The material from which many plastic canoes and kayaks are made is called high density polyethylene (HDPE) and is an extremely difficult material to repair. The same chemical properties that make your boat extremely flexible and durable also prevent other materials from adhering to it.
HDPE is resistant to repairs using typical adhesives and sealants in most applications. However, this does not mean that scratches, cracks and holes in plastic kayaks can not be fixed.
Let's discuss some guidelines on how to repair each type of damage you may suffer throughout the life of your kayak.
Scratches and scratches on kayak helmets
Scratches and cracks are the most common damages to plastic kayaks. The kayaks are dragged along the coasts and rowed on shallow rocks. They also hit on numerous things as we take them from storage to the top of a car.
Scratches are part of the sport and, for the most part, they are nothing to worry about. Some of these scratches accompany the peeling or fraying of the plastic. These plastic shavings are not a problem either.
If there are thick scratches that detach the plastic, you can simply take a razor blade and cut out those areas.
Sometimes, the perforation may be deeper than normal and it will be big enough to worry you. In these cases, the plastic can melt by dripping into the crack to fill it.
The best plastic to use is the same kayak plastic as any cut-out you have saved or other repairs you have made in the past.
Otherwise, you can buy HDPE welding rods from many rowing stores. You can even use containers like milk cartons that are made of HDPE.
Simply take a lighter for the plastic and, as it melts, drip. Allow these drips to fill the scratch. Use a spoon or screwdriver to spread it in the slot. Sand or trim any excess and carry out the repair without problems.
Holes in the upper part of the kayak
While it is rare for the top of a kayak to develop a fissure, holes are quite common due to all the things that are screwed into them. When the screws are lost or the accessories are removed, a hole is left and when the water splashes, you can enter the kayak. Obviously, you would not throw away a kayak in these circumstances.
Something as simple as the insulating tape will keep the water out. It will only need to be replaced regularly, but it is a decent temporary solution.
A UV resistant silicone can also be used in this situation. These can be found at hardware stores and are usually labeled for 'marine' use. Use adhesive tape on the bottom of the hole to act as a temporary base, then fill the hole with the silicone on top.
Cracks in HDPE Kayaks
Cracks are the most serious damage that can happen to a kayak and location is everything. Many cracks in the top of a kayak can be handled in the same way as a hole, either with adhesive tape or silicone. While no solution will solve the crack, both will prevent water from entering the kayak.
It's a completely different story if the crack is at the bottom of the kayak. This is the side that supports its weight, hits the rocks and prevents the boat from sinking. Unfortunately, this is also where cracks occur most frequently and require serious attention. The kayak should not be rowed until it is removed and controlled permanently.
The most serious location for a crack is under the seat and forward to the pegs of the foot. This is the area where the weight and strength of the rower is most often exercised unevenly. The cracks towards the bow or toward the stern are less serious. These areas do not have the flex that the seating area has, although they are still a concern.
Regardless of where the crack is, the ends of the crack should be drilled to prevent further propagation and the cracks should be plastic welded. If you are going to have a professional do this, leave the piercing to them.
Consult a kayak store or rental business to guide you in the following steps. They will evaluate the severity of the crack with respect to its size and location. When looking at the size, they will verify not only the length of the crack, but also its opening width. Obviously, a huge opening is more serious than a thin crack.
If you are going to try the repair yourself:
Using a small drill bit, make a small hole in each end of the crack so that it does not extend.
Plastic welds the crack to complete the repair. You will need a plastic welding kit with HDPE welding rods and it works similarly to a glue gun.
The plastic can also be repaired with a lighter or torch and plastic debris.
When you try to repair a serious crack on your own, you risk further damaging your kayak. It is also possible that what you do is not repairable by a professional. Think carefully before you begin and proceed at your own risk.
Here we have a video (in potugués) explaining the step by step:
