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Go Back   SailNet Community > On Board > Boat Review and Purchase Forum > Sailboat Design and Construction
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  #11  
Old 11-28-2009
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There are much better uses for teak than something that's going to be in the water all the time, or glassed over anyway. I would worry about pine swelling.

I'd point out again that whatever you end up doing, removing the rudder between trips will help its longevity if that's practical (depends on the pintle/gudgeon design of course)
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  #12  
Old 11-28-2009
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Having done this myself, I would very much be in favor of laminating the pine into a rudder blank, shaping it properly and then glassing it with epoxy and cloth, then painting it. (I would also suggest that you consider laminating 3/4 AC plywood since the glue lines are very helpful in determining whether you have a fair curve) This should be an inexpensive and very durable way to go and no more maintenance than the aluminum.

I would be concerned that it would difficult to properly shape the aluminum so that you ended up with a symmetrical, fair shape that was not so thin on the edges that it was prone to easily be bent.

One problem with a wooden rudder is that it will tend to float up at speed and so you need to weight the end of the rudder to keep it submerged. The easy way to do this is to screw lead to the bottom of the rudder prior to glassing th blade. (The lead needs to weigh approximately 8-10% of the weight of the rudder blade).

Even aluminum is light enough that it will be pushed up at speed unless you have a hold down of some kind.

Jeff
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  #13  
Old 11-28-2009
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Google westsystem for some good info on how to produce a wood epoxy laminate.
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Old 11-28-2009
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Teak is renowned specifically because it does NOT tend to rot, warp or swell a lot in moisture-laden situations. Pine.... is not teak. In wide boards, it is especially prone to cupping, warping, and rotting. Wrapping it in fiberglass forestalls this, but is a lot of work. For your application and abilities, sticking with aluminum would seem to make the most sense. You can trim it to be moderately hydrodynamic, you won't have to ballast it to make it sink (half inch is pretty hefty) it's compatible with the rest of the steering system you've already (re)built, and you know how to work it. K.I.S.S.
** please note that original poster is experienced metalworker who has already redone tiller in aluminum.

Last edited by paulk; 11-28-2009 at 10:32 PM.
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Old 11-29-2009
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This is all very good info. Thanks for the input. I can appreciate some of the comments, such as getting a consistent foil shape out of the aluminum and the warpage issue on wide wood planks.

I did think about using a layer of 1/2 inch plywood in between the solid pine in order to help the overall strength.

I didn't think about the floating issue and have wondered about keeping such a system in the down position. I thought I would rig a rope to tie it down, and another to hoist the rudder up when needed. One concern is allowing the rudder to pivot up in the event I got into the shallows. It needs some sort of shear pin type setup-maybe a wooden shear pin that keeps the rudder down but would break if stressed by a sand bar. A weight sounds much better, no fussing with a pin.

I wish I lived near a marina so I could go look at some samples. I'll keep kicking this around until I settle on a good plan. No money to waste on experiments (unless they're free!) Flat.
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Old 02-15-2010
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What you could do is vacuum inpregnate the wood to increase its resistance to the water.
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Old 02-16-2010
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In my 15' daysailer the rudder is held down by a friction clutch on the thru bolt. Force it down by hand and if you hit bottom it just hinges back up.
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Old 02-17-2010
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David, I had to google vacuum impregnate but now I understand the process. Sounds like a good solution if you were set up for it.

Mechsmith - I'd be interested in your suggestion of a friction clutch. Could you take a picture?

What I have so far is the upper portion that ties to the transom is all aluminum, built from 1/4 in plate. The lower rudder is a laminate with a polyethelene core and aluminum shell. Its pretty high tech if I do say so myself.

The plan was to use a spring system to hold the rudder down and up. The only danger is that when the rudder is pulled up, I don't want it to come up so fast that it hits the helmsman in the nose.

I'll take a couple of pictures tonight and put them up.
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Old 02-17-2010
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Mine is all wood (3/4" marine plywood) but similar to yours . The rudder simply pivots in the frame. I have a Nyloc nut and bolt through the "sandwich" and a couple of coned washers to spread the load. You will need some rubberized washers between the metals. Use some industrial belting or the sides of an old tire for your friction washers. You will need four rubber washers and two metal ones. Then just tighten the nut as necessary to hold the rudder down. I simply reach over the transom and push it down. You may need a handle or something. No biggie!
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Old 02-18-2010
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Thanks Mechsmith, I suspected something similar to what you described. Should be no problem.

On the attached pictures you can see what I have so far. The lower section of the rudder is just out of the gluing stage, so I haven't done any shaping on it yet. You can see the layers glued together with 3M 5200, I'll radius the leading edge and taper the trailing edge so it is shaped like a foil.

Again, the layers are two 3/4" slabs of HDPE (I think) (I don't know the exact composition of it - so we'll call it "plastic"). The outter layers are 1/8" aluminum. I used the plastic for bulk and light weight and it won't swell when it gets wet. The aluminum is there for strength.

The upper section is all aluminum, 1/4" plate with 3/4" aluminum barstock for spacers.

The tiller is 1/2"x1 1/2" aluminum bar stock. I wrapped the end with 1/4" rope to make a grip. There is a pin that will pull out and allow the tiller to fold down for storage when I pull the rudder off. It will also fold up and lock so its out of the way during anchorage, etc.

Over and out! Flat.
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Rudder construction-photo_021710_002.jpg   Rudder construction-photo_021710_003.jpg   Rudder construction-photo_021710_006.jpg   Rudder construction-photo_021710_004.jpg   Rudder construction-photo_021710_005.jpg  

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