Building a KARA Hummer Layout Duck Boat #9: Applying the Plywood Deck Panels

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Blog entry by DustyMark posted 05-25-2015 03:17 PM 2446 reads 0 times favorited 2 comments Add to Favorites Watch
« Part 8: Anchor Pole Through-Hull Hole and Collar Part 9 of Building a KARA Hummer Layout Duck Boat series Part 10: Fiberglassing the Hull »


This is the stage where it really starts to look like a boat! With the the interior sealed and the final fitting of the anchor pole hole, collar, and sleeve complete, the deck can be installed. The sequence is similar to installing the hull panels with the added step of lining up the the through-deck hole for the anchor pole sleeve.

Fitting the Bow and Stern Deck Panels

The bow and stern deck panels are fastened around a curved rib and this causes the seams along the cockpit and where the panel lays across the forward rib to be thrown off of 90 degrees. It also causes the distance between the tabs over the side decks to be greater than the width of the cockpit.

My wife helped me bend the plywood around the cockpit support deck rib and we were able to mark the cuts we needed to make to adjust for the curve and the width between the tabs. The cut for the seam along the cockpit edge results in a curve. I made this as a series of straight cuts with my track saw. It may seem picky to cut this curve, but the rib is only 3/4” thick and if you don’t make the adjustment, the panel will be 1/4” from the cockpit in spots and that doesn’t give a good purchase for the nail into the rib.

After achieving a good fit along the cockpit edge, I drove screws in the deck rib and the bow to hold the deck plywood in place. Next, I marked the cuts that would center the side deck tabs over the outer ribs.

This photo shows the affect of the curve on the side deck tab that centers over the cockpit support deck rib.

While the deck panel was temporarily screwed in place, I traced the location of the deck support rib, anchor pole sleeve, and the gunnels along the perimeter. I used the location of the deck support rib to drill small holes that would ensure I drove the nails into the center of the rib. I cut the deck panel outside the line to make the panel easier to handle and ensure I could use my nail alignment tool.

Preparing to bore the hole for the anchor pole sleeve.

Hole alignment was good. It required slight filing on one side since it is on a curve and is no longer a perfect circle.

View of the dry fit panel. The screws are holding the panel in place at the cockpit edge and at the bow. NOTE: See if the first panel fits well on the other end. If so, trace it and save yourself a bunch of time on the other panel.

Fiberglassing Under the Deck Panels

I used 2.3 ounce fiberglass cloth to seal the underside of the deck panels. I applied the epoxy and waited about 8 hours for it to achieve a green cure. I applied a second coat of resin shortly before applying the panels.

View of the deck panels and the cockpit floor with the lightweight fiberglass cloth applied.

Applying the Deck Panels

The curves on the bow and stern deck panels were less severe than the hull panels. This made it easier to fasten these panels. NOTE: I continue to use thickened epoxy before fastening anything to the boat. I applied this mixture to the top of the frame parts before applying the plywood panel.

Driving the silicon bronze ring shank nails into the centers of the gunnels was much easier using this alignment tool. I only blew through slightly with one nail this time and that was just bad nailing as the nail ran crooked on me.

I applied the bow and stern deck panels first. I then fitted and made the final cuts for the side deck panels. NOTE: Wait to apply the second coat of epoxy on the side deck panels until after you’ve made these cuts!

View with all plywood panels applied, the main ribs cut to final depth, and the floor laid in place. NOTE: Don’t cut the main ribs to final depth for the floor until after you’ve applied the deck panels. The ribs will crack from the stress of the hull plywood trying to straighten itself out. The deck panels counter this stress.

Another view.

This is one low-profile, duck-ambush vessel!

Flush Trimming the Deck Panels

I decided that flush trimming the deck panels to within only 1/4” of the gunnel like I did with the hull panels left me with way too much hand work. This time I removed the final 1/4” by extending the bit to full depth and holding the router level with the ground. This gave the bearing a good surface to follow and removed all of the excess plywood. However, the danger is that if the router is leaned too far toward the center of the boat, you will begin to remove the gunnel. Take your time…the risk is worth it.

Rounding the Deck Panel Edge

The deck panel edge needs to be rounded to about a 1/4” radius so that the fiberglass for both the deck and the hull can wrap around it to the other side. Fiberglass won’t lay over a sharp angle. I used my rasp to round over the deck edge in the same way I rounded the edges of the hull panels.


In the next installment I’ll discuss fiberglassing the hull.

-- Mark, Minnesota

2 comments so far

View English's profile


512 posts in 897 days

#1 posted 05-25-2015 08:55 PM


Looking Good!! I bet That 2.3 oz cloth wets out easy. Great Idea for waterproofing the inside.

-- John, Suffolk Virgina

View DustyMark's profile


342 posts in 1490 days

#2 posted 05-25-2015 09:10 PM


Thanks! I think I used less epoxy with that light cloth than if I had brushed it on or spread it with a scraper straight. None of those areas are exposed to any traffic, so I thought it was a good choice. I glassed the hull today and will put each coat of resin on before it requires sanding. This is where the utility duck boat is a treat…less sanding.

-- Mark, Minnesota

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