Rudder, Tiller, Leeboard...
I was doing my home work at Jim Michalak's site regarding rudders and leeboards (more leeboard info) when I ran across his review of Ted Cary's idea about using nylon seat belt webbing in place of pintles and gudgeons. (The hardware that holds the rudder on.) Now I have a set of bronze hardware from Jamestown Distributors, but this method intrigued me. Mounting and removing the rudder should be easier. Though it takes a little time to make, the materials cost is negligible.
Here's Jim's sketch. His write up on
it is here.
And here's how I decided to modify
it. Ted also glued his webbing with epoxy. I'm going to try using PL Premium (of
course) but I'm also interested in some kind of mechanical hold that might let
you change the webbing if necessary. Here's one possibility.
This
is similar to the way canvas is held in directors chairs. A hole is drilled at
the bottom of the Kerf, and the webbing wraps around an 1/8" brass rod.
I'll let you know how the experiment turns out.
I started with a 10" piece of
2x6. I cut a 7/8" deep saw kerf down the center. The yellow dotted lines
show how I modified the design by tapering the insert. In instrument building
this trick is used to join necks to bodies. In theory when you insert it it will
snug it up against the transom.
This could all be done with a hand
saw, but I used the table saw. I don't own a taper jig. But here's an easy way
to cut a taper using a scrap of plywood. I set the saw to 25 degrees and clamped
the fence about 5 inches away. I ran a scrap of plywood throught the saw. I then
lined the cut edge of the ply up with marks I made on the BOTTOM of the wedge
stock. I stapled it in place with 1/2" staples and ran in through the
saw. I then pulled it off and stapled it to the other line. Works great.
Here's the wedge with the seatbelt
webbing trial fit in the saw kerf.
Here are the receivers trial clamped
to the transom.
I shortened the receivers so the
wedge is longer so I could tap it loose if it should get stuck. I've also
rounded the edges and sanded them some.
I laminated two 1/2" pieces to
make up my rudder and leeboards 1" thick. I used 1/2" on Featherwind,
but it sometimes seems a little flimsy and isn't very straight. It's also hard
to imagine standing on the leeboard to turn her over. So I'm beefing these up a
little. If you decide to use 1/2" I recommend laminating it from 1/4"
to prevent warping. (If you lack enough clamps you can use heavy weights and/or
dry wall screws to laminate these.)
I'd like to confess that I'm getting a little carried away with these sailing bits. The boards can be simply 1/2" ply with edges rounded and the mast can be a single 10' 2x4 left full 3.5" wide for the first 3 feet then tapered to 1.5" at the top. Round the edges and call it a day. It's mounted athwartship (1.5" ends pointing to the sides of the hull) so the most stress is carried where it's stiffest. This is what Dave Carnel calls for on his $200 sailboat Nutmeg. (a.k.a. Featherwind) It seems like "underkill" at first glance, but if you think about it, if you're in the kind of weather that will break a 2x4 maybe your sail should be down anyway. I'll actually be making a mast to these dimensions too, and fitting the hull with multiple mast step positions so I can test different rigs, and document them.
The
tiller is made from the triangle left over from the skeg. 3/4" x 3.5"
stock. I drilled a one inch hole in it, then sawed to the hole to form the slot
for the rudder head. Since the rudder stock in 1" thick and has been
rounded with a 1/2" radius router bit, it fits the slot perfectly. Very
satisfying. Could be left square though.
On
Featherwind I made the rudder and leeboard of 1/2" ply with the edge just
rounded. It works fine really. Though the leeboard vibrates at certain speeds. I
decided (for some crazy reason) to shape my blades this time. Rule of
thumb is tapered and rounded leading edge, thickest point about a third behind
the leading edge, and a smooth taper to a rounded trailing edge of maybe
1/4". (I did read one report of vibration of a foil being cured by the
trailing edge being square instead of round and beveled at about 30 degrees.) I
used a hand saw to score the rudder blade to make stock removal easier. I used
chisel, belt sander etc. to remove the stock. It was a pain.
When
I switched to my power planer it got a lot easier.
The plies show the topography of the
blade as you go.
Getting
closer.
Here's
the head of the rudder.
The
lee board is 12" x 48" x 1". An "ear" is cut in the top
corner to help raise and lower it, and to tell at what angle it is, at a
glance.