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Old 22-07-2009, 14:30   #1
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Leeboards ?

I just started sailing after several false starts here recently, and that in a Snark! I am having a ball and learning.

I am converting one of the little plastic bass boats to sail with a small rig so the grandson's can go out with me on something stable that fits in the back of the truck. I have the latteen rig off the Snark set up and a rudder mounted on a board that clamps to the trolling motor mount. I was hoping the straight sides of the cat type hull would make it so that it would work okay without dagger or lee boards. No such luck on the trial run. Back and forth at best steadily being blown down wind. Luckily, there is a ramp on the down wind side where I was headed also!
Two possibilities without causing any damage to the hull. It has 3/4 inch aluminum pipe handles built into the sides at in the middle.
Option one, I can drop nine inch leeboards, on each side off the carry handles and I have plexiglass to do that. They can be made so that they pivot back up into the boat for beaching, hauling, and such. Are nine inch wide boards on each side enough for the flat bottomed cat type hull? If so, how deep to take them?
Option two, There is a second trolling motor mount on the front of the boat. Would a second rudder linked into the rear rudder by push cable act as a dagger board/keel? Would a fixed board at the forward position serve any purpose?
The boat is only 9 feet long and 46 inches wide. The two "pontoons" are flat bottomed with straight sides and the boat rides pretty high. The mast would snap before it could flip it without help with me in it. Safety with the little ones on the local lakes is the goal, not speed. Fishing maybe. Fun on local lakes is main purpose.
Thanks in advance!
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Old 23-07-2009, 04:40   #2
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I think you'd be better off with the first option, which puts the leeboards nearer to the center of effort of the boat. You'll have to experiment with the amount of surface area needed to get the thing actually sailing vs. simply floating downwind.
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Old 23-07-2009, 08:43   #3
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Yep, Hud's right on this one. My guess is you'll need a fairly longish board at 9" wide - I'd start about 36" long (I'm assuming you'll have about 12" out of the water, so really your effective leeboard is only 24" x 9") If it's possible to make the board a bit wider - 10-12" - that might help too. You can always make it shorter, so try even longer lengths first.

For simplicity while experimenting, don't worry about making them pivot. You should be able to just drill a hole near the top to tie a lanyard (so you don't lose it overboard), and just hold it in place while making test sails. If you attach a small wedge (to the boat, or the after edge of the leeboard above the water) so it has a slight 'toe-in' then once the boat is moving the water pressure will hold the leeboard in place. (Plus the leeboard will be a bit more effective as a foil, even though performance isn't a priority.)
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Old 23-07-2009, 09:13   #4
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I am looking at 9 inches wide by about 17 inches below the bottom of the hull on each side on the boards.
The forward board or rudder idea would be the easier of the two, since I have another fairly large for this job aluminum rudder already here. With only 9 feet between the two large rudders, side slip should not be a problem, or I don't think it should be a problem. I don't know about the steering issue tho.
The usual steering situation puts the pivot, the daggerboard/centerboard/leeboard/keel in the center of the boat where the rudder swings the boat around that central pivot. With a large board up front, instead of pivoting, steering would be more of a swing type of turn with the back of the boat actually being the part to move. That is unless both were live anyway.
I bought a piece of aluminum pipe last night that fits under the two hand rails, and PVC pieces that slide over the pipe. I can do a two pipe set up with the lee boards pinned in place on the end of the two pipes trapped against the side of the boat. I would have to do minor bending of the plexiglass to make it look better, but I have a heat gun.
The good. The boards would be fixed and pretty effective I think. It is easy to do. The bad. They will be fixed. The boat will need to be in at least 25 inches of water or so before rigging the boards. That isn't as big a problem as it could be, since the rear rudder is not a pivoting type and needs about 20 or so for me to put it on anyway. That way the boat has to be rowed out a bit and then set up. It would have to have the boards and the rudder removed for beaching. Eventually, the rudder will be changed to a pivoting design so it doesn't cause problems. The boards could also be modified to a pivoting type, but then we are no longer talking quick and easy. Both boards would be down all the time.
The original idea of using U bolts to clamp the plexiglass to the side hand rails, pivoting them down against the side of the boat and latching them there is easier by a fair margin as far as building. They would still both be down most of the time, because to pivot the windward up and out of the water would put it sticking out to the side like a wing. Or straight up, or folded back inside the boat. One looks really strange and is actually dangerous to anything I would pass too closely. One position stops the sail from turning and looks wierd. The other is in the boat in the way. Still looks like a pain.
The two pipes in the fixed design would be across the middle of the boat. The pivoting design would have at least one board folded into the middle of the boat anytime you had one or both up.
What images I found online were all of heavy metal rimmed designs off older wooden boats. They used a single pivot with the boards rotating up against the side of the boat. Most had a support channel built into the side of the boat that they slid into as they pivoted down. Looking at those designs, to implement one of them properly would require permanant modifications to the boat. As it is now, I take five screws out and the mast platform lifts out of the little boat, converting it back to the little fishing boat it was designed as.
A third option is to make them so that they drop over the the hand rails and are latched down somehow.
Thanks for the feedback! I had trouble going to sleep last night thinking about this little problem. I may mill a channel in a couple of pieces of wood and make up a pair of drop on boards today and then go see how well it works. I may also put the other rudder on a board and experiment to see what happens with it out front.
Maybe the best option is to build two easily removed fixtures to hold a more standard type dagger board that is simple to remove, adjust, and mess with.
Don't ya hate it when after some serious thinking about a problem, you have more questions than when you started, and no real answers yet!
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Old 23-07-2009, 10:25   #5
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The plexiglass is pretty thin to be attempting to creat an effective foil with unless I laminate two layers together. That is the plan once the actual design is set. The deepest part of the area under the handles on the sides is 9 inches wide. I could go out to about 12 inches wide if I used a drop on design that doesn't need to be able to pivot around the handle. The center seam on the hull is half way down the side. The board will have to be bent slightly to go over that and then straight down. I figured to use a rubber bumper to cover the lip of the seam for the board to rest against when under load. I had purchased small turnbuckles with a hook to latch the boards down against side of the boat and against that rubber strip.
Guess milling a piece of wood to drop over the handle and then using a strong bungie cord would do the same thing.
Anyway, thanks for the ideas!
Warning! Tis is an old outdoor puddle boat that has been well used and little loved
It is 17 inches from the bar to the bottom of the boat.



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Old 23-07-2009, 12:33   #6
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Here's How I'd Approach It

  1. Mount two permanent pieces of rail hardware of some type on each of those handholds, that have flanges that stick out enough to drill a hole in, if they don't already come pre-drilled.
  2. Attach a piece of over-sized angled aluminum channel along the top of each board, such that the channel covers the top and falls down the outside face of the board, leaving the "top" of the channel to protrude a couple of inches inboard, toward the gunwale of the boat. (The size of the channel will need to be at least 1 1/2" longer than the thickness of the finished leeboard, to provide a surface to be drilled).
  3. Drill holes in the top surface of the channels. Secure a piece of additional material (wood, alum.) to the channel that will span the distance between the outer edge of the gunwale and the rail clamps. Drill holes at the inboard end of this extention to mate the leeboard assembly to the rail clamps.
  4. Use large bolts, washers & wing nuts to attach the leeboard assemblies to the flanges.
When in use, the working (lee) board will be held against the side of the boat; the lazy (weather) board may pull away, and depending on the tightness of the mounting collars on the handhold, rotate the rail clamps. But the board should lever it back on the next tack.

When disassembled, all you will have left on the boat will be the rail clamps.

Good Luck,
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Old 23-07-2009, 12:51   #7
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Thanks for the response.
I am considering cantilevering them under the handrail this morning. I can use the heat gun to mold them to the shape of the boat out to the seam line within reason. If I also bend the end up, the boards will only fit under the rail if someone flips them above horizontal. Once in and lowered, they would not be able to be removed unless lifted above horizontal again. That leaves them free as you described. The windward board could actually be removed if needed for an expected long run without tacking. Not really likely with this boat very often! Not a lot of really big water around!
If I have enough aluminum, I may do pockets that would allow for swinging boards that would not break in the future if this works out.
Anyway, time to go playing the garage again!
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Old 23-07-2009, 15:29   #8
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That is today's idea getting ready to be tested. No clean up or even the protective coating removed yet. The edges are not even smoothed yet. If it works, then I will add a 12 inch wooden strip to the top to effectively lock the board into the slot at most angles. I still have not cut the depth yet. I think I am going to cut them to 20 inches below bottom of hull. The plastic is not stiff enough for general use, but it should be good enough for testing with two of them on the boat. They will need to be stiffer. I have rubber bumpers where they cross the seam, but they are unsupported below that. The top could also have a couple of thumb screws and conduit brackets added so that it actually clamped to the bar to keep slap down.
Will report back after the test tomorrow likely.
Thanks for the input! The first prototype answer is almost never the last prototype!
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Old 23-07-2009, 18:52   #9
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This will be a fun experiment. What percentage of the hull is forward of your leeboard and what percent after your leeboard? It should be just a bit forward of your center of lateral resistance. Once you've got the right shape and depth then to make them swing up would be so much better. That way you can get near shore easily without going aground.
I had a Naples Sabot with two leeboards. The lazy one got swung out of the way. They were shaped like rudders. Total length is 40" and from the hole at the top where it pivots is about 36". That would put the pivot at the top of the gunwhale. There was a special bronze fitting the fit the leeboards and I had two where most Sabots just had one. The Sabot was an 8 ft sailing pram dinghy.
24 years after selling the Sabot I still have the leeboards. Would you be interested in a photo and measurements?
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Old 23-07-2009, 19:08   #10
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Very elegant approach. I hope this works for you.
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Old 23-07-2009, 19:37   #11
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Thank you very much.
The boards are almost perfect center front to back. That is why the front board/rudder was considered. The mast is as far forward as I could get it. That puts the boards 28.5 inches behind the center of the mast. They are nine inches wide and extend 20 inches below the hull. I did cut the corners of the tips off, but other than that, they are still not shaped at all. If it works, I have some cloth out in the garage, I will shape the bendy plastic boards and then wrap them in glass. I drilled a corner on each, and made up a leash that goes around the board above and below the bar and goes around the bar at the ends. Likely not needed, but I will not lose one of them right off anyway!
The rig is far from perfect, but it lets me experiment with ease. I will have to change it a little over time. The lower spar swings pretty low over the boat.
Actually, if it works, I will likely just build a small rig just for this boat like the Snark rig. I need a little taller mast and was going to use a little longer top spar and a little shorter lower spar to better match the boat. If I get that far anyway.
I was shocked at just how well the little Lateen rig works on the Snark. I can't get it to sail a very high angle, but I am a beginner. I am sure there is more in there than I have found yet.
I guess the bottom line is that I am having fun! At my age, the pure lean over the side and try to steer up to cut the power while hanging onto the sheet stubbornly refusing to let any out until one gunwale is under water, you pick up half a boat of water, and then you finally let out and break the run off by turning down wind, is about as much fun as I have had in a while! I fit in a Snark like it is a wide kayak!
This little boat is going to be for times when Paw Paw can't do that cause one of the grands is along!!

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Old 24-07-2009, 12:45   #12
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While sailing to weather and you let go the tiller does the boat want to turn up into the wind, "head up" or "fall off" steer away from the wind? If you have to apply a lot of pressure to the tiller to get a little bit to weather then you might have to change your sail rig location or rig type or move your leeboards a bit fore or aft. Lateen rigs, like Sunfish have a center of effort a bit more aft than a marconi rig like the Laser or Walker Bay.
In a small boat, getting your weight fore and aft makes a big difference too. Especially when skipper weighs 200 plus pounds.
You'll be having lots of fun with this one.
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Old 24-07-2009, 12:49   #13
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Here's one I put together from scratch along with balancing the rig and placing, in this case a daggerboard, but the hull was originally designed for leeboards.
JohnL
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Old 24-07-2009, 16:28   #14
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Well, I got enough wind to find out that it works, but not enough to decide how well.

Beautiful little boat by the way! Certainly a lot more sail that I am using! I used my sail set about a foot higher today and the comfort level is much improved. Thanks for the encouragement!

First off, the windward board has to come out. As it is, it floats up and you might as well be pulling a small skier on the windward side. I tied the leashes without wrapping and pulled the windward board as soon as I tacked. Luckily, they pull out the top quite easily for changing.
Second, the boards are big enough I guess because when the wind blows, the boat moves on out pretty good, and accelerates well. Not sure about possible speed yet because the wind would never play nice long enough to find out. Too good for the way the boards are now tho on a couple of puffs. The drag will actually pull the boards to the rear with some force. Knife edging them will help some over the rough sawn edge on them now. I am going to have to put a board on the top like the top line on a capital T to keep them from kicking back when the boat starts to move. If this doesn't work, I will machine a piece with a slot that I will epoxy where the rubber bumper strip is now. I boards will have to be slid thru it when being installed. Not a great biggy to do if I have to, and it will not interfere with the regular usage of the boat. That pretty much would even allow you to pull them up some if you wanted when you were not trying to beat upwind.

I never did get enough time with a decent wind to decide how balanced it is. Moving me around makes too much difference like you mentioned. Just an impression, but I believe the little catamaran hull on this boat is going to point up better than the snark does. It is also pretty stable. It is no where near as peppy. That opinion may change if I ever get it out in good steady wind and see just how fast it will go.
Question. A plate riveted and epoxied to the seam flange. Aluminum or Stainless? The board will be inserted downwards thru a slot in it after going under the bar to fix the boards up and down angle along with the front to back.
On shaping. On a leeboard, Do I want to bevel from the inside edge outwards only shaping the inside edge to pull the foil towards the center of the boat? or do I want to do both sides and attempt to keep them running straight as possible? Does adding a bracket to hold them more steady and in one position change that answer? If the thin bendy boards work pretty well, would you still wrap them or laminate on a piece of aluminum to stiffen them up? Will it make a bigger difference in heavier winds maybe? In heavier winds, adding the side brackets will allow both boards to be run both ways if needed.

I am leaning towards cutting brackets, putting them over the boards to help position properly, and epoxying them down. Then going back and riviting them thru the seam overlap just for safety. That and T boards wider than the boards on top to help retain them and hold them straight should just about finish the construction of usable leeboards. I am not sure with the thin bendy boards that anything beyond knifing the forward edges and smoothing the other edges down is worth it. Is there enough there to make it worth going back and laminating or wrapping the boards to allow them to be shaped into true wing shapes?

Thanks to all who responded with ideas or encouragement! It works well enough that when the wind comes on, it steps out like you turned on a trolling motor. If it points up as well as it seem like it was today, I think I am going to like this set up! It definately needs more wind than the Snark, but the Snark isn't any fun in those kinds of wind anyway.
I am rambling, so time to shut up for a while!
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Old 27-07-2009, 14:59   #15
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The experiment is on hold until I get the yard repaired on the rig. I stuck the yard in the mud and broke it Saturday. I am going to fill the replacement with foam to make it a little tougher!
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