How-To: Keel Rebuild – Fix That Hole Caused from Dragging Your Kayak
To start, there are going to be a few things you need:
- – Sandpaper – 120, 220 and 320 grit (or similar grits)
- – Cutters or Dikes
- – A large & a small set of needle nose pliers
- – Steel brush or drill with steel brush attachment
- – Rasp/File
- – Assorted sizes of Acrylic screwdrivers
- – A long skinny metal probe (long flat-head screwdriver works)
- – Heat-Gun
- – Scrap Plastic
- – Cup for water
Most of these items can be found fairly easily. If you need help sourcing some scrap plastic for your repair, contact your local kayak shop!
Take the probe and begin pushing around the visible hole. You are trying to punch through the plastic to find where the plastic begins to be solid again. You may end up adding quite a few more holes around what is visible, but this is okay. It is better to make sure you repair all the weak/thin spots so you don’t find yourself doing another repair in the near future.
Take your wire brush and begin cleaning the surface you will be working on. You can also use a drill with a wire brush to speed this up. The idea is to try and get as much gunk off of the plastic to have the best bonds when you put down fresh hot plastic.
This does not need to be perfectly clean, but try your best to get all the really gunked up areas.
Now we will start with the weld. Turn your heat gun on and let it warm up. It is important to remember that once you start, you need to keep going to keep the plastic from cooling down. Take a piece of your scrap plastic and use the cutters to cut it down to manageable size, depending on the size of your hole.
With the heat gun warmed up, start warming up the plastic around the edges of the hole in your kayak. Make sure you do not get the heat gun too close to the plastic until you have some experience with how hot it gets. You can easily begin melting your kayak more than you would like to.
If plastic starts melting too fast, have a cup of water ready to pour over the boat and immediately cool it down. Once you have the edges of the hole warm and pliable, move on to the next step.
Take your large needle nose pliers and grab the piece of plastic you have cut for your hole. Begin warming the plastic up with the heat gun. Once it starts to become pliable, begin twisting and rolling the pliers to make it into a small ball of plastic.
Once the plastic is soft, hot and in a small ball, use the heat gun to heat up the surface around the hole in the kayak. Once the plastic starts to look glossy from the heat, use the pliers to stuff the ball of plastic into the hull. Work the plastic around in the hole with the pliers as it cools to fill the hole.
Repeat this step until you have all the holes covered up with plastic. On this portion, it does not need to look pretty, we are just trying to fill the hole so we have a good foundation to start our weld.
After you hole is completely filled with the melted plastic, we will start with the welding technique. We will need the heat gun and largest acrylic handled screwdriver. The acrylic handle is able to withstand the heat better than a plastic handle, to keep it from melting on you while you work the hot plastic.
Heat up the plastic around the edges of your recently filled hole. Once it starts to look glossy and you are able to make small indentations with your screwdriver, take your acrylic-handled screwdriver by the driver side (handle way from you), make a quick down-twist-up motion where the new plastic meets the plastic on the kayak. You do not want to keep the handle on the hot plastic too long or it will start to stick and melt.
Work around the entire edge of the plastic. You will need to keep adding heat to keep the plastic from cooling.
Again, we do not need to make this part pretty. If you discover some weak spots or holes after doing this, repeat steps 5 & 6 again.
Now we can let the plastic start cooling so it will harden up. If you start to see swirls in the edges of where the new plastic meets the old plastic, it means the plastic is bonding well. You do not want a bunch of straight lines where the old and new plastic meet, because that can lead to a poor weld and more issues with leaking.
Take your rasp and begin shaping the hardened plastic. Be mindful of where you are in the plastic and try not to go too deep. You are aiming to make everything smooth and follow the original shape of the keel.
Once you take the larger plastic off with the rasp, use your file to take the finer bumps out.
Grab your 120 grit sandpaper and begin working the entire area around the new plastic. You can fold and wrap the plastic around the keel to help make better contact.
It is okay if this scratches up other areas on your kayak. We will show you have to remove those as well.
After you sand the area with the 120, move onto the 220 and repeat the same process. Once sanded well with the 220, wipe away any plastic dust and check the edges of your weld. The sandpaper can help show you where some of the edges might have not been bonding so well. Move to step 9A, if not , move on to Step 10.
If you have edges that need to be reinforced, use the heat gun to heat up the edges of the plastic and smaller acrylic handled screw driver with the down-twist-up motion until all the edges look welded together nicely.
Let that cool and then repeat Step 9 until all the edges look like they are bonding.
Take the 320 grit sandpaper and run over the entire section you have been working on until it feels smooth to the touch. Make sure to hit any areas you may have scratched with the other sandpapers. It will smooth out the larger scratches and we can remove the small ones easily.
Once the entire area is smooth and has been sanded with the 320 sandpaper, grab your heat gun and move it around to any areas that have scratches on it. It will only need a few seconds of heat for the scratches to disappear.
After you have given some time to cool and harden, you can add some water inside the hull with the front of the kayak lifted higher in the back to check and make sure you do not have any leaks before taking it out on the water.