Kayak repairs and maintenance

I have been asked a few times over the last few years about how to do repairs on composite kayaks, particularly about gelcoat repairs. I've been pretty busy recently doing just that kind of repair, so I thought I'd film the process to illustrate how I go about these kinds of things.

First some background - it's important to point out from the outset that I am not a professional, or even remotely expert, kayak repairman. But I do have a fair bit of occasional experience working with GRP (Glass Reinforced Plastic, as fibreglass construction is more technically called) since I was a kid in sea scouts, when all we had were GRP kayaks and they got regularly bashed and smashed on the rivers and we were perpetually repairing them ourselves.
It's also worth noting that I have a very practical approach to work like this. It could be described as "agricultural", and by that I mean it is functional and effective, but not necessarily showing much finesse or perfection. I definitely feel that the perfect is the enemy of the good. If I tried to make things perfect, I'd never get anything done.

So, the boat I am working on here is a Rockpool Taran 18.
A friend saw the below ad on Facebook and brought it to my attention. She knew I had a curiosity about Fast Sea Kayaks, and the Taran certainly qualifies as one of those.

I was at sea when the boat came up for sale, so I couldn't view it, but as it happens I had seen that very boat last summer when Ariel Gazarian was paddling it around Ireland and I met her at The Gobbins.
She had borrowed the boat from Steve Smith of Paddle North, and he was now putting it up for sale.

I had a fair idea that the boat would be pretty worn from all its travails, but I asked Steve to send me some video of how she looked now.

Based on those videos I decided to take a chance on it, knowing that some work would be required.

Luckily for me, Steve was able to take the boat to Achill, and Jon Hynes was able to take it from Achill to West Cork, where I was able to pick it up about a month later.

So with the boat finally in my possession, I was able to assess it properly.

Some things were immediately clear - 

• The deck lines, toggle and bungies would all have to be replaced.
• The original glass seat had been cut out, but a foam seat had been bought and would have to be fitted.
• There was significant gelcoat damage top and bottom.
• There were some proper dings that would have to be investigated further.
• The was a significant amount of foam padding, most of which would have to go (Ariel is not a big person).
• The front hatch cover had begun to tear, and could fail any time.

On the positive side -

• The boat was structurally sound.
• The rudder and foot pegs seemed in good condition

Just after I started removing the deck-lines, I realised I should take some photos so I'd know how they had to go back on!

This wear on the top gelcoat looks like it was caused by friction from a wheel or something like that. I decided to sand and polish this divot rather than try to fill it.
Later I found a proper chip elsewhere in the deck that will need to be filled with gelcoat.

With the deck-lines, bungies, toggle and backrest removed, I decided to tackle the hull gelcoat first. 
There were thousands of superficial scratches that I planned to ignore, but also plenty more significant ones that I would need to fill. By rights, the thing to do would be to gouge out those scratches with a fine rotary tool, such as a mini-die grinder or Dremel, but I was happy enough to clean them out and feather the edges with a scraper.
Feathering the edges is a common technique for repairing paint and composite materials; it means to remove any loose (not fully bonded) material, and to make sure that the transition from original coating to new coating is a gradual slope, not a hard cliff-edge.

In a way it may have been better using the scraper because the pressure applied by the scraper blade quickly revealed any areas where there was damage to the GRP structure underneath the coating. As it happens, I found 3 holes in the hull, one under the seat and two a short distance behind the bulkhead in  the aft hold. They were small holes, about big enough to push a Euro coin through, and luckily they were easy to access. It they were far forward or aft, I might have had to do the repairs on the outside, which would have been ugly (with my level of expertise/skill anyway).
The clips below are all of the hole in the cockpit, as that one was easy to film with my phone while working on it.

The first step was to sand the area of the repair. This is mostly to make sure the area is perfectly clean and dry. Any oils or moisture or other contaminants will badly affect the ability of the polyester resin to bond correctly with the substrate (in this case, the substrate is the boat). I am using rough sandpaper to clean the area. Coarse paper (P60 in this case) is better than fine paper, as a polished surface isn't great for wetting i.e. there is more surface area for the resin to adhere to, making a stronger bond.

As you can see, filming inside the aft hold with my phone was never going to work.

After sanding, all particles of dust and dirt must be removed.

I cut out small patches of glass mat. each hole would be covered with 3 layers of glass. The first layer only slightly bigger than the hole, the next layer slightly bigger than that, and the final layer slightly bigger again.

All ready to go. I never claimed to be the tidiest worker in the world!

Next step was to mix the resin with the catalyst. 
Of course there is a correct ratio to mix the catalyst, in this case it's supposed to be 1% - 3%,  but I judged it by eye. I almost certainly added too much, but the weather was cold and I wanted to make sure it would go off in a timely manner.
Add too much and the resin may go off before you've had time to apply it. If you add way too much it could actually overheat and cause damage, or maybe ignite a fire. Add too little and it may never go off fully, or at least take far too long to harden, particularly if it's cold out. I've done this enough times to get it close enough to right by eye, but if I was mixing a big batch for some reason I'd definitely make the extra effort to get the percentage right. The main thing is to mix it very thoroughly before applying it. Luckily polyester is more forgiving of mistakes than epoxy, and you can easily buy extra hardener if the original bottle runs out before the can of main component.

The cameraman needs to be sacked after taking shots like this, but I think you get the idea. 
Using a clean brush, you coat the area where the patch will go, then place the patch down and dab more resin onto it until it is fully saturated. It's pretty easy to see the difference between dry glass fibres and saturated ones. 
This resin has a faint blue tinge, by the way.

The next steps are pretty obvious - repeat for the next 2 layers. There is no need to wait for the previous layers to dry, just go straight on, making sure the glass is properly impregnated, without slobbering resin everywhere.

So the next morning it's all fully cured and I can flip the boat over again and have a look from the outside.
I sanded all the holes back again, to make sure there was no glass or polyester poking proud of the final desired surface. There needs to be a depression for the gelcoat to go into in order to get a nice finish.
This also gave me a chance to make sure the edges were properly feathered.

If I was trying to do this perfectly, I might clean it with acetone too, but I don't have acetone handy, and as already stated, I'm not a perfectionist.

This is another wonderful piece of cinematography, but again it's important to get the hardener ratio approximately right, and to mix it very thoroughly. This gelcoat repair kit requires a 2% - 3% mixture, but as always, there is a fair margin for error. That said, I'm not as experienced with this stuff as I am with simple polyester resin, and the first couple of times I did it, I added way too much and it went off far too fast.

I quickly realised that I couldn't mix the gelcoat with one hand!

It is optional to add dyes to the mixture at this stage, to try and match the colours and make the repair as invisible as possible, but that's pretty difficult to do, and they aren't stocked in my local shop anyway. There's an alternative school of thought that you shouldn't try to hide the scars on your kayak, that instead they should be worn as badges of honour, so perhaps high contrast colours would be preferable to colour matching repairs. You won't be surprised to read that I prefer that approach :D

This is pretty well mixed now, and ready to be applied to the divots, holes, scratches and cracks.

I ran out of mixture before I filled all the wounds, but that's OK, as a second go over would almost certainly be required anyway.
After a previous gelcoat repair job I noticed lots of tiny bubbles in the repair. I got a tip on YouTube to cover the wet mixture with cling-film to exclude air during the curing process. It seemed to work on my next repair, so I'm trying it again here.
I always put on way too much, but I prefer to build it up well before taking it back again. Obviously that involves a bit more manual work, so I can imagine it would be frowned upon in a commercial setting.

And the big reveal a few hours later. It was still a bit tacky, so I probably should have waited until the next morning before removing the film.

The next morning it's all good and crisp, so ready to start sanding back.

I start with P40 grit sandpaper. This is very aggressive stuff, so I just use it to knock back the peaks that are sticking up.

I almost never sand with just my hand. If I'm sanding a flat surface, I'll use a little block of wood between my hand and the paper. If I'm sanding a curved surface I use a little block of foam. The hand is too uneven and will cause some places to be abraded more quickly than others, and may ruin the work.
If I'm doing some very fine detail sanding, I might just use my finder, but that's very rare for me.

Next up is 60 Grit. This is also pretty aggressive, so I use it carefully with a long piece of foam, but I have a lot of excess material to remove, so it's really necessary.

And lastly (for now) I go at it with P120 paper. After this the surface is pretty much flush, and I can get a good idea of how well the repair went.

So it's pretty obvious that it could have gone better.

There are big bubbles in the major spots I wanted to fill, and I missed out some of the deeper scratches entirely.
Time to mix up another batch of filler and go again.

Once I'd done what I could, I covered the filled areas in cling-film for the night.  The next day it was looking much more promising.

First I repeated the process with the 40, 60 and 120 grit papers, and I could see that the bubbles were gone and all the deepest scratches were filled.

The next stage was to go up through the grits, getting finer and finer every time.

 

First P240, then P320. Starting to look nice now.

Then P400...

...and P600. It feels really smooth to the touch now.

Lastly I go over the whole hull with P1000 and P2000 paper.
For a long time I could never find these really fine sandpapers. I always used to look in paint shops and hardware shops, but they never stocked anything higher than P320. Then someone told me to go to a motor-factor. They stock all the really fine papers for car body repairs - little did I know!

Rubbing the dust off with a dry cloth.

An option now would be to polish it with cutting compound, but personally I think 2000 grit is fine enough.

 

Next up is a wax and polish.

The first step is to just apply the liquid all over the boat with a cloth and leave it to dry for an hour or so.

Then vigorously shine it with a dry cloth. It's not as hard work as it sounds.

I've never done this final step before, but I saw this polishing disk in Lidl recently, and decide to give it a go. 

I had to remove the safety guard from my angle grinder to fit this disk, but I reckon it's safe enough as it has no hard edges.

After that the boat was as slippery as a new-born baby! Seriously, I nearly dropped it turning it over :)

Happy now that the hull was good enough (albeit not perfect), it was time to start looking at the fixtures and fittings.

Even though I hadn't even tried to sit into the boat yet, I could easily tell that the cockpit would be very small for me, so I'd need to fit the seat as far back as possible, and the back-rest wouldn't be going back in. So I decide to fit a foam doubler to the bulkhead to act as a backrest.

I had a piece of foam the perfect thickness, but it was just a bit too small to cover the bulkhead and I wanted to do it all in one piece. I did have a slightly thinner piece of foam that was plenty big enough though.

The first thing to do was make a mould of the bulkhead. I started with a sheet of paper to get the rough outline, then transferred that shape to a piece of cardboard.

This only took a couple of minutes, and another couple of minutes to fine tune the cardboard into an accurate mould.

Then I transferred the mould to the foam.

I scored the outline deeply with a Stanley knife, then followed the line with a fine cut panel saw.

It fit pretty much perfectly first time, but I cleaned the edges up a bit with P60 sandpaper.

Finally I was ready sit into the boat and place the seat.

It was immediately obvious that the seat would have really go as far back as possible, so I marked the outline on the foam bulkhead to cut a recess.

It was also obvious that not most, but all of Ariel's padding would have to be removed.

So I glued the foam and the seat, and repurposed some of the padding to fill the gap between the side of the seat and the hull, to bring the seat side flush with the cockpit coaming, and finally I was ready to take her out for a spin!

As you can see from my review video, I really like paddling this boat, even if the cockpit is very small for me. It turned out that I had to remove that padding at the side of the seat as it was pinching me very hard and making my legs go dead.

I have no doubt that I will have plenty more tweaks and repairs to make to this boat in the future, but I look forward to getting used to it, and it used to me.