Monday, May 26, 2008

Reinforcing the Keel

I'd been pondering for quite sometime the various options for building up the keels of my Tiki 26 to reinforce them for occasional intentional beachings and inevitable unintentional groundings. Most Tiki 26 builders add some kind of keel reinforcing strip, sacrificial wooden shoe, or strip of metal or PVC plastic. The problem with some of these add-on materials is they often requires screws penetrating into the glassed-over keel to hold them, or they are glued on with epoxy or bedding compound but can eventually work loose. The other problem is that it would be difficult to keep bottom paint on a metal or plastic surface, and difficult to fair it in to the rest of the hull for a smooth entry through the water.

To keep it simple, I decided to use 1708 fiberglass tape, a heavy biaxial fabric with a mat on the inner side. This thick tape, in the 6-inch width, holds a lot of resin and will add a very strong layer of protection to the keel. It may eventually wear down from abrasion, but that will take a long time, and it can be easily replaced. I don't plan on much beaching and when I do nose the boat up to the shore it will only be for brief visit as I always anchor off for any extended stay or if there is a sea running.

This tape is so thick it is necessary to first wet it out completely from the inside before applying it to the hull. I did this on some scrap plywood panels shown below. I also sanded, cleaned, and coated the keel area of the hull with wet epoxy before laying the tape on.

Here, you can see the 1708 tape in place on the keel. Since it reaches 3 inches up on either side of the keel, it provides additional strength all along the bottom, which could help if I ever find myself aground on a reef or rocks.

Fairing this stuff into the hull is quite a job. After laying down the tape strip and making sure it was completely wetted out with pure epoxy, I went back over it with a first layer of epoxy thickened with microballoons and silica. This was applied with a drywall knife, but is still thin enough to fill the weave well. As you can see, more epoxy putty will be needed. The next round will be thicker to build up a deep enough coating to sand it smooth.

I plan to go ahead and turn the port hull over again as well, to give it this same treatment. I will then fair and prime both hulls before proceeding with the decks and cabins.

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