June 2016,
We are almost ready to start fiberglassing the hull. Only a few more things I'l like to get done first. One of those is building the ballast keel stump. The is just leveling the bottom of the hull where the keel will bolt. I started by building a pattern of the external keel as it would be up against the hull. I laid this pattern in place on the hull and marked its outline on the hull. After removing the pattern I made sure that the hull within the outline athwartship was level. This required filling with more filler strake or planning existing hull off. The result is a level surface (athwartship) that I can start building up the keel stump. The next step is to take the keel pattern and transfer it to 3/4" marine plywood. This takes two pieces 8 feet long and we will call this a keel slice. This first layer or keel slice is fitted into place and bonded with epoxy and stainless staples. I perform a similar transfer and make another keel slice out of 3/4" marine plywood but this time I have shortened the forward piece around two inches. This is because the forward part of the keel sweeps back at a 45 degree angle and the aft part of the keel sweeps forward 3 degrees. I purchased the straightest 2X6X14 foot long piece of pine I could find and mount it edge up to the new keel slice making a ~16 foot long section that is rigid. Using a 6 foot level I place this keel slice in place and temporarily fasten it so that it is perfectly level. I actually left out a few steps; One is attaching the 14 foot 2X6 to the pattern first and setting it into place so that I could measure how much shorter the keel slice would be which is a function of the separation of the installed keel slice and the perfectly level pattern.
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| Leveling the second keel slice using the 2X6 and a 6 foot level. |
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| You can see the first keel slice which conforms to the hull along its length and the second above that is perfectly level. The space between the two slices of keel will be filled with plywood. |
The gaps between the two keel slices will be filled in with plywood. I am planning to use 3/4" plywood to fill as needed with square cuts and then the triangles that remain will be over filled with 1/4" plywood. This way, when I sand the edges smooth, I will only be sanding the 1/4" plywood and will have a reference every 1/4" of vertical measure. It's also a good way to use up that left over scrap 1/4" plywood from the hull construction without using a lot of the expensive 3/4" plywood and sanding most of it into dust. The top slice will then be permanently bonded to the keel finishing up the keel stump.
Later, when the boat is righted and the keel is ready to install, I'll bore the bolt holes through the keel stump first, align the keel and bore the holes through. I will then cut out the ballast section and send it to the foundry for casting and pouring. If I had a good lead supply, I would attempt this myself but lead is hard to come by these days. All the tire companies seem to be contracted to someone in some manner and won't deal with me which leaves me buying lead on the open market and that is just too expensive. So, I'll go with a cast iron keel for now. The material is free but the casting is expensive.
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| Here, I have added the 3/4" plywood fill for the keel stump. Notice that I still have the wedges to fill in front of the plywood. I plan to over fill these wedges with 1/4" plywood so when I plane the excess of the 1/4" plywood down I'll still have the corners of the 3/4" as a running reference of how much material I need to remove. More steps this way but less work and more accurate results (I hope). |
