Photos of the DH Boat - 4

The DH Boat is a plywood construction. It was a design project by a friend of mine, to see how big a boat he could build out of 2 sheets of 4 ft. x 8 ft. plywood.

Details - Rudder.

Rudder in the lowered position. When sailing it would be in this position.

Rudder in the raised position. When launching, and when attaching the rudder before launching it would probably be in this position.

The after edge of the rudder. Shows that the lower part is sandwiched between two side parts so that it will pivot inside a wooden envelope which is the top part of the rudder.
This pivoting rudder may be the most intricate woodworking in the whole project.
You may build one that does not pivot, but it would be very difficult to launch the boat off a beach.

Detail to construct the Rudder. You will need a large diameter bolt for the pivot, Half inch thick and about 1.5 inches long. You will need 2 side pieces which can be made from 1/4 inch thick plywood. The middle (which is a spacer) and the blade should be of 1/2 inch thick plywood. Shape the front and back part of the blade so that it enters the water smoothly. Sand down the rounded head of the blade so that it will not bind too much when set into the rudder head.

The blade of the Rudder is
12 and 1/4 inches wide
and 38 and 1/2 inches long

The hole for pivoting is 33 inches up from the bottom edge.
The radius of the round end at the top is about 5 and 1/2 inches.

Note: the radius of the middle piece of the head of the rudder must be larger so it will be loose enough to move (not bind.)

The head of the Rudder is
12 and 3/4 inches fron to back - maximum measurement
(note the back edge slopes forward that the dimension
along the top is about 5 and 1/2 inches.)
(note 2 - there are 2 side pieces of the rudder head, They are identical.)

The dimension from the top to the bottom edge is 20 inches.
The hole for the pivot is 6 inches up from the bottom edge of the rudder head.

The middle piece of the rudder head is 20 inches from top to bottom.
The botom edge is only 2 and 3/8 inches wide, as the rest is cut away for the rudder blade to sit inside.
This piece is essentially a spacer so that the sides of the rudder head will not pinch the rudder blade.

The Gudgeon (or hinge) that attaches the rudder to the boat. This one was home made out of a stainless steel strap. There are 2 on the rudder and 2 on the transom of the boat.

The Transom with its gudgeons.

Detail of the rudder's mounting on the transom.
Normally the transom of the boat has the gudgeons (the part with the hole) and the rudder has pintles (a spike that looks like an L but turned so the spike points down and is attached to the rudder so that the spike can be put into the gudgeon's hole on the transom. With the normal arrangement the rudder can be lifted off the transom when you don't want it to be. Using 2 sets of gudgeons, with the ones on the boat spaced farther apart than the ones on the rudder, and having a long pin go down through both top and bottom the rudder is then solidly attached until you want to remove it by pulling the pin. Much like the hinge on a door.

The side of the boat showing the rudder and leeboard pivoted up. In this position one could launch off a beach or shallow area, row or pole out to deeper water and lower (more likely push down) the rudder and leeboard to sail.

The whole rudder and leeboard assemblies were made out of scrap 1/2 inch thick exterior plywood that was given to us at a house building site from their scrap pile. Some of the dimensions were dictated by the size of the pieces we had. They seem to work, but could probably be modified in size and shape and performance might not suffer.

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Click here to the Detail pictures - Leeboard - (DHBoatP3.htm).

Click here to the Detail pictures - Oars - (DHBoatP5.htm).

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