Sunfish don't always sail in a forwards direction: backing in shallow water would increase the risk of rudder (and board) splitting.I've got a couple of questions for all of you Sunfish experts out there, the first of which is, "Why is the rudder bottom angled in such a way that the trailing edge is higher than the leading edge?" Have a look at the attached picture. The blue line in the picture shows how the trailing edge is shorter than what I would have thought. A couple of possibilities as to why the designers did this have crossed my mind:
1. It lessens the possibility of damage when hitting/scraping/beaching the bottom as the trailing edge is thinner and weaker than the leading edge.
2. When the boat is moving through the water the bow lifts such that the rudder bottom is parallel to the surface of the water.
My guess is that it's the first, but I am interested in what others think and if any knows for sure (i.e. in literature or builder told them directly).
The next question is whether it makes any sense to deviate from the design and have the trailing edge longer?
As always, thank you in advance for your thoughts.
wjejr do you sail where there are weeds?
You're going to put this rudder in WATER???Hello fellow Sunfishers,
Well, if it's worth doing, it's worth doing to excess. It's complete overkill, but I decided to use G10 tubing to line the gudgeioin mounting holes so that the threads of the screws never touch the wood. The theory is that the threads cannot scrape into the epoxy barrier coat I will put on later. If the screws cut through the barrier water could get under the epoxy and make a mess. Secondarily, it also prevents the hardware from compressing the mahogany. The screws would shear long before there would be compression of the G10. I had the G10 tubing lying around from another project, so no added expense; just a little more time. You can cut G10 with a regular saw blade, but here I used a diamond saw blade to cut it. You will see the pictures show that I use tape before drilling. This helps to prevent tearout (bottom) and is also easier to see the marks of where to drill (top). In the last picture you will see the G10 tubing in place. I sanded the edges of the tubing so that it forms a slight indentation where the epoxy can sit and soak in. Nex step will be to shape the rudder head, but that can't be done until the rudder head is mounted in it's permanent position.
In checking G10 (fiberglass tubes), I wondered if they made them in 2¼" OD? ('Didn't find any).Hi fellow Sunfishers. Its been so long, I had a hard time even finding my thread. At any rate, once the rudder was done, I had to make a new tiller since I wanted to keep the old tiller / rudder combination when I took my children sailing. That system has the original type wood extension which is shorter and easier to work with when I have a passenger. For the new tiller I again used G10 tubing for where the screws go through the bronze straps.
In checking G10 (fiberglass tubes), I wondered if they made them in 2¼" OD? ('Didn't find any).
For the sleeving of old holes, I cut sections out of golf club shafts. They're tapered—and stainless steel, so you can cut one or two sections that fit perfectly. My latest golf club acquisition is graphite, which is strong, rust-free, a good size, yet can compress a bit.
What use are golf clubs, anyway?
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Those old tillers with those brass straps would flex so much in a breeze.
A buddy has a pristine Viking [clone], whose rudder is different from others I have seen.I always give mine a airfoil shape just because. If you want to go all the way, leave the
trailing edge squared-off. With a rounded trailing edge there is flow separation about
two-thirds of the way towards the rear of the rudder on each side. With a square trailing
edge you get a vortex bubble that delays the separation. Hopefully, you will not get vibration.
There is one of those old bronze brackets on Ebay. Personally I'd put the money towards a new style bracket.
the Sunfish composite rudder is no different in shape than the wood rudder. The daggerboard is quite different however.If you look at the Sunfish racing rudder you'll see something
designed for performance based on hydrodynamics but it will cost you much more.
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A buddy has a pristine Viking [clone], whose rudder is different from others I have seen.
How does its overall shape, size, and edges fit with theories of hydrodynamic contours?
View attachment 24922
The gudgeon is also a different design. Next July, I'll get close-up pictures.
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