Skeg - Cloth or just epoxy?

How thick of plywood? Over the years I made some paddles with 1/4 marine ply and used to take a round, (rat tail) file and carve an indentation in the plywood edge and used poly thin rope soaked in epoxy in the edges. Than a few further coats of epoxy. I did the same on some strip blades too.

You would be fine with a few coats of epoxy on the edges. if you mask the flat faces a bit proud with tape, you can fill the edges with a slightly thickened epoxy. Then sand it smooth. It will give you a bit more abrasion protection than just a thin coat of epoxy. You may have to do each face separately, since gravity is against you.

One thing to consider:

If you make the skeg a 'tight' fit in the skeg box, you can't afford to have the blade swell with water absorption.

So, for a wood blade, make the fit sloppy (like most commercial kayaks).

If you want to make a tight-fitting blade (like the Reg Lake skegs in the Sterling Kayaks), a plastic material like StarBoard is a better choice.

I made a few and this method worked well. I take some plexi (the inexpensive window replacement stuff) and rough cut out two pieces larger than the skeg. Sand both faces then sandwich them together with epoxy and a layer of glass in between. Then glass the outsides. You can tint the epoxy black so it looks official. Extremely strong substrate, inexpensive and easy to do.

The idea of a tight fit skeg boxes is the gap between the skeg and the box is small enough that material can not get between them to jam them up. You need to consider where you paddle to determine if this makes sense. If you only paddle in places with pea-stone beaches, it may work fine. However, if you land on sandy beaches, there is no gap small enough that a small amount of fine sand can not work its way into the gap.

This is especially true if you give your skeg any kind of foil shape. The shaped skeg will work as a wedge to more securely lock any grit that should find its way between, causing a good solid jamming situation. The tighter the fit, the more solidly it will jam.

Fine sand gets suspended in the water and is quite efficiently transported all the way around the skeg. A tight fit will jam, it is just a matter of hitting the right beach.

Loose fitting skeg boxes are less efficient, creating more drag as water swirls around the box, but they are significantly less likely to jam as larger gravel is less likely to make its way up into the box. I have about a 3/16" [4mm] gap on either side of the skeg and offset my skeg box from the center line and I have never had a jam on any beach with any grit or gravel size.

My skeg design also uses a supported control cable that can positively force the skeg to be deployed without risk of kinking, so minor obstacles can be pushed out, but I don't remember ever having to use that ability.

Good points from Nick about stones/fine sand.

No matter where you paddle, you should definitely have a cord hanging from your skeg so that one of your paddling partners can pull the skeg free after you launch. It's helpful to put a mark on the deck above the spot where the cord hangs.

Freya Hoffmeister rigs a cord loop to the cockpit so she can un-jam the skeg/rudder on her boat when paddling solo.