Repairs

I recently had a less-than-majestic beach dismount with the swell breaking right on the shore. This left a hole in the side of of the ski, behind the cockpit,  a broken seem,  and a fracture from one side to the other. Also, the bottom of the boat after of the seat,   (which was already soft from a loose stringer) can now be buckled inwards.

Now, this boat is on the older side and has had a history of being dropped and abused by  previous owners, so I don't want to spend the money to have it professionally repaired.  What I am interested in, however,  is using it to practice on to repair other skis I have and, if possible,  make this kayak seaworthy again.

So my question is: where do I begin?

Well you never mentioned how long the piece of string was?
This is not such a simple question. People think they can just repair fiberglass because? I don't know why? Nobody attempts to repair their cars after an accident where they have essentially bent the chassis.
You have a life saving device you are trying to repair by essentially guess work. You may not want to go into the ocean again as you know that what you have done could be sub standard, but the next person the ski is sold to has no idea and ventures many km's into the open ocean and then the ski lets him down?
I have a $20,000,000.00 insurance cover for this same issue, it costs me a ton of money. However I try not to guess how to make the ski structurally sound, loosing a life in the ocean cannot be paid for by any amount of money. I will never repair something that I know will be sub standard and not fit for use. A surf ski has to be able to go into the surf!
Rant over!
Well, first port of call is to make the ski structurally sound.
Stringer damaged? Cut the ski open and repair the stringer. Repair all the hull damage from the opening you have cut on the inside. I could go on, usually I would charge in the region of $1000.00 to repair a ski that is essentially in half.

You are a grumpy sod, Ranga, but I bloody love your posts.  

Everything you have said makes perfect sense. Modern composite skis aren't just a layer of fibreglass; they are a true composite with a core. Rigidity depends on the core being solid and not compressed; a bit like cardboard boxes. Fairly rigid until you crush the waffle bit in the centre; then the cardboard is as bendy as paper.

Buckling damage indicates that the core has been crushed. I can only guess that fixing that either involves removal and replacement of the core, or some sort of injection system. This would be complex work requiring knowledge (very expensive stuff, knowledge) and the right tools.

After reading these posts, I suspect I am coming from an opposing end of the sport.
 
I bought this particular ski knowing that it was a beater that I was going to use to train on, alone. I also knew that I was only going to use it close to the beach, in flatwater conditions and that  downwind runs were probably out of the question. If the boat were to break in half, I am, at most 300 m from shore. Even the day when it got caught in the surf, it was  calm with only a sea swell coming in that broke on the shoreline.

I think there is a place for using these kinds of skis, especially for training sessions or when using on pebble and stone beaches close to the shore like I am. If they get a soft spot or a ding, you can patch it up with some carbon fibre or fiberglass. It won't be the prettiest of repairs, but it will be good enough. 

Because of the extent of the damage on this boat, I know that it is probably a bit more complicated than draping a sheet of carbon fibre over hull, but not much. But after realizing how easily damaged surfskis are it makes perfect sense (to me at least) to try a DIY repair when there isn't much to lose.

As long as you dont sometime in the future flog it off as a cheap ski for someone else to learn in