the sail area of the mainsail doesn’t change, the way it acts on the boat should. Lots and lots of reading later, the sail plan that would do this - and is most appealing to me visually - is a low aspect gaff rig.
Luckily I just happen to have plans for a gaff rig that has approximately the same sail area as Marjorie: the Weekender. The Weekender’s mainsail and jib are more or less the same sail area as my mainsail and jib and the length from the bowsprit to the mast step is about the same. Obviously, nothing else about the Weekender (a flat bottomed, plywood, homebuilt sharpie) is similar to Marjorie (a self-righting, fiberglass sloop).
The total re-fit would involve replacing the mast and boom with wooden spars, replacing the shrouds with new wire and deadeyes, adding a wooden bowsprit and chain bobstay, replacing the forestay and making a new mainsail. The directions to do all of this cheaply are contained in the Weekender plans, though they recommend using wire clips rather than wire splices for the shrouds and forestay.Initially I had to determine the shroud and forestay size, because the Weekender uses four shrouds (two to a side) and I only wanted to use one per side. Using the Rigger’s Apprentice I was able to determine that the Transverse Rigging Load (strain on mast and spars at 30 degree heel) for my boat is approximately 6800 pounds with a safety factor added in. At least half that load will be taken by either shroud, so I could go as low as 3/16 inch wire rope which can handle 3700 pounds. But I want to use 1/4 inch wire rope because I’ll put a Molly Hogan splice and Liverpool Eye splice in each shroud, which will reduce the strength of the wire by approximately 30%. Additionally, I’ll increase the diameter of the deadeyes and change the diameter of the fiber lanyards from 1/4 inch nylon (breaking strength of 1700 pounds) to 3/8 inch nylon (breaking strength 3650 pounds).
Determining the length of the wire to use for the shrouds and forestay actually was the most complicated part of the planning process. I hate math, I always have, but luckily the Rigger’s Apprentice is very good at using easy equations and a scientific calculator. In order to get the length of the forestay, I needed to determine the angle from the mast to the forestay. This is accomplished by taking the base of the triangle formed by the mast and stay dividing it by the height of the mast at the forestay attachment, then taking the arctangent of the resulting number. The angle is 33 degrees. Given that angle, in order to get the length of the stay, I need to divide the base of the triangle by the sine of the above mentioned angle. In this example, I find that I need to make Marjorie’s forestay 15’ 1” without the turnbuckle.The shroud length is similarly determined to be 13’ 3” without deadeyes and lanyards. Though I have to say that the calculations were more involved because the shrouds are set back from the mast step 2’ 5” and it took me awhile to figure out how to determine the appropriate base to use. Some may have noticed at this point that I keep mentioning that these are lengths without considering turnbuckles and lanyards. That works out ok because there’s supposed to be rake in the Weekender mast. Because Marjorie’s mast step is on the cabin top, adding a turnbuckle at the forestay will rake the mast aft, while still allowing 18 inches for the lanyards on the shrouds.
So all of this is complicated and if it’s ever going to get done, I have to do some of it here in NYC. I just happen to have a rigger’s vice (and a friendly rigger) nearby, so the shrouds and forestay are likely to be done over the fall. The deadeyes are complete, thanks to the help of the carpenter at work. The sail is probably going to take some time, but oddly enough except for the lofting, I can do most of the work in my apartment. I don’t have a TV and I’ll have lots of time when the sailing season stops.
I'll be curious to follow your progress. I would like to make this conversion on my production sloop.
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