How do you think Mr. Hoyt would feel if he knew we were looking into or using his design on our models? Would he mind? :tapedshut :diablo:
not like we are selling it for profit…
tomo…taken to an extreme…
take a catameran…put the rig on the windward pontoon and then sail.
I doubt very much that you’d get the windward pontoon out of the water.
now take the rig and put on the leeward pontoon and sail. I’d bet your tipped over in no time.
when I get home I’ll make up a free body diagram and explain how that force is lesser in one direction than the other. which means on one tack, with an offset rig the boat will heel much easier. IE be tender, and on the other tack no so tender…
OK, that sounds somewhat reasonable, at least on a cat. But then a catamaran isn’t a monohull either. In the video Mr. Hoyt had, I didn’t 'see’ any of that happening. The worst thing he mentioned that that the offset boom might crowd people sitting on the rail on the boom side.
Since Andy already has a rig like this made, maybe he could settle that point…
Maybe Mr. Hoyt would get mad if we used his idea on our boats- some people are funny like that! A commercial builder could see our models and think the idea was free to anyone, even him.
Would anybody care to share the dimensions of their sail panel for this rig? I have two offset arms made and I will see if I can assemble this thing. From Andy’s picture, it looks to be about 10 x 15 inches (250x400mm)
thx
Offset 30mm 1/3rd in front of mast sail 300w x 400h
I will take some better photos tomorrow
Thanks a lot Andy.
I did not see any of that either…on the video. but what was his off set 12" with a 8’ beam… maybe,
Your talking about having to shift the offset on a footy 1/2" on a 6" beam…and I usualy have about 2 fingers(1 inch) between my sail foot and boom to allow for a nice curve. so now you move the offset a full inch… and now you have the weight of the sail and boom not acting on the center line of the boat you have an induced heel angle(unless you counter for it).
lets imagine you have a flat plate with a rod perpendicular sticking straight up int he center. like an upside down “T” if you exert a sidways force on the top of the rod you will be forcing one corner down while other corner lifts. like a boat wind exerts force on sail, boat heels. now take up upside down T and make it an L if you push on the top of the L to the left it will easily rotate counterclockwise and if you push hard enough it will fall over. now sit the L back up and push on the top of the L from the right. it won’t push over as easy. this is basically torque.
lets say in my drawing the distance form the pivot point(pink) to where the force (parallel to the horizon) is applied is 10feet and it takes 10 lbs to to rotate, or 100ftlbs…
now take the second drawing with the mast moved to the right of the pivot point lets say 5 feet. now you are not pushing perpendicular on the pivot point and you are pushing at an angle to the pivot point(63* relative to the horizon if it were perpendicular to the new). so the equation is. torque = (10lbs X sin 67)X 10ft result ing a torque of 89 ft lbs.
so by shifting the mast location and as such the applied force, you change the torque values…everything else being equal
Now in a boat you have a bunch of other forces. keel, water friction, windage, ect. BUT a sail boat the mast and keel are the levers (more or less) wind one way keel the other. once you change one dynamic, the others are affected.
here is a pic of the hoyt boat at rest at the dock. http://www.garryhoyt.com/sitebuildercontent/sitebuilderpictures/BR09.jpg you’ve already got a list to port and you are sitting on the dock…You already have a performance disadvantage on that tack… since you are already heeling to port…which means you had a corresponding advantage while on port tack…IN theory at least…
My head hurts now… I think its great idea for a rig…I think you could build one and have it balanced, at least on the scale of the footy…
of course I could just be overthinking this to the extreme…:zbeer:
Two fingers is probably too much belly on a Footy. You need that much on something much bigger, like a 1M. Plus the mast is 20-35% back from the luff, so that reduces the amount even more. So that brings the booms in to about 15mm or less, which is much better according to your theory. I will be using 10mm on my prototype.
Keep on thinking up stuff. We can either confirm it or figure out what really is going on. there are no bad ideas, just ideas that you learn from.
I agree.
So… to accomplish this offset booms idea, we need to figure out how much weight for the boom, gaff, and offset arms would be “too much” weight aloft. that would dictate what kinds of materials to make thing from.
I have 2mm wire, so I will try some offset arms made with wire. Wood, CF, and light plastics are others.
the only thing “extra” you have aloft is the gaff and any fitting for the offset.
sicne you already have the mast going up.
if anything you could shorten the mast since you are going to have a “fatter” sail, and that would help reduce weight aloft, or at the very least replace the lost weight with the gaff…
what about carbon tubes/rods very light and strong. or even square or rectangular carbon rods, if they are square or rectangular you may be able to notch them and use epoxy to fix them together…
or what about using a screw eye with a long shank as your offset and you can slide the gaff through the eye and then affix…
TomoHawk
I got the measurements slightly wrong it is 300w x 417h x 40 offset 4mm carbon tube & 5mm ally tube
reason for 40 is due to paneled sails.
Fwd edge of sail is a pocket round a 0.8mm stainless wire
rear is an adjustable sheet to tension top and bottom booms
Aft top and bottom corner of sail is adjustable through fuel tubes
Top brace was to help with strength following accident
hope this helps
I hardly noticed the top brace. I’m mostly concerned with being able to keep the booms from wobbling; to keep equal tension on luff & leech.
thx for the photos.
Wow- 4000 views! more than sailmaking. 
Are you making your rigs (swing rigs in this case) to fit only 1 boat, or do you expect a rig to be able to fit more than one? I have several Footies that I could put the new rig on (although not until spring) but each has a different kind of mast step or tube, unless I standardize them all.
I tend to use the same but why dont you make an adaptor?
here is my first attempt at a modified hoyt rig. sail and mast step are centered over center line of boat. mast has been offset…
sail is 300x260 fits the 12" storm rig rule. sails are paper for now.
mast and gaff/booms are carbon tubes with about 1" off set.
[LEFT]When you get a sail on it, put a fan to it and see how it reacts. See if it’s really good enough to be a ‘storm rig’ :devil3:
It looks like you got all the weight closer to the center like you wanted to.
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[LEFT]
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maybe I do like the hoyt rig and put in some reef points…
for a 12" rig it probably caries as much sail as my 24" swing rig…
with the 12" rig the wind speed is a bit lower that close to the water, plus you don’t have all that extra windage real high up acting as a lever arm trying to heal you over…
I have some light nylon, tonight I’ll put a sail on it and see how the weight compares to my other tall rigs… and dig out the fan.
Forecasted temps in the low 50’s on Saturday and Sunday, so I may be able to get it on the water…
Nice work Mark. Let us know how she sails.
I don’t know wether having the mast out in the air stream will slow you down or not. I do think that it will have an adverse effect on flow over the leeward side of the sail on starboard tack. Mr. Hoyt’s designs are intended to make single handed sailing practical for boats that are supposed to be handled by a crew. His aim is ease of use rather than outright speed. How a really small boat like a Footy will respond is anyone’s guess. If you pursue this rig type though don’t give up on it right away if it is not a winner right off. Experiments like these take time and ingenuity to refine.
I have some suggestions for your sail and its rigging. First, if you are going with a square sail shape like your paper cutout I would suggest that you rig the aft end of the gaff with an adjustable outhaul and leach control line. Being able to control the aft corner of the long head of the sail will let you adjust both camber and leach twist. I would also reinforce both the leading edge of the luff and the leach, in the case of the leach reinforcement this might help resist the sail just bagging out when the leach control line is loosened to impart twist. I would go for a more trapezoidal sail shape as the tensions from the sail will be absorbed by the gaff spar. A shorter spar would be stronger and less prone to distortion and also be lighter aloft.
Another thought is to make the upper gaff be able to rotate a few degrees in both directions from center. Controlling this rotation would let you adjust twist without being concerned about having the leach bag out.
Keep us informed of your progress.
Mr. Hoyt’s aim for the free-standing offset rig was to eliminate the drag of the igging wires, which could almost offset all the thrust the sail makes. The sail is then more efficient and you get more speed.
Being more manageable for single-handed sailing was a bonus.