Making new style rudder for old style boat


Active Member
Thread starter #61
Those old tillers with those brass straps would flex so much in a breeze.
Hi Charles,

I generally sail in winds up to 15 knots and, while I am sure there is some flex, I have never noticed it. The length of strap that is unsupported by the either the tiller or the rudder head is quite small, so it doesn't seem to have a lot room to bend. I am sure the older one without the solid rudder head bends more, but even with that one I never noticed a problem.

When I sail, I am always thinking about the rudder load and tiller angle. I focus on keeping the rudder load to a minimum and the tiller straight. If the rudder loads up and/or it stalls I am dragging it sideways through the water, I sheet out and try to figure out what I am doing wrong (e.g. boat heel, sail trim, fore/aft gooseneck adjustment).
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Active Member
Thread starter #62
Hello fellow Sunfishers,

The next step was to attach the rudder hardware to the rudder. I waited a couple of weeks for the varnish to harden up so that when I slide the hardware on, they would not scrape off the varnish too badly.

During the epoxy/glass part of the process, the holes had been filled with epoxy so they needed to be drilled out. Once that was done, I ran the screws through, put the nuts on tight and then used a hacksaw to cut the screws to length. I then filed the screw ends flat and later backed them out and beveled them very slightly with a hand powered grinding wheel.

At some point, I will wet sand the whole thing again, but for now the rudder is done.



Active Member
Thread starter #63
Hello fellow Sunfishers,

I attached the tiller to the rudder a couple of weeks ago, and the tiller was just sticking way up in the air (Picture #1). To correct the height (i.e. lower) I used a dado stack and trimmed the underside of the rudder. After epoxying the trimmed out section, I then glued (spray adhesive) a piece of 1/16th" cork to the underside as a cushion. I then, drum roll please, actually went sailing with it. Unfortunately the cork wasn't quite thick enough, and the wing nut on the spring-plate put a nice gouge in the bottom. No matter. I removed the piece of cork and replaced it with a piece of leather. That seems to have corrected the problem for now, and the tiller height works well with the extension when holding the tiller in one hand, sheet in the other draping back to the hand holding the tiller.

There is also a picture that illustrates how I mounted the tiller extension connector.

Hope all of this helps someone in the future.



Active Member
Thread starter #64
Hello fellow Sunfishers,

I have been using the new rudder now for a few weeks. To be honest, I cannot tell much of a difference, certainly nowhere near the difference the newer daggerboard, but I have not tried sailing for 20 minutes and then going back to the older board. It seems to cut the water cleanly, no chatter, but I never spent a whole lot of time looking at the original, no chatter there either, so who knows? Hopefully I will have a chance to compare the two rudders before the season ends.

For anyone who wants to try this, here's what I learned.
  1. Laying out the lines on paper full scale allowed me to visualize what the board would be, and I spent a lot of time working on the angles.
  2. Likewise the full scale model in pine was of huge help in setting up all the cuts.
  3. Using the stack dado worked well for creating the rough foil shape. Controlling the cuts was difficult, and I used marks on the fence and board to know when to stop cutting. Here again the full size model was invaluable.
  4. I tried lots of tools after that to refine the shape. For me the most effective were a #2 hand plane, spoke shave, rasps, a #92 Stanley shoulder plane and sanding blocks. If you don't have all of those, then any hand plane that is sharp will likely do, along with a rasp and sanding blocks. It may just take longer.
  5. The leading edge I cut using a router table and a panel raising bit. I could have done it with just the hand plane and sandpaper, but I had the bit/cutter so why not?
  6. Final fairing was done with a rubber automotive sanding block. Be careful not to take off too much.
  7. I recommend using the garolite tubing for the screw holes for the rudder hardware. The extra $10 worth of tubing guarantees that the screws won't cut through the final finish and let water in. You don't want that after putting all the time into this project.
  8. I used a barrier coat with MAS epoxy. Most people like West, but I prefer MAS as the mixing ratio is 2::1 whereas West is 4::1. I'm not so clever, and its harder for me to mess up the 2::1 ratio. Whatever you use, make sure the surface is clean and you brush on a thin coat only.
  9. I covered the board in 4 ounce glass, but if I ever make another rudder I won't bother. Trying to get the glass to lay properly on a small object with multiple curves and some sharp angles was not easy, and I don't recommend it. Just be careful with rudder and you won't need that extra protection.

Again, I hope someone down the road finds all or part of this helpful.

If I ever get around to taking pictures of the rudder on a windy day, I will post again.



Well-Known Member
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.
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?

Fullscreen capture 10262017 63046 PM.bmp.jpg

The gudgeon is also a different design. Next July, I'll get close-up pictures.



Active Member
Factory's built these with cost of manufacturing in mind first. Good enough to perform adequately, cheap to manufacture. Cut, belt-sand the edges and finish. 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.
Good thing is it's dirt cheap to experiment with you own designs if you want to. Would like to see a original Sunfish racing against a couple different type clones for fun.