Accessories and Appendages

Even though the construction of the hull has been presented as a coherent linear story, the reality was not really like that. All sorts of things happened in between the orderly presentation in the pictures. Some of them were just life (work, family, pets, household repairs, a mild hurricane, a destructive tropical storm, etc.). Others were more directly related to the build.

In the latter category was the construction of the masts, spars and rudder. Those were built in parallel with the hull, mostly when the hull needed to cure. They were also worked on when I just couldn't face another couple of hours on my knees laying up fiberglass. That's one of the keys to a fast, efficient build - don't lose momentum. Always have something else to do if you can't, for whatever reason, work on the main project.

In my design, I decided to go with carbon fiber masts. This was because of the difficulty of finding good quality, straight-grained knot-free wood at reasonable prices (especially if you include shipping). Because of the gaff rig, there was the possibilty of the mast being struck by the gaff jaws at any point along its length. Carbon fiber, while almost magically stiff for its weight, is also brittle compared to wood and does not tolerate a compressive impact well. Because of this, I decided to use a hollow wooden core to increase the mast's impact resistance. I also went with a constant diameter mast for increased stiffness and ease of construction.

Click on any image below for a larger view

Hollow mast core

The core started out as a square cross-sectioned box, as on the right. After lots of sawdust, it had a circular cross section.

The wood is 3/4 inch BS1088 okoume plywood. With 13 plies, it's stiff and warp resistant even before it's assembled into a square. It's also lighter than any pine.

Joining core sections

The core was made of 8 foot lengths, but the masts are 12 and 14 feet long, so joints are mandatory. A 1x1 piece of pine 4 diameters long was fitted and glued into the core sections to provide support and bonding area. The hairline crack between the sections was filled with epoxy/woodflour putty and sanded smooth.

Completed foremast core

The main part of the mast is a constant 2 1/2 inches in diameter. The base, from the mast step until just above the mast partner, is 2 1/2 inches square. This locks the mast into place and prevents it from rotating. The upward curve is a photographic artifact.

The layers of carbon fiber and fiberglass will be applied in the Spring, once it turns back into epoxy weather.

The rudder blank

I decided, based on some hydrodynamic analyses that I read, to make the rudder thicker than what Bolger specified in his design. In theory, this should make the rudder more effective at lower speeds. I'll let you know.

The rudder blank is 3 layers thick - a 1/2 inch core with 3/4 inch faces. The central core is cut to take the 5/8 inch diameter type 316 seamless stainless steel tube that acts as the rudder shaft. The shaft is held in place with 1/4 inch stainless steel pins. The pins simply pass through both walls of the shaft, but are not otherwise attached. Once the assembly is bedded in epoxy/woodflour putty, it will be immobilized.

Since the shaft is thicker than the core, the faces need to have some material removed to accommodate the shaft.

Setting the shaft alignment

The level workbench is used to set up a jig that positions the shaft perpendicularly to the rudder blank surfaces.

Rudder blank test assembly

Final check to make sure that everything fits together properly.

Gluing the rudder blank

A thick layer of epoxy/woodflour putty was applied to all the internal surfaces with grooved putty knives. The openings for the shaft and pins were filled with putty before the metal was placed.

10 spring clamps held the edges in place and provided clamping pressure for the outer edge. 115 lbs of lead (made mostly of the future keel ballast) provided pressure for the central area.

A large amount of putty was squeezed out, indicating sufficient pressure. After a 2 day cure, the blank was ready for a hot date with Mr. Beltsander.

Copyright © 2011-2013 László I. Mórocz. All Rights Reserved.

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