Repairing Skeg Box Leak, Documented with Pictures

I’ve fitted and/or repaired about twenty skeg systems, and restored and repaired too many GRP kayaks.
I don’t consider the damage illustrated to be major. I would do the repairs using epoxy for strength and the ability to thicken the epoxy. I would first use epoxy resin thickened with Cab-o-sil or similar colloidal silica to peanut butter consistency to fill the voids, and then cover the top of the skeg box and the voids with three layers of 2 inch 4 ounce glass tape when the thickened epoxy has started to harden.
If you wish to repair the minor chips in the gel-coat surrounding the slot in the hull, bear in mind that gel-coat will not set in the presence of air. Either cover repairs with plastic film, or add wax to the gel-coat, or buy Topcoat (aka Flowcoat), which is gelcoat with wax already added: http://www.cfsnet.co.uk/acatalog/methods_flowcoating.html
Nick.

@Johnysmoke said:
I wonder if anyone sells a whole boxed assembly you could just drop in there?

If you mean cutting out the existing skeg box and glassing in a new one, I’m not sure that would be less work. Quite the contrary. I’ll likely get a similar opportunity in a few years though, as I have a cedar strip boat in the works as a long-term project. That will probably get a drop-in skeg assembly when the time comes.

@PaddleDog52 said:
I only say one thing to myself. Rudder. May be easier to use fiber glass tape for your repairs in there.

I’m definitely a skeg guy. I like the idea of a rudder, just never took to it. Mostly I don’t like the foot controls, but there are pros and cons to each system and I’m not about to start that debate in this thread.

@nickcrowhurst said:
I’ve fitted and/or repaired about twenty skeg systems, and restored and repaired too many GRP kayaks.
I don’t consider the damage illustrated to be major. I would do the repairs using epoxy for strength and the ability to thicken the epoxy. I would first use epoxy resin thickened with Cab-o-sil or similar colloidal silica to peanut butter consistency to fill the voids, and then cover the top of the skeg box and the voids with three layers of 2 inch 4 ounce glass tape when the thickened epoxy has started to harden.
If you wish to repair the minor chips in the gel-coat surrounding the slot in the hull, bear in mind that gel-coat will not set in the presence of air. Either cover repairs with plastic film, or add wax to the gel-coat, or buy Topcoat (aka Flowcoat), which is gelcoat with wax already added: http://www.cfsnet.co.uk/acatalog/methods_flowcoating.html
Nick.

It does sound like you have some experience doing fibreglass work. I don’t consider the damage major either, but it’s enough that it needs some careful attention to fix it properly. Major would be more like reattaching the bow after a car-topping accident. I doubt I’m ready to attempt that one yet… but I’d sure try if it happened. :slight_smile:

I wish I would have included some cabosil (fumed/coloidal silica) when I obtained my supplies initially, as I’m seeing reasons to have it now that I didn’t then. Checking out the automotive shops in the area I get blank stares when I ask for it by various names, and I’m pointed to the “Bondo” brand fiberglass repair kit. In lieu of this, I’m thinking to try making some very fine wood flour by grinding clean fresh cedar sawdust.

Good advice on the gelcoat, however I did do some research ahead of time and got myself the waxed stuff. This means that if I have to build it up I’ll have to grind/sand it between layers, but I think it will be easier for me to work with this time.

West Marine has many thickeners depending on your use. Fairing compounds or structural materials. I find West Systems very easy to use. Pumps make it easy to make an additional squirt fast if running low so you really get near zero waste. I used the West epoxy and fiber glass tape in doors of trucks and it easy to handle. One tip I can give you is make sure you can reach in and get materials into position and see with a few dry runs if brushes or tools reach an area to place glass.

West Marine would be a great store to get the stuff at… if I had one near me, which I don’t.

I obtained most of the supplies from an online source within my province, but it would be nice to fine a marina or something nearby to pick up odd stuff I don’t have to wait almost a week to receive.

Good idea to do a trial run. I’m excited to get going on the glassing, but there’s just a little more prep to do before I start that. I’m going to do a little practice off the boat first to make sure that my mixing is appropriate and to see how well the glass wets out. I plan to mix by weight because $30 CAD for the dispensing pump set seemed a bit high. I’ll probably go that route when I have a much larger project though.

Picking an epoxy system when you’ve never used one before isn’t easy. There are many reputable brands and one person swears by this and another swears by that. I ended up going with MAS Low Viscosity FLAG Resin and MAS Medium Hardener. This system doesn’t leave you with amine blush to clean up between layers. Maybe it’s not as bad as it sounds, but seemed like something best avoided for a newbie. The medium hardener might take longer than I’d like, but again, I’m more interested in getting things done right than I am doing it fast.

Along with fixing the skeg box, I’m also taking this opportunity to reinforce the coaming, which had multiple severe cracks in the gelcoat, and one side has a larger vertical crack down the inside of the cockpit/coaming.

In chasing down the structural cracks in the glass itself under the gelcoat, I’ve decided to remove almost all of the gelcoat from the coaming. The only places I’ve left are the front and back, which appear strong and stiff without cracks. The rest of it is going to receive a number of reinforcing layers before covering it back up again.

I don’t know what they were thinking, but there was at least 1/8" of gelcoat overtop of only about 1/16" of overhanging fiberglass. Is this normal? I’m thinking more glass, less gelcoat would make much more sense.

It was a very messy process. I gave the boat a good wash down after to remove all the plastic dust before it became embedded in every crevice.

No pictures of this right now but I’ll try to take some before I begin the next step.

What kind of fitting is on the end of the cable housing? If it’s not threaded, I would suggest that you get a threaded fitting for it. That way, you can embed a threaded plate (preferably) or a nut (better than nothing) in your repair, that the housing fitting can mate to. That should result in a watertight connection and improve the serviceability of the system in the future.

There are a couple of hand tools that I find indispensable for fiberglass shaping, a rasp (the finer sides of a typical 4-way rasp work well) and a 2" carbide scraper. They’re available at pretty much any hardware store or home center.

The original fitting was a plastic compression fitting, the OD being 1/4". The threaded end went through the top of the skeg box and was held by a nut inside the skeg box. The nut on the outside was mild steel, oddly enough, and was fairly rusted. It was tight enough inside the skeg box that the only tool I could find to get a grip on the nut was a pair of needle nose pliers on two flats. Needless to say, this isn’t a great way to grab a nut, and didn’t work anyway. I ended up partially drilling out the fitting from the outside to finally remove the nut.

I have a brass compression fitting that I’m planning to use as the replacement. My intention is to make up a small block that’s going to be glassed to the top of the skeg box (inside) that will be threaded to accept the fitting. I’ve carefully drilled through the fitting so that the 1/4" OD skeg cable will pass through the fitting, though the boat, and protrude slightly into the skeg box. I’ll be applying sealant between the protruding tube and the gelcoat. This will give a few layers of protection from leakage, and protect from water seeping into the glass fibers around the repair. At least, that’s my theory. :slight_smile:

One thing I’ve learned so far is to get the catalysed resin OUT of the cup as quick as you can! I didn’t realize that my ~3 hour gel time was for thin set, as opposed to pot life, which at the temperature I was working was less than 15 minutes! Fortunately I found this out while first testing things out and only baked about an ounce into a plastic cup.

I’ve been taking fewer pictures than I originally intended. I’m not about to grab my phone from my pocket while my gloved hands are tarred and feathered with glass and resin.

Cool the resin and use lass hardener get a photo buddy

Here are a few pictures showing what I’ve been up to the past couple of nights. My lighting is horrible, which is why every picture seems to be a different brightness and colour.

Near thigh brace, dry edges of glass exposed and gel coat chipped on edge.

I started out being more conservative, cleaning back only 1/2" from the cracks with the intention to put strips of glass over them and then re-apply gelcoat.

All of these edges were cleaned up until I no longer found loose, dry weave. It went farther than I figured.

On the right (starboard?) side, right in front of the seat, I had a very serious crack. For a maximum strength repair, I prepared the area for glassing by grinding a deep, wide Vee.

The cracks were hard to get a picture of, but in this one you can see some lighter lines running the length of the coaming. These were through about half of the existing fiberglass layers so I prepared them by grinding out a groove.

Poor boat… Most of the gelcoat removed from the coaming. If you’re considering doing anything like this, make sure to remove the seat BEFORE you begin. This is incredibly messy and I’m probably going to be finding green powder on everything for years to come.

After applying three layers of glass on the inside of the skeg box, I can see that it has wet through on the underside. It shows just how porous the fibreglass was in this area!


I filled the grooves that used to be cracks with resin filled with chopped strands. I’d have preferred silica but wanted to get on with the project. This isn’t really structural, as it’s too narrow to get a good bond with the surrounding material It needs to be filled so that the subsequent layers of glass lay flat on top of it with no voids. I covered with cling film to shape and minimize sanding later,

Looking at the skeg box after adding three layers of glass, it doesn’t look much different. I suppose that’s a good thing. I used cling film on this one too so that I could make sure I had things well-smoothed and saturated without being able to see in there very well.

After some rough shaping/sanding, I applied the first layers of weave to the coaming. Some of the remaining voids were filled using epoxy thickened with the coarse sanding dust from shaping. It worked very well.

The large crack is getting special attention. Apart from the larger piece of glass, it’s also getting smaller pieces built up in layers. This will eventually make it flush with the rest of the coaming and should be very strong.

With the boat upside down, I heated the skeg box with a lamp inside. Then I applied resin to the dry areas to wet out any remaining porous areas. The heat helps reduce the viscosity and it flowed very well into every nook and cranny. I used a long, small paint brush for this work. After it was well saturated, I added some tiny pre-cut fiberglass circles and pieces roughly matching the shape of the hole. Since it turns almost transparent when wetted out, there’s not much to see here. I plan to re-drill the hole when I’m done with the glass and gelcoat.

And that’s it for now. Hopefully some of you are finding this interesting. I know I am.

Just before applying repairs, are you treating the repair areas with acetone? Waxed paper taped over repairs is sufficient for curing.

@magooch said:
Just before applying repairs, are you treating the repair areas with acetone? Waxed paper taped over repairs is sufficient for curing.

Between layers I’ve been vacuuming as much dust as I can suck out from the weave and surrounding area, plus a wipe down with acetone.

I’m thoroughly confused about the gel coat thing. I just finished preparing the coaming for the first coat of gelcoat. When I picked up the can for one final reading of the instructions I noticed, in bold print, “NOT FOR USE OVER EPOXY” (or something to a similar effect). Why I didn’t notice this the first time I read the side of the can eludes me.

So, to the Internet I went. There are quite a few YouTube videos where gel coat is applied over epoxy, and it doesn’t seem to be anything other than the “standard” polyester gelcoat. I’ve been watching this guy’s videos, and though this test is less than scientific, the results are convincing.

https://www.youtube.com/watch?v=GwS4YgoGFm8

So at this point I’m thinking I’ll be fine with very good surface prep. But to be on the safe side, I’m going to try applying a small amount to a test piece I made at the beginning and do my own adhesion and flexion tests.

When it comes to flex, I shouldn’t have much of an issue anymore. I lost track of the number of layers I added to the coaming to stiffen up the lip. I probably doubled the thickness to the sides. What I fail to understand is why it was built like this in the first place. Initially the coaming lip had roughly uniform thickness all the way around. On the front and back (the places I’ve left the gel coat on) there was close to 1/8" of fiberglass and about 1/32" to 1/16" gelcoat on top of that. This gives enough stiffness I can’t noticeably flex it with my hands. On the sides though, it was pretty much reversed! This is why it cracked in the first place. I now have about the same thickness all the way around the coaming and it’s nice and rigid. Here’s hoping there wasn’t supposed to be more flex built into it for some reason… but that doesn’t explain gooping on the gel coat at 2-3 times the thickness of the underlying composite.

Like many repair projects, this one got a lot bigger than I anticipated. Not to worry though, things are going well; just taking longer than I had hoped. I’ve been spending more time on the coaming because it needed the attention if I wanted to perserve the boat and prevent further damage. I’m still working away at the skeg box too, but while doing the fiberglassing of the coaming I avoided flipping the boat over to work on the bottom.

Here are some pictures since my last update, with descriptions to suit:

This is the block I’m making that will be glassed to the top of the skeg box. I drilled an oversize hole through the block then cast the fitting and a piece of 1/4" steel rod in the centre of the hole with epoxy resin. I was dreading taking them apart, but the wax I put onto the parts made it come apart easily. I had to do some post-casting filling near the top of the fitting due to the epoxy absorbing into the wood. “Next time” I do this I’ll coat the block first and then do the casting.

I picked up a package of 2oz disposable polypropylene cups at the local Dollar Store. These work great for small amounts of epoxy and gel coat. I’ve been mixing everything by weight to the nearest 0.1g and everything has been curing up nicely. Most of my epoxy batches were 10g of resin and 5g of catalyst. This was enough to wet out everything for one side of the coaming. Stated another way, the cup was about 1/4 full, so about 1/2 fl. oz.

I’ve been alternating between smaller sections that needed built up and large pieces that span the coaming length. Clothes pins hold the strips nicely for marking cutouts and can help position it when setting the long strip into wet epoxy. For each strip, I’ve wet it out with the edges hanging over, then trimmed after the epoxy has cured.

Close up showing the thickness of fiberglass vs. gel coat at the rear of the coaming. Notice how the fiberglass thickness tapers off to the left of where I’ve feathered out the gel coat. This is not the result of me grinding down the fiberglass, rather the thickness transitioned on both sides at this point.

Finished fiberglass work just behind the thigh brace. The old has been feathered into the new to help lay a smooth gel coat layer on top of everything.

The large vertical crack repair can no longer be seen. It has been properly built up with layers to bring it flush with the rest of the surface.

This is a neat trick I picked up from YouTube. After mixing pigment into the gel coat, put some un-catalyzed product onto the surface that’s being matched. I found I could get very close, but I’m not worried about it being exact because I plan for the final layer to cover the existing gel coat.

Beginning to build up the gel coat in the lowest places. You can see I’ve also taken some time to mask off the boat much better than before. This will protect from errant gel coat, coarse shaping tools, and the slurry wet sanding is going to produce. [Hindsight: I should have done this right at the start!]

After two layers of build up, with sanding and acetone cleaning in between (due to gel coat wax). I’ve been rubbing vigorously with a very wet acetone soaked rag, then wiping off the surface with a separate rag - a clean part of the rag each time. [Hindsight: I’d use unwaxed gelcoat next time to more quickly build layers without the work in between. There are lots of ways to seal off the unwaxed gel coat to get it to cure completely. Perhaps the easiest being to add wax for the final layer.]

Applying the gel coat is like trying to paint on toothpaste and get a nice finish. Working with the epoxy was much more satisfying, but at least this stuff sands down quickly. I’m focusing on just putting it on heavy right now to build some thickness. Then I’ll shape and smooth for as long as my patience holds out.

And no, I’ve not forgotten about that skeg box. With a small brush taped to the end of a stick, I carefully dabbed on some gel coat on the patches inside the skeg box. This was painstaking work getting the brush into the slot without smearing the gel coat down the side, but I got it done. I used a sheet of plastic on the end of a larger brush, also attached to a stick, to smooth it out as best I could to minimize sanding… Which, you guessed it, has to be done on the end of a stick. I’ll be completely finishing the bottom repairs smooth then drilling a new hole that’s smaller than the original. After I get this done, I plan on using the hole to locate the block on the inside. Then I’ll glass it in place and the skeg box part of the repairs should be complete.

Gelcoat works fine over epoxy if it’s fully cured and the surface is clean before the gelcoat is applied. If you have any issues with the gelcoat not curing, clean it off, then use a gentle heat source to help cure the epoxy overnight. Clean the surface again and reapply the gelcoat. That typically works.

cool

It’s been almost two weeks since I last updated this because other life responsibilities have intervened. Not to mention the past long weekend, which saw me paddling around Philip Edward Island near Killarney, Ontario in my other boat, a CD Sirocco. It’s actually a very good thing this has happened because I would have otherwise not had the opportunity to paddle the Sirocco in rougher conditions at “touring weight”, which is completely different than paddling it empty. It’s a very pleasurable experience!

But I’ve been back at it since then, and have about a 3 hour wait for epoxy to set up enough to continue working. It seemed an appropriate time to update things here.

Most of the work up until today was still on the coaming. I’ve determined that working with gel coat on anything but a female mold is just about the least fun one can have. I thought I’d get smart about it and use masking tape to create a dam and build up a very thick coat that could be sanded and shaped without thin spots. [Spoiler: Good idea, but didn’t completely work out]

This is what the work in progress looks like. Here I’m fairing the gel coat so there are no rough transitions between old and new.

I’ve continued to swap back and forth between the coaming and skeg box while waiting for one or the other to cure. I’ve added more gel coat to the chipped corners of the box, and added a very thick layer inside the box over the glass repairs. I used a strip of tape running down inside the box to mark the location of the existing hole so I know where to drill later. [Hindsight: Tape was a bit close to the gel coating area and edge got stuck underneath a little bit. No worries, this area is not visible when done and won’t cause water intrusion issues.]

I didn’t go nuts on the sanding here. I just smoothed out the high spots and feathered in the edges a bit. I then painstakingly marked the location of the hole to drill using a sharpie taped to a stick. You can see I managed to goop some gel coat on the sides of the skeg box too. This was not well-adhered and chipped off fairly easily.

How to glass in the block that’s going to hold the compression fitting has been the subject of much subconscious effort. If it wasn’t already obvious, I’ll restate that working inside the stern hatch is very difficult. I can barely get one arm inside far enough to reach to the back of the skeg box, and when I do I can get my head inside the hatch only far enough to see with one eye. Working with any kind of dexterity in there is not going to happen. Most of my work needed to be done by feel so I planned ahead and made up some pieces that should fit exactly in place and not require much screwing around to position. I cut three pieces with about 1/4" difference in the length of the tabs. This one was the first and looked more ragged than the rest. I also added a hole in the middle of each to clear the fitting.

Last night I spend some more time sanding the coaming. There are a few places where I’ve sanded through to the original gel coat, but they aren’t very noticeable if you aren’t looking for them (like I am). The progression of sandpaper grits I used to do this was: 60 - rough shaping, 120 - smoothing and feathering, 220 - remove deep scratches from previous, 400 wet - remove 220 scratches and begin to be shiny, Heavy duty rubbing compound - reduce wet sanding scratches and polish to an acceptable shine. I definitely took shortcuts in jumping sandpaper grades because I keep reminding myself that perfection is not the goal here. A perfectly smooth mirror finish would actually look rather odd on a boat where nothing else looks so nice! The goal was to fix the problem that had caused the original cracks, which I did, and then to make the appearance at least as good as before. I believe I’ve accomplished this. There’s also no reason I can’t do more later if I decide I want to restore more of the boat to original appearance. Though I’m unlikely to do this, as I’m much more interested in paddling it than just looking at how shiny it is.

Back to the back, I return to the stern. I thought it might be a good idea to test fit the skeg and make sure the cable passed cleanly though the new hole I drilled. My earlier efforts paid off and the hole seems to be in exactly the right place. I did have to trim a little off the skeg itself to clear the thickness of gel coat near the pivot point. I suspect this may have been the cause of the damage there. Not a problem anymore.

Getting the block lined up with the hole and on top of the skeg box was another thing I had well planned. After dry fitting and determining the angle the hole would sit at, I attached a well-waxed rod through the hole and centered in the skeg box. Tape was enough to keep this in place. It doesn’t need to be exact, but if it’s really wonky the skeg cable will bind.

Here’s the result of lots of planning and staging things to grab while the clock was ticking. I used some white pigment in the epoxy to help see where I was putting it, and to increase the aesthetics of the wood block I’m adding. The wood itself is well encased in epoxy, so it is now essentially a plastic block with a wood core. The procedure was:

  1. Do wet layup of 3-layers of cloth previously cut for the purpose. This was done on the bench on parchment paper.
  2. Spread epoxy on skeg box, or rather just goop it around as best I could by feel and intuition…
  3. Add thickener to remaining resin and “butter” the bottom of the block and the top of the skeg box
  4. Slide block onto rod and press firmly on top of skeg box
  5. Add more thickened epoxy to fill any gaps
  6. Remove pre-wetted cloth from parchment paper and place over block, fitting, and rod. Smooth down edges with gloved fingers
  7. Apply cling-film and smooth some more with bare hand.

The moment of truth will come later today when I remove the cling film, sand down the rough spots, and examine my work. I plan to add more thickened epoxy to fill and smooth the surface if needed, or possibly a few more strips of glass if things looks really bad.

One more thing I should add, as I’ve discovered a small error in my assumptions regarding the mixing of epoxy by weight.

There is a small difference in the density of resin vs. hardener, which means that mixing by weight is not the same as by volume. In practice though, the difference is small and many online sources will say that things work out fine in the end.

For the epoxy I’m using, MAS LV and medium hardener, the ratio for mixing by weight is 100:45, as opposed to by volume which is 2:1. Ratios for different brands and products vary slightly, but all I found are fairly close to this. I don’t anticipate problems with a little excess hardener, but I’ll be using the correct ratio for future batches.

Makes my head spin, Sparky, but sure looks like you’re doing a great job.