Kingfisher Drift Boat Building - Gluing the Scarf Joints

Now that I've got the scarfs shaped on the 3/8" x 4' x 8' Okoume Plywood for the sides I've got to glue them together with epoxy. First I'll have to gather up everything I need. Epoxy will be going off and I don't want to be looking around for stuff as it does. I've enlisted the help of my fishing buddy Mike Williams to help flip and place the sheets so I don't damage the feather ends of the scarfs.

I've got my epoxy stuff laid out and ready to get started.

What will I need, Let's see:

• The sheets laid up out and ready to go. Check!
• My epoxy and hardener. Raka Resin #127 - (Part A)- Low Viscosity and #350 Non-Blush Hardener (Part B) - Check!
• Epoxy pump type dispensers (2) - Check!
• Wood flour to make Epoxy Peanut Butter - Check!
• Tongue Depressor type of sticks
• Disposable Bristle Brushes
• Plastic plates for the epoxy. Check!
• An epoxy pallet. A scarp piece of plywood to mix and carry the epoxy around. Check!
• 2 - straight flat pieces of 1x8 at least 4 foot long to clamp the joints together. (For two scarf joints). Check!
• 3 mil plastic cut into 12" wide strips for under the scarfs and boards for clamping. Check.
• Hammer and 1" finish nails. Check!
• Clamps
• 8 plastic buckets and enough sand to fill them.!

Got everything and it's laid out ready to go.

Time to get'er done! More prep work.

• I'm going to glue the scarfs together on my table. It's stout and flat. I'm scarfing two 4x8 sheets together and adding one more 2' long sheet at one end to make a sheet that is 3/8" thick x 4' wide by about 18' long. This means I'm gluing two scarfs together so I'll have to work efficiently.
• I've decided to do each scarf separately, so I'll join the 2 - 4x8 sheets first and then do the 4' wide x 2 foot long piece after the first is clamped and weighted down.
• The 3 mil plastic needs to be stapled down so it doesn't get sucked into the glued scarf joint. I almost forgot this.
• I've got one sheet on the table with the scarf facing up. (Bevel up)
• I've got the second sheet lying flat on another portion of the table. It's much easier getting a consistent spread of the Peanut Butter Epoxy when it is laying flat.the table ready to lay down on top of the one laying on the table.

Time to get started with Mixing the Epoxy.

• I'll start by mixing 3oz. of clear epoxy and apply it with a brush to the faces of the scarfs. It will soak in so I'll have to apply some more after a few minutes.
• The Raka Epoxy I'm using has a formula of 2 parts of resin to 1 part hardener. This is where the pumps really are nice. Once the pumps are primed you just use the ratio of 2 pumps (shots) of resin to 1 pump (shot) of hardener. Doing a total of the three pumps mixes just under 3 oz.
• I've brushed the clear epoxy on the two mating faces and then re-coated them one more time.
• Once this is done I'll mix another 3 oz. of epoxy and add wood flour until the consistency is like "Creamy Peanut Butter". Smooth. Mix the resin and hardener before you add the wood flour. The epoxy should just barely sag and drop off the mixing stick when you hold it up. Add the wood flour slowly and mix thoroughly. It will become obvious when you get close to enough.
• Apply the Peanut Butter Epoxy using the mixing stick as a spreader to the scarf on the table. It should be applied as evenly as possible. Once the peanut butter is applied to the scarf I am using an 1/8" notched spreader to make sure the epoxy is spread evenly. The entire scarf must be covered. It doesn't have to be super thick on the scarfs, just a light coating that will be compress and squeeze out when the joint is together.
• Next I'll apply the same peanut butter on the joining piece that is laying on the table. It will have to be flipped over to join the two pieces together at the scarf.
• Next I'll flip the panel that that joins to the 1st sheet and lay it on top of the panel on the table, carefully aligning the sides. Then I'll line up the scarf joint. It should lay down and match the two surfaces perfectly.
• Check the alignment on the sides and press down on the scarf to see how it looks.
• If and when the side panels are straight and the scarf is lined up as straight as possible, place a 1" finish nail about two inches in from the edge right through the middle of the scarf. Place another 1" finish nail on the far side of the scarf (the opposite side). This is to keep the scarfs in place.
• Now run a screw through each panel into the table so that the panels do not accidentally move.
• Now press the scarf together further and force out any excess goo. Wipe the excess off with a mixing stick. You must have squeeze out. If not take the joint apart and add more epoxy peanut butter.
• Once the scarf is pressed together and the excess goo is wiped off, fill in any voids with the excess goo with a mixing stick.
• Lay down another sheet of 3 mil plastic on top of the scarfs and put a straight 1x8 on top.
• Put as much weight as possible on top of the 2x8. Buckets of sand work great. I used 5 gallon buckets filled with nails.
• Apply clamps to each end.

Here's the first scarf done on the two 4x8 sheets.

• Once this is done I'll repeat the whole process for the 4' wide x 2' long piece.

Here's the scarf where I've added the 4' wide x 2' long piece on the end.

• Let the goo dry over night. Can't wait to check out the joints tomorrow!

Last but not least. Clean up everything and get ready for sanding the next day.

Next Up - Cutting the Side Panels