Part 5: Fin Box and Leash Plug Install

Fin Box Installation

Some fin systems, such as FCS X2, single-fin boxes, and Greenlight’s favorite ProBox, are installed after your hot-coat has cured. There are also a few quality fin systems, such as FCS Fusion, and Futures, which are installed directly into the foam prior to the lamination step. We are not going to go into specifics of the installation for each of these systems. We recommend that you go to the websites of each of these fin-system providers where you can view installation videos and download complete installation instructions.

 Regardless of which system you use, you will need some specific jigs and tools for the installation. Greenlight sells the installation kits for ProBox fin systems here, as well as a complete fin box/leash plug install tool kit here.

 Another thing you need to consider when installing fin boxes into EPS foam is to use either a slow-curing hardener or Kwick Kick resin. The heat from fast-curing epoxy has been known to melt EPS foam in fin-box installs. Better to play it safe with slow-cure, or Kwick Kick, both of which don’t exotherm as much when curing.

 Leash Plug Installation

Installing leash plugs is a fairly simple affair, but you can screw it up if you are not careful. Most leash plugs are installed after the hot-coat has cured. For EPS cores, Greenlight has invented a Gore-Tex Vented Leash Plug, which helps to equalize pressure inside/outside the surfboard core due to hot temperatures or pressure changes (airplane holds). If you are making an EPS/Epoxy Board, we highly recommend you install a vented leash plug. It costs a few bucks more than a regular leash plug, but you get some peace of mind that you won’t have overheating/delaminating issues caused by big swings in temperature or pressure.

 The Gore-Tex Vented Leash Plugs need to be installed with a fairly specific (but still simple) process, so if you go this route, follow the instructions that come with each plug. For any leash-plug installation, there are a few tools you need to do the job right:

1.       Power drill

2.       Forstner Bit or Holesaw Bit

*Vented leash plugs and FCS leash plugs require a 1" or 1 1/8" diameter bit, Bioplastic leash plugs require 1 1/4" diameter bit.

You can make a drill jig by using your bit to drill through a thin scrap piece of masonite or plywood. Then tape the jig to the board to ensure the bit does not run across the hotcoat before penetrating the lamination and foam.

 Drilling the Hole

Put tape around the bit as a visual depth guide so that the bit cuts about 1/16” shallower than your leash plug depth. This will give you something to sand off into a flush, leak-free edge. Tape the drill jig to the board with masking tape at the desired location. You can pulse the trigger of the drill to slowly bore through the fiberglass, making sure to keep it at a 90 degree angle so you don’t distort the hole. Keep a light touch on the drill, because once you get through the fiberglass, the bit is going to cut much faster in the soft foam. Drill with light pressure until the tape depth guide gets near the drill jig. Check the depth with the plug and drill a bit more if needed. Blow any excess junk out of the drilled hole, and now you should have a nice clean hole for the plug install.

 Installing the Plug

The first thing you should do before mixing your resin for the leash plug is to tape off a little area around the hole on the deck of the board using high-temp masking tape. This masks the board from drips and overflow, so you don’t have to sand them off later. Also, put a strip of high-temp masking tape over the top surface of the leash plug itself. Trim the tape around the circumference of the top of the leash plug, and make sure you have a good seal between the tape and plug to prevent resin from dripping down into the plug.

 You only need about an ounce of mixed epoxy for a leash plug install, so we recommend mixing it in very small graduated mixing cups that have small enough increments to make sure you can accurately gauge your 2:1 resin/hardener ratio. After you’ve added the hardener to the resin, a nice touch (but not totally necessary) is to add some opaque pigment to the mix, along with a teaspoon of thickening agent which helps reduce air bubbles. Additive F is not needed for your leash-plug install.

 Make sure everything is mixed in thoroughly, then pour the mixed blend into the hole you drilled in the board. Pour enough resin in to fill about 1/3^rd of the depth of the hole. Then take your leash plug and carefully press it into the hole. The resin should rise up around the sides of the hole. You want the resin to rise just above the surface of the board, so pour some extra resin in around the sides of the plug until it reaches that level. There may be some settling of the resin, so double check after a few minutes and top off the fill to make sure the resin cures slightly above the surface. You will sand everything flush and remove the tape once you do your final sanding of the glass job.