Building a KARA Hummer Layout Duck Boat #2: Assembling the Upper Frame

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Blog entry by DustyMark posted 05-12-2015 04:56 AM 13165 reads 1 time favorited 0 comments Add to Favorites Watch
« Part 1: Building the Lower Frame Part 2 of Building a KARA Hummer Layout Duck Boat series Part 3: Planing the Gunnels »


I let the epoxy cure on the lower frame for about 12 hours before proceeding with the upper frame. I dry assembled the parts with screws before gluing to ensure everything fit. I continue to use epoxy, thickened with colloidal silica to a mayonnaise consistency, to glue each joint in the boat.

I never figured out how the designer fastened the plywood to the gunnels. In the boats I’ve built in the past, the gunnels are planed to an angle that gives the deck or hull plywood a flat surface for a good nail and glue bond. I suspect that the plans assume the builder will just make the plywood meet at the edge and nail it in place with gaps at the gunnel. A lot of these boats are in use, so it obviously works. I’m not satisfied with that approach and decided to make changes as needed to allow for planing the gunnels for better glue-up.

I read that another builder added two supports between the cockpit support rib and the deck rib to strengthen the deck for walking on it. This seemed like a good modification and I did the same to my frame.


I did not like the lines of the cockpit deck support from the plans and the deck rib was 1/2” low which caused the deck to have a dip. This would have made it very difficult to bend and affix the 1/4” plywood deck. I made a new deck rib that was 4” tall instead of 3 1/2” tall. This eliminated the bothersome dip. I also redesigned the cockpit support deck rib to facilitate landing the plywood on the gunnels at a better angle.

Upper Frame

Assembly of the upper frame was pretty simple once I made new ribs. Even with all of the prep work, I had to use two different batches of glue due to the amount of time it took to assemble. The first batch would have cooked off before I was done.

A view of the upper frame before adding the extra supports.

Close-up of the cockpit deck support.

Deck supports installed. I splayed these at 10 degrees to follow the curve of the plywood more closely.

Close-up of side deck supports. I used a 13 degree angle for the side deck support cleats. This landed the plywood at a good angle on the gunnels.

Side view.

Front view.


In the next installment, I’ll discuss how I planed the gunnels.

-- Mark, Minnesota

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