Modern plastic kayaks are pretty hard wearing and tough, designed to take a bit of a beating. Despite this they still take damage every now and again. Scratches and dents are pretty normal when your running rocky rivers, sometimes you might get a crack or split. Either from taking a big hit or just lots of wear and tear.
These are somewhat more of an issue, a split could cause a leak or even weaken the overall structure of the boat.
There are a number of ways to fix a split but the best way to do so is with plastic, this fills the gap and helps bring back a bit of structure (but not all the way, once you have one split you increase the risk of other splits.)
One way of welding is with a heat gun, the risk with this is holding it too close and damaging/ weakening the plastic around the split. For this reason i prefer using a soldering iron.
Step 1: Pulling Out Your Outfitting
Most splits happen under the seat area or the boat. This is because this is the widest/ weakest area of the boat, and also the area that usually takes the most hits (along with the nose).
This normally means that you have to rip all the outfitting out before you can get to the inside of the split.
It can be kind of a pain in the arse, and usually takes longer than the actual weld.
So: start by pulling out the back band, any junk you have in the back and the seat.
Then you need to make sure the inside (and outside) of the boat is clean and dry.
Step 2: Cleaning
As the split i was repairing had already been welded previously (it held up for 2 years) my step at this point will differ from that of a 'fresh' split. So ill include both parts.
The first step when dealing with a new weld is to drill a hole in either end of the crack. This will stop it from spreading any further next time you use the boat.
Once you've done this you may want to use a knife to clean up the edges of the crack so its easier to get plastic into it.
Repairing a weld:
All of the stages above should already have been done if you are repairing a weld that has cracked. So the only thing to do here is to remove any plastic that remains from the original weld.
After all of this you should have a nice clean split ready for welding.
Step 3: Welding
As i mentioned before i'll be welding with a soldering iron, mostly because its what i had on hand, welds can also be done with a heat gun.
I tend to carry a few pencil sized sections of spare boat plastic in my kit bag (my soldering iron also lives in there). These were cut from a wrecked hull of a boat 'donated' (dumped) at our campsite last summer.
***Obviously we are going to be burning/ melting plastic here so you need to be somewhere well ventilated and maybe wear a mask if you feel the need***
This stage is pretty simple. Hold the soldering iron in one hand and the plastic in the other. Melt the tip of the 'pencil' and drip the plastic into the crack. Try to get the melting plastic as far into the weld as possible, you can use the soldering iron to re-melt the plastic as it fills the crack to smooth it out and get it in deeper.
Don't worry about any overflow, we can deal with this later.
Do the same to the inside of the boat.
Step 4: Sanding and Finishing
Now to get rid of all that overflow. Its as easy as sanding it off.
You don't want to sand so much that you thin the boat but you do need to get it smooth. You don't want any edges to catch on rocks, or anything like that
Just to make sure we're going to cover the inside weld with duct tape or something similar.
Now you've got to get all your outfitting back in, and in the same place that you took it out (easier said than done).
Finally go kayaking again. And as always have fun.