Boat hull crack

First let me be clear that I am not planning to fix this crack myself.
We will have a professional repair it for us.
I'm only interested in finding out what may have caused it and how it should be
repaired for the sake of gaining some knowledge on glass repairs.
The boat is a Whaler 25 build in 1988.
We bought the boat used some 10 years ago and we're now prepping for
renewing the boat completely.

 

It's hard to tell just from the photo, but that crack has been there for quite a while. The dirt and mold in it are an indication of age. It could have been an impact or have started with delamination from hard use.

 

The rail shows some deformation, which is indicative of an impact. This means you'll have some delamination and foam separation, between the liner and hull shell, which is very tough to repair on that particular boat. Considering the value of the boat, the other likely issues BW's have of that vintage, you might want to do some hard thinking about the repair. To do it right, you have to inspect the condition of the foam to hull shell/liner bond, which is exceedingly difficult. It's very probable the crack has permitted moisture to get in, which has condensed and collected at the bottom of the voids, making it impossible to remove without major surgery. This is all before the crack is fixed. Lastly, don't let the "pro" tell you he can make a good repair "all from the outside", as this is a Mickey Mouse fix and you'll likely still have other issues to contend with.

 

I'm with PAR on this having repaired a few Dell Quay Dory craft. It is repairable but a lot of attention must be paid to the water ingress into the internal foam. This does not easily dry out (if ever) so it needs to be cut out down to dry solid foam. If you are lucky only a few mm maybe 25mm (1") or so is saturated. I tend to replace the foam with epoxy and microballoons, then build up the glass laminate and finally gelcoat. You will also find any piercing screws, not into blind water tight ends will let water in as well. Don't ignore the motor mount holes either as these can allow water to saturate the transom ply, if the BW is like the Dell Quay offering. So check all this before you commit to repair.

It is also acceptable to bond in new foam strips, timber etc inside the hull as packing replacing the original foam core. Depends on how bad the saturation is and whether you wish to strengthen a part.

If the boat is way too heavy, that also indicates water getting into the internal foam. Be ideal if we could dissolve the wet foam, drain and refoam after drying but that is not yet possible, although quite big areas can be done it is expensive unless you DIY it.

As for what caused the crack in the laminate, could have been pretty much anything, a knock from a piling in a seaway, collision with another craft ? very hard to say. As to whether the boat is worth saving and repairing, that depends on it's value probably more on engine age/type. To give some idea this year a friend bought a similar vintage 13' Dory no engine or trolley/trailer for around 300 dollars US. It was basically sound and required modding to certain other operational requirements but still needed over 100 holes filled, some floor repair etc etc. However it will give at least another 15 years service. Key thing was finding 99% dry foam as the boat was stored out of the water under cover most of the time.

 

Might not be too bad, after all it is well above the waterline, in a less critical area.

 

Thankyou for the replies guy. I really appreciate all your help.
The expert we asked has been restoring boats since well before I was born.
He has worked on almost every single boat at our yacht club.
The crack does sound like a more serious problem than I thought at first.
I will keep all your conclusions in mind when we'll talk with the expert.
I do hope the foam isn't too saturated. I don't think so either.
We still get a WOT of 42 mph with twin 130 hp e-tecs.