i have a dutchman and have converted to loos foot. no issues, just remember to tighten the out haul when dousing.
mike
mike
Converting Main Sail to loose foot
- Thread starter JRT
- Start date
Hey, John
How does your O'Day's new sail attach at the clew? And how's it working for you? I had Precision make me a loose-footed main with a slug at the clew. I don't like the slug; there's too much pressure on that small bearing surface for convenient outhaul adjustment. I've been thinking about cutting it off and rigging a clew strap, but maybe Sailrite's outhaul clew would work.
How does your O'Day's new sail attach at the clew? And how's it working for you? I had Precision make me a loose-footed main with a slug at the clew. I don't like the slug; there's too much pressure on that small bearing surface for convenient outhaul adjustment. I've been thinking about cutting it off and rigging a clew strap, but maybe Sailrite's outhaul clew would work.
Are you talking about an Oday mariner?
What kind of mechanical advantage does your outhaul provide?
If you want to adjust the outhaul manually (no winch), 4:1 would be the minimum. If you don’t have enough mech advantage, the wind pressure in the sail will be stronger than you are, no matter how the clew attaches to the boom.
I Havent seen your boom, but I doubt that the clew slide is the underlying problem, unless it’s the wrong shape or size, or unless the groove in the boom is in really bad condition. There are literally tens of thousands of small boats like yours, and bigger, with clew slides that work very easily, with 4:1 outhaul. For exmaple, catalina22s
On boats that originally came from the builder with a footed mainsail, the outhaul was “set and forget”. The builder didn’t expect you to adjust it while sailing, so they didn’t provide the capability to adjust it. If you switched from a foot mainsail to loose footed, you probably need to upgrade the outhaul.
Judy B
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Another option is to simply take some power off the main sail, adjust the out haul, then put the main back into the full power position.
Judy B:
Thanks for the info. I had considered that I might need to install more mechanical advantage. One of my objectives in owning the Mariner is having an inexpensive platform on which to learn how to maintain and modify a sailboat. The larger goal is to learn what I need/want/don't want on the bigger boat in the future. My modification strategy is to start out simple and cheap, learn what I can, then if needed, make another small mod until I get it the way I want it. You are right - the boat had a footed main and no outhaul control. So my first try at adding a 2:1 outhaul didn't work (except when the sail is luffing). Your post indicates that I should install a 4:1 system. I'll just go ahead and do that.
Thanks for the info. I had considered that I might need to install more mechanical advantage. One of my objectives in owning the Mariner is having an inexpensive platform on which to learn how to maintain and modify a sailboat. The larger goal is to learn what I need/want/don't want on the bigger boat in the future. My modification strategy is to start out simple and cheap, learn what I can, then if needed, make another small mod until I get it the way I want it. You are right - the boat had a footed main and no outhaul control. So my first try at adding a 2:1 outhaul didn't work (except when the sail is luffing). Your post indicates that I should install a 4:1 system. I'll just go ahead and do that.
Yep, that's what I do, but I don't like that. I can read a hundred articles and watch a thousand videos on sail trim, but I really don't get it until I feel my boat reacting to a single change. Pull on one string and see what happens. Keep pulling until I've gone too far. Adjusting more than one thing at a time, even if I try adjusting one of them back, doesn't work for my feeble mind.
I don't see many sailors changes their jib lead positions. I imagine that the hassle is not worth the perceived benefit. I installed controllable leads, and I change them all the time. It makes a sensible difference even on my small boat with a small jib.
You’re very welcome.
And remember to clean the track in the boom Spray some dry lube on the groove and the clew slide.
Pls come back and tell us how it works afterwards!
JudyB
bolt rope sails serve one purpose. one and done sail shape. The bolt rope completes a triangle plane. This connection of segments and the overlapping seams fixes the shape of the sail in all three dimensions. really all you can do to change sail shape at this point is bend the mast or adjust the boom up. Check out the design for the jib below. to make this jib i cut out a wood frame, stuff it with foam, then sand until the foam matches the wood. i then heat shrink gift plastic over the mold with a blow dryer. the resulting sail is a one piece 3D sail. the important part of the design is i can then tie off the three points with full tension. no matter the tension the shape is exaxtly as it was molded.
heres the rub. look at the bottom 1/3. The draft is terrible. the bottom third is wasting lift in the part where the wind is the least. look at the top third. the camber increases on the way up, when at higher wind speeds the angle of attack should be less. this was one of my early designs and not only was it a pain to make the molds, but the performance was terrible.
the other design, looks more like an airplane wing. the draft is proportional all the way up. This is a loose foot. This shape has the same angle of attack from top to bottom, but there is a problem. The shape is not dimensionally stable. infact, there is no shape once the sail is pulled off the mold. you just end up with a flat piece of sail with the foot a bit longer than what you started off with. in fact, even when put on a rig, you cant control the shape well, the max draft moves anywhere it wants to depending on the pressure. ive heard the shape is a "canternary". this shape still works great for RC models though and is super easy to design and cut out.
on a loose fitted main the sail, when all three corners are taught should have molded 3D shape, with crappy lift down low.
When the outhaul is lessened the foot draft will deepen, but at the expense of not knowing where the max draft will be at the foot. if one is looking for a boost in calm winds the extra curvature anywhere is better than no curvature at all.
Attachments
I would disagree with that, and if the ice ever goes away, I’ll certainly get pictures. The ability to control the draft with the outhaul and the traveler reduces the boom to little more than an attachment point.
You're talking about a hobie getaway mainsail now. notice how they have massive amounts of twist to "bleed" off the lack of dimensional stability, and then full battens everywhere. im sure there is a draft in those still. in other words, it probably doesnt lay completly flat on the ground, loose foot gives you more draft options.
I’m not talking about a Hobie, and I’m not even considering a theoretical model. I have a real sail that is not moulded, and is now a loose foot, that started life as a bolt rope, and removing the bolt rope from the boom added a huge amount of shape and control, and the recut should finish the deal.
I’m with Meriachee.
Most the content in BobbyFunn’s post isn’t applicable to real sails made of typical sailcloth or laminates, using typical construction details, and using professional design principles.
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When this project started, the bolt rope was removed and the sail flown. The slug turned out to be a pita, but the difference in the way the shape took, showed that the bottom 1/3 of the sail had a way better shape, and the boatspeed and how it was more upright could not be argued. The better sail shape was hampered by the bolt rope proper.
Now the rope has been removed. The modifications were done over the winter and it’s not time yet, so the results have yet to be seen, but I’m with Judy, this is not a million dollar molded concoction, it’s an off the shelf Dacron, and a cheap one at that.
Now the rope has been removed. The modifications were done over the winter and it’s not time yet, so the results have yet to be seen, but I’m with Judy, this is not a million dollar molded concoction, it’s an off the shelf Dacron, and a cheap one at that.
Total BS. high tech sails are absolutly molded. they start off with a platform that has been shaped to the final product. laminate is layed over the shape, next, fibers are layed in various directions, finalkt another laminate is sealed on top of that. the result is a fiber sandwich. when the final product is pulled off the mould the sail fibers and the laminate are in the shape of the mould.
I’m with Meriachee.
Most the content in BobbyFunn’s post isn’t applicable to real sails made of typical sailcloth or laminates, using typical construction details, and using professional design principles.
i tried this at home on a small scale to make my heat shrink sails stronger. the sails were so strong i couldnt get them to turn inside out on a tack. them suckers never flattened out.
the old school technique is to broadseam. same thing. if the sail is broadseamed it should be dimemsionally stable, since the broadseam pulls the fabric off the plane.
i guarantee if you suspended your main by three points say two trees and your truck hitch, you would see a beautiful moulded shape hanging down. thats the dimensinal stability that gives you repeateable sailing. thats from broadseaming. loose foot just lets you open the draft more, but somewhat randomly.
I sail a 170 at the local sailing club, but get to watch pros competing often. i sail with dacron, but cant use dacron for RC as it is too heavy. My RC sails used to be the pkadtic used to wrap easter baskets.
if you ever have a chance, listen to a f15 multihull jibe. OMG. That is a main....nothing like a dacron.