The propeller shaft hole will be drilled prior to sheeting the bottom
1. The propeller shaft hole will be drilled prior to sheeting the bottom. Two pieces of scrap plywood were screwed to the keel. Once the strut mounting holes were drilled, a stack of washers under each mounting hole was used to determine how much material had to be removed.
2. A jig was rigged up to flatten the strut mounting area. The router is run on two parallel lengths of angle iron.
3. Depth of cut is adjusted to remove enough material so that the strut sits flat on the plywood.
4. A block plane can now be used to finish the job.
A 1/8" masonite spacer was fabricated and slipped under the strut to simulate the thickness of two layers of fiberglass
1. A 1/8" masonite spacer was fabricated and slipped under the strut to simulate the thickness of two layers of fiberglass cloth which will eventually cover the hull. The strut was bolted into position and an 8' long piece of 1" round bar was fed through the strut to simulate the propeller shaft.
2. A guide block was loosely clamped to the keel. Click here to see how the guide was made.
3–4. Push the shaft through the guide block until it contacts the keel and mark the point. Shim the shaft until it's centered in the guide block and mark the holesaw entry point. Clamp the guide block.
5. Remove the shaft and insert the boring bar, coupler and holesaw into the guide block. Use an inclinometer to verify the shaft angle is correct before drilling.
This section describes how to build a boring bar which can be used to bore the propeller shaft hole.
1. The 1" boring bar consists of a 1" round bar, a slip-on connector and a standard holesaw fitted with a 1/2" x 18" extension bar.
2. The drive end of the tool is fitted with a 1/2" drive impact socket.
3. A 1" ID pipe sleeve is used to connect the 1" bar and the impact socket.
4. The coupler consists of a 1/2" drive 7/16" impact socket welded to a 1" ID pipe sleeve.
5. The pipe sleeve is drilled for a 1/4" x 2" through bolt.
6. To get the shaft hole started, a guide block was cut from a piece of 4"W x 4"H x 9"L stock. A 1-1/2" holesaw was used to drill a hole along the stock's length.
7. The piece was then cut on the bandsaw at a 12 degree angle to suit the propeller strut. To locate the point at which the holesaw will start cutting the plywood bottom, insert the holesaw into the big end of the block and push it in until the teeth are flush with the underside of the block. Transfer the mark to both sides of the block.
8. Insert an 8' long 1" bar through the strut. A scrap piece of 1/2" plywood is slipped under the strut to simulate the hull planking thickness. A piece of 1/8" masonite simulates the fiberglass thickness.
9. Push the bar through the guide block. Push until it contacts the keel and mark the point. Using shims, center the guide block on the shaft and mark the holesaw entry point. Clamp the guide block.
10. Remove the shaft and insert the boring bar, coupler and holesaw into the guide block. Use an inclinometer (angle finder) to verify the shaft angle is correct before drilling.
A fiberglass tube was inserted into the shaft hole
1. A fiberglass tube was inserted into the shaft hole. Click here to see how the tube was made.
2. This is a view from inside the boat. An 8' long shaft was fed through the strut and shaft hole. A 1" hole was drlled in frame #4 to position the shaft at 12 degrees.
3. A 1" ID x 1-5/8" OD rudder shaft collar inserted into each end of the tube will center the shaft in the tube until the epoxy cures.. When the boat is righted, the tube will be ground flush with the keel. Two laminations of fiberglass cloth will be applied to the keel before installing the shaft log.
This section describes how to cast a fiberglass tube which will be used as a lining for the propeller shaft hole.
1. A piece of 1" pipe is clamped in the vise. Wrap the pipe with a piece of cardboard sheet...
2. ... until you get the desired inside diameter.
3. Wrap the tube with duct tape.
4. Add a layer of waxed paper.
5. Laminate with two layers of fiberglass cloth. When fully wet out, wrap tightly with waxed paper and tape the whole tube to maintain even pressure on the tube.
6. The finished tube. Both the inside and outside surfaces are nice and smooth.
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