Kingfisher Drift Boat Build - Drain Plugs

Now that the LineX bed-liner is sprayed on the bottom it's time to install drain plugs and wood inserts where I need to attached various parts to the bottom. The bottom is constructed with Plascore, a honeycomb plastic material. Screws will not attach to it. So essentially I have a 3/4" thick plastic bottom with Kevlar and fiberglass on both sides. I need to epoxy and glass in some epoxy sealed Okoume plywood discs to enable me to attach stuff.

I used 3 different sizes of hole saws mounted in a drill press to make the discs.

2 1/2" Diameter Discs. 

The first discs where 2 1/2" in diameter. These would be used for attaching pulleys for the anchor system. I will be inserting one in the transom and two under the front of the rower's seat. The ones under the rowers seat are placed butting up to one another.

Here are the two side by side holes under the rower's seat where a pulley will be attached. I used a 2 1/2" hole saw to cut through the top layer of Kevlar and fiberglass.

2' Diameter Discs

The 2nd set of discs were 2" diameter. These would be used to secure the foot brace brackets in front of the rower's seat. There will be 4 of them.

Here is a photo of a 2 inch diameter hole that has been drilled and then the plastic honeycomb removed 

The holes are bored with a 2' diameter hole saw just through the top layer and then the honeycomb core is removed by twisted the core out with a pair of needle nose pliers.

2' Diameter holes for the Drain Plugs

The drain plugs require 2 holes to be bored. I started off by drilling a 2" diameter hole through a piece of 1/2" thick Okoume plywood with a 2" hole saw. The holesaw has a 1/4" diameter pilot bit. Once drilled, I changed to a 1" diameter hole saw. I held the 2" disc in a clamp and used the 1/4" pilot hole to drill a 1" diameter hole inn the center.

The photo above shows the 2" diameter discs on the top row and the plug for the drain plug on the bottom. The brass drain plug is inserted into one of the discs.

Sealing and Installing the Discs

The discs were sealed with epoxy on all sides prior to installing them. They were then sanded with 120 grit prior to installing them. Once sanded I mixed up some epoxy peanut butter and epoxied the discs into their appropriate holes. The epoxy peanut butter was squeezed out of the holes as they were leveled. The epoxy was leveled and cleaned up and left to harden overnight. The next day I cut squares of fiberglass cloth and placed them over the plugs and flow coated them.

This photo shows the 4 - 2" diameter discs epoxied in place

Installing the Drain Plugs

Once the wooden discs had set up I had to drill through the LineX bottom. I used a 1" diameter steel bit. The bit scored the holes a bit so I recoated them with epoxy Once the epoxy had hardened the plugs were ready to be installed. The brass drain plugs were installed with 3M 5200 adhesive. The bottom flange and the outside surfaces of the drain plug were coated liberally. Once the plugs were inserted I used #8 x 5/8" brass screws to attach the brass drain plug to the wooden disc. I put 5200 adhesive in the screw holes.

This is a photo of the drain plug disc in the transom prior to drilling through the bottom. Note that the disc is about 3/16" below the surface of the bottom. This will flush out the drain plug flange.