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Building Kayaks for the Grandkids #4: Making Outriggers and Crossarms

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Blog entry by English posted 07-31-2017 08:38 PM 1571 reads 0 times favorited 0 comments Add to Favorites Watch
« Part 3: Kayak Build: Painting the bottoms Part 4 of Building Kayaks for the Grandkids series Part 5: Making the Mast, Rudder and Leeboard »

At this point I needed to get the outriggers made so that they would be ready for paint at the same time as the Kayaks. To get started I knew I needed a outrigger that would support the weight of my grandson. He is 6’3 and 250lbs.

I looked at a lot of options for outriggers, Stitch and glue, made out of foam, inflatable, a frame covered with cloth and epoxied. He is quite tough on things so I decided wood with Fiberglass would hold up best. I found a plan on the internet for a small single sheet stitch and glue canoe. I took the plan and sized it down to 1/4 sheet. And lofted it onto a 1/4 sheet of 3mm lauan plywood. With the outrigger this size it will displace 90lbs of water. I plan to install them 36” from the center line of the kayak. This will make the buoyancy of the outriggers at 270lbs, per side.

The shape was cut out using a utility knife.

Two of these cut outs were then stitched together. The stitching is plastic wiring ties, pushed trough 1/8” holes drilled 1/2” from the edge and 4” apart.

The stitched plywood panel are then opened up in the middle and the tabs folded in and stitched with plastic wire ties.

I put blue tape on the outside joints any where that there was an opening.

I mixed up some epoxy and wood flour to make a batch of thickened epoxy, and spread a thick layer over the stitched seams on the inside of the outriggers. and epoxied on plwyood backer blocks on the flat seams at the end of the tabs.

After the epoxy cured I turned the outriggers over, cut off the plastic ties and sanded the outside joints smooth.

I mixed up more thickened epoxy and filled all of the holes and seams on the outside of the outriggers, also filled any low spots.

When the epoxy cured I sanded it smooth.

I coated the inside of each outrigger with two coats of epoxy to seal all the wood. I cut a frame for the top edge out of Douglas fir 2×4 stock. These were cut to compound angles matching the shape of the outriggers and were 1/2” thick x 1 1/2” tall. I cut a 2×4 down to 2×2 and made a cross brace on both end of the outrigger. This is to support the 7/8” Stainless steel pipe I will use to mount the outrigger to the cross-arm.

A top was cut out for each outrigger from 3 mm Okoume plywood and a 4” access port hole was made.

The tops were installed with epoxy and screwed with #6×1/2” stainless steel screws. Thickened epoxy was used to fill the screw holes and seam around the top.

The outriggers were then covered with 6 oz. fiberglass and laminated with epoxy.

After the epoxy cured the outriggers were sanded to remove the epoxy that was standing proud of the fabric. This step reduces the amount of epoxy needed to fill the weave.

Two epoxy fill coats were added to fill the weave of the fiberglass cloth.

The epoxy fill coats are sanded to make the outriggers ready for paint.

To make the outrigger cross arms I epoxied two layers of 3/8” marine grade Meranti plywood together with a layer of 6 oz fiberglass in the middle. I did this by cutting out 8 – 3 1/2” x 48” pieces of the Meranti plywood. Then epoxying them is a single stack by using a layer of plastic wrap, then plywood, then fiberglass, then plywood, then plastic and so on until all was stacked up and clamped in one assembly. The plastic will keep the plywood from sticking to each other. Sorry no picture of this step.

After the epoxy cured I sanded each cross arm, rounded over all the edges on the cross arms with a 3/8” round over bit in a router, and drilled a 35 mm hole in each end of each cross arm 36” apart. Next the 35 mm holes were filled with epoxy. After the epoxy cures a 7/8” hole will be drilled on each end through the epoxy at 36” on center to center/

The four cross arms were then coated with 5 coats of spar urethane.

After the holes were drilled the cross arms were cut to size. I used the scrap from the ends of the cross arms to make 3” wood washers with a 7/8” hole drilled in each one with a forstner bit. The washers were rounded over the same as the cross arms, sanded and finished with 5 coats of spar urethane. These washers will be used on top and bottom of the cross arms to supply a flat surface for the cross arms to move on and to help keep the cross arms from sagging.

Thanks for looking !!!

-- John, Suffolk Virgina



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