How to Make a Fiberglass Skeg

A skeg is an effective tool that can help control a kayak in difficult conditions. In quartering wind and waves, it can be a godsend. For the average backyard builder, commercial skegs tend to be expensive and most backyard builders will have the skills to fabricate their own. When looking at skeg options, I’ve never been able to find a wooden one that satisfied my sense of durability and simplicity. So, I set out to make a fiberglass skeg that would work well in a wooden kayak. Below you’ll find the steps that I took.

1. Come up with the size and shape of the skeg that you want to build. I picked a low profile design that would take up limited space in the cargo hatch. It’s simply two circles connected with edges and then one edge shaved off.
2. Next build a plug. A plug for the skeg box is a male mold that you’ll lay the glass around to build a skeg box. Depending on how you plan on controlling your skeg, you may have build a box to accommodated bungees, lines, wires, etc… With a standard through the top deck bungee deployment/static line retracting/jam cleat system similar to those you’ll find on a NDK or Valley kayak, you’ll need a plug that is 3/4″ wide, so you can use standard 1″s to construct your plug. For a wire skeg system, you could use two pieces of 1/4″ plywood glued together for a thin skeg box. The shape you make your skeg box, needs to be large enough to hold the blade plus any ropes, bungees, etc… For my skeg box, I drew a box large enough to accommodate my skeg blade shape, plus ropes, and then subtracted the width of the hull from the bottom. I also added a 3/4″ wooden dowel to the top to allow the bungee and static line to run up from the skeg to the top deck. The bungee will be attached to a deck fitting and the static line attached to a jam cleat behind the cockpit of the kayak. Make sure to finish and sand your mold, because the surface of your mold determines the quality of finish on your final part.



3. Find two pieces of glass that are large enough to hold your skeg blade. Clean these.
4. Buy a quality paste wax and some PVA Mold Release. I used Evercoat Mold Release and Star Bright Paste Wax. Coat the glass pieces on one side with four coats of paste wax and several coats of PVA. You can spray the PVA, but for a job this small it’s just as easy to brush it on. Also, coat your wooden mold with three or four coast of paste wax and several coats of mold release. The mold release I used is purple, so I could see that the mold was coated enough for my job.



5. Next layup the skeg blade on one piece of glass that you coated with PVA. I used epoxy fiberglass mat, which is a mat that is designed to be used with epoxy and not one of the esters. I laid up my blade to come to a thickness of 1/4″ after compression. Mat tends to fill with air, so use a fiberglass roller to force out the air bubbles after you have all the pieces wet out. You should also squeeze out excess epoxy. After you’re satisfied with bubble and excess epoxy removal, place the second piece of glass ontop of the fiberglass and add weight to the top of it.



6. You can layup the glass onto your skeg box mold now also. Use a combination of fabric fiberglass and mat. I laid a 6 ounce piece onto the mold first, then two layers of mat and then two layers of 6 ounce. You can set your mold onto a surface covered with saran wrap to guarantee that it will not stick to the surface. If you want a tight layup, cover your fiberglassed mold with peel ply and then wrap it with electrical tape to compress the fiberglass to the mold.



7. Wait for the glass to setup.
8. Now the scary part, cut a hole the size of the box into your hull. After it’s cut, lay a piece of glass around the opening and maybe use some thickened epoxy to help reinforce the opening.



9. Drill a hole in the skeg box so you can insert the bolt to serve as the pivot point for the skeg. Insert the bolt and enough rubber washers in the skeg box slot to make sure you get the wiggle out of the skeg blade. The 1/4″ bungee will help stablize the skeg when combined with rubber washers. I glassed mine into place after covering it with thickened epoxy. I used peel ply to make the final surface nice and smooth.



10. After the glass is set up, glass in the skeg box by fiberglassing it into the hull. Make sure that it is glassed in vertically or your skeg will protrude from the bottom at an angle.



11. Now, for a through the deck bungee system, cut a 3/4″ hole in the deck and PVA and paste wax a 3/4″ dowel. Run this down the hole to the hole in the skeg box. You can now wrap this all with glass, peel ply, electrical tape, or you can just glass a 11/2″ section near the deck and use plastic hose and hose clamps to connect them. For other systems, you’ll have to dream up other connections to make this work.



12. Next, set up the skeg for the line and bungee cord. Drill two holes into the skeg. The first is along the bottom further forward of the pivot point on the skeg. The second is on top of the skeg to line up with the 3/4″ dowel. Insert the skeg into the box using a slot you cut into the skeg at a little over 90 degrees to the bottom line of the skeg.
13. Attach the bungee and run it around the bolt and up through the hole in the deck and anchor it to a fitting on the deck. Then attach the jam cleat and static line.



14. Play with your skeg.

Finished Pictures of Homemade Skeg

Thoughts About Installing a Skeg While Building

The skeg I installed was a retrofit to a boat of mine. If I were installing a skeg to a boat under construction, I’d do it differently. The first step that I’d take is to cut the hole in the kayak and wrap the opening with glass and thickened epoxy. The second thing I’d do is insert my mold into the hole and glass right around it while the plug was installed. This way, I would attach the skeg box and lay-it-up at the same time. I think that laying peel ply over the skeg box and wrapping it in electrical tape would also be very helpful.

Thoughts About Installing a Wire Controlled Skeg

Construct the skeg box using a mold 1/2″ thick. On the top stern of the skeg box drill a hole to run your tubing into. Then glass your tubing into this hole. Run your tubing past your bulkheads to a control box near your left hand in the cockpit.

Figure out a way to attach your wire to your skeg using a screw that you can back out. I’d drill two holes that intersect and run the wire down the one directly below the tubing. The second I’d thread in a screw. Then unthread that screw and insert a bolt with the same thread pattern. After inserting the wire, the screw should be tightened until it locks the wire into place.

For the actual skeg, I’d lay it up slightly thicker than 1/4″.

Other Systems

A slick system dreamed up by Björn Thomasson uses two cords that run through tubing and emerge on the deck. One cord pulls the skeg up and the other drops the skeg. They are held in place with a piece of bungee. This is a slick system and highly repairable in the field. Read more here (Opens in a New Window): Björn’s Instructions.

Björn wrote the following on the Kayak Building Bulletin Board:

“The skeg on my Njord worked as planned, without any problems for the four years since built.
A control line as a loop from the skeg through two tubes emerging on the fore deck in front of the cockpit – the loop held tight with a short piece of bungy chord.
To replace the skeg or lines etc, untie the bungy chord, pull the skeg vertical and lift it out and untie the control line knots.
The fat NACA-shaped skeg has less resistance and is more efficient than a thin plate. On the skeg i attach thin foam washers to keep it centered in the box. This reduces noise and makes sure the friction in the system is where it must be – on the skeg and not the lines.
The only disadvantage is that, with my configuration and skeg size, there is a short line travel from up to down, just 4 cm, which makes precision handling a little awkward in winter with gloves. But in reality that is a minor problem – when needed you just tug the line and the luffing problem is reduced by at least 90%.”

Other Resources

I drew some information from Getting on Track by Jamie Brown in Sea Kayaker Magazine, June 1995. That article addresses wire skeg systems in more detail than I do.