Repairing Skeg Box Leak, Documented with Pictures

I started on my repairs today. The hardest part, and the part that matters the most is the exploration and preparation. The exploration involves chipping, poking, prodding, and removing things that most sane people would cringe at. I consider myself relatively sane, and I was definitely cringing at some points. However, anyone who thinks they can just slap a patch over things without removing every bit of damage down to good material is just wasting their time.

I’ll update this thread as things progress. Note that I’ve done plenty of repairs and built many things in my life, but this will be my first time using fiberglass and gelcoat for anything serious. Any qualified input or suggestions will be both appreciated and considered with regard to my overall repair plan.

I have two goals with this project. The first and most important is to structurally repair the damage to my skeg box and restore it’s watertightness. The second, while the boat is dry and being worked on, is to repair a couple of serious chips and cracks to the gel coat. Some of these are cosmetic, while others could cause problems if left alone.

[Edit: You’ll see later in this thread that the cracks have become a larger part of the project. I’ve ended up stripping the gel coat from most of the coaming, building up the edge with epoxy and fiberglass, then re-applying gel coat.]

To start things off, I decided to get rid of the fiberglass hoop that I can only figure is there to protect the skeg cable from damage. Little good it’s done. Well, maybe. I’ve discovered that the damage to the skeg box area was more extensive than could be seen (no surprise there). It also looks like it’s been there for a long time without leaking fully. So maybe I knocked it on one of my recent trips, but the hoop still has to go, at least temporarily to give me room to work. A hacksaw blade did the job quickly. I also secured the skeg cable tube out of the way for future work.

After looking at it a bit more, I discovered the hoop wasn’t attached with more than one or two layers of glass, so proceeded to cut and chip the remaining uprights from the hoop from either side of the skeg box. This is where most of the cringing took place, with lots of ripping, cracking, and snapping noises. I did it carefully though, and most of the loosely attached stuff came off without damaging the box itself.

Then I turned the boat over and started chipping out the loose gelcoat. I was a bit surprised when I started doing this that there was an air gap behind the gel coat, not fiberglass! But, it must be done so I continued chipping, scraping and sanding until I found good material. Not at all easy to do “down hole”, using long instruments. I’m sure a proctologist has a more difficult time, but not by much. :wink: I went from seeing two small hairline cracks, to the following…

While I had the boat upside down I sanded and feathered a few of the large chips missing from the corner of the skeg box, preparing them for filling with gelcoat later.

Shining a light from below and looking inside the boat reveals the location of the damaged areas to be repaired.

And moving the light back inside, this is how I’m leaving things for today. The remains of the hoop have been sanded down smooth, and both the inside and outside are prepared for glassing and gel coat. I tried to remove the bolt that retains the skeg pivot, but it must have been installed before the skeg box was attached to the boat because it interferes with the hull before it can be fully pulled out, even at an angle. I could cut it out, but I’m not sure what I’d do to resecure it when done, so I’ll work around it as best I can.

A few questions for those of you who have undertaken similar (or more involved) fiberglass projects:

  1. How many layers of 4oz weave should I consider putting on the inside? How far beyond the damage, and in what shape? I have some chopped mat I could use as well, but my understanding is that it isn’t very strong.

  2. On the bottom, inside the skeg box, most of the existing glass under the gelcoat was little more than greyish-brown powder and was removed. Should I consider adding a small glass patch in these areas, or just rely on the inside reinforcement and gelcoat over this inside the skeg box?

  3. I was thinking of building up area where the skeg cable goes through. The idea being to create a flat area inside, or building up the top of the skeg box to accept a longer flat stainless steel reinforcing plate, sealed by a gasket between it and the hull. Am I overdoing it, or is there a better design you’ve seen that I can incorporate into the repair? Alternatively I could make a plastic piece that’s concave conforming to the top of the skeg box, and flat on top for the skeg fitting. There just has to be something better than the original design, which completely sucks.

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

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

@PaddleDog52 said:
I only say one thing to myself.
You also say it to us, unfortunately.

@Allan Olesen said:

@PaddleDog52 said:
I only say one thing to myself.
You also say it to us, unfortunately.

Why is it so terrible? Just my preference. Some like skegs. I have one kayak with a skeg. We all need skudders.

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.