Deadwood and Keel

With the inside filleted and glassed, work moved back to the outside. We flipped the dinghy back upside-down. Not pictured is the removal of the wire ties. This was a quick two-person job: one person working with wire cutters and vise grips to pull the wire through, the other person with a soldering iron to heat the wire. With this process, we had no issues with any of the wires sticking in the hull.
Creative use of clamps allowed me to easily mark the curve of the hull on the deadwood. The inset shows a closeup of the wood block used to mark the curve.
With the deadwood cut, it is fitted in the proper location under the keel.
At this point, work moved on to the keel itself. I wanted the keel to be as close a fit to the hull as possible, for strength and lightness (less epoxy filler needed).
First, I marked off stations at regular spacing on the hull and keel. Next, I measured the angle of the hull at that location, and made up a set of angle templates on the computer.
From the angles, I calculated how deep to cut a V into the keel using my router table. With the deepest part of the V routed out, it was now simple to use a scraper and a file to make the sides of the V.
Moving back to the deadwood, you can see the screws I used to clamp the deadwood. This was test-fitting prior to epoxying the keel.
These two photos show the keel being clamped as well. In photo 2, note that the keel has been partially ripped horizontally on the bandsaw. This allowed the forward section to more easily conform to the curve of the hull. The amount of shifting between the two "plies" is shown by the blue tape on the side of the keel.

Epoxying the keel

First, I applied a layer of 9 oz fiberglass over the center join of the hull bottom. Holes were poked in the fiberglass to allow the clamping bolts to go through. Then, the keel was installed with thickened epoxy, and the bolts were tightened down.
The gray washers are 1/4" plywood covered in duct tape. Once the epoxy cured, they were fairly easy to remove from the screws. The screws themselves were stuck by the epoxy. To remove the screws, I heated them with a butane torch and then turned them out with a screwdriver (don't use your fingers!).
Also note the waxed paper visible in the photo 2. I taped it in place to catch the inevitable drips from the keel epoxy, making cleanup easier.
This is the view from inside the hull, showing the same washers as used on the outside.
Once the screws were removed, the screw holes were filled with wood and epoxy. I used toothpicks and cocktail forks, and trimmed them flush after the epoxy was dry.
The next step was to trim the excess overhangs of the keel at the bow and stern. These were rough-cut using a hand saw, and trimmed exactly using a Fein Multimaster at a later time.
One spot on the keel required a bit of filler before doing the final epoxy-coating of the dinghy prior to painting.

Keel Runner

For the keel runner, I bought two sections of 1/8" x 3/4" x 4' aluminum at Home Depot. In retrospect, I should have gone to a metals retailer and purchased a single piece of the correct length.
It would have been a waste to not use them, so I needed to find a way to join them. I used JB Weld to glue them together. My first attempt using a butt joint only survived about 10 seconds of handling. The second time using a scarf joint held up much better.
As with installing the keel, I marked off stations for the screws to attach the runner to the keel.
These holes were marked and drilled on the aluminum runner.
The holes were then drilled in situ, with the screws installed sequentially. The three clamps helped keep the runner in place and centered on the keel.
Once the dinghy was painted, the keel runner was permanently installed. These two photos show the runner and the screws ready for installation.
Here is the keel runner installed, as well as closeups of the bow, deadwood, and the aluminum scarf joint.

Outside Chines

Before glassing the outside chines, it was first necessary to fill any remaining voids at the plywood edges. I used epoxy with WEST 410 microlight fairing filler.
As with the inside seams, I used 9oz 3" fiberglass tape. I pre-cut all the fiberglass pieces and tacked them to the hull with spots of cyanoacrylate glue (CA glue; a common brand name is "Krazy Glue").
In photo 2 you can see the double layer of cloth at the widest part of the hull. I did this in anticipation of the fiberglass wearing through from launching. I also could have put a rub strip of metal or wood outside the hull. However, given that I don't normally plan to launch from a beach, I opted for the lighter and simpler solution.
One of the drawbacks of heavy fiberglass cloth is that it doesn't really want to sit on an outside corner -- it would rather be flat. To solve this, I adapted the technique of vacuum bagging to clamp the fiberglass while the epoxy cured.
Once the fiberglass was wet out, I covered it with a layer of pink nylon cloth. The epoxy doesn't stick to the nylon, and is able to pass through the nylon. Newsprint above the nylon absorbed any excess epoxy. Then, clear packing tape was used to apply pressure to the fiberglass.
Here you can see how nicely the fiberglass came out.
A fill coat of epoxy and microballoons was applied over the fiberglass, and then scraped down as far as possible to a smooth layer that would just hide the weave.

© 2015 Melissa Goudeseune