soaked gunnels

The gunwhales were to be fitted with safety rails in the OP. Is the PVC strong enough for that application? Hard to say without seeing the rails, I'd guess.

I'd be a bit wary of plasticised PVC for bonding, the non plasticised is OK and can bond well.

 

It's worth a thought SS.
I was thinking that a lot of gunnels are hollow,probably formed in the moulding,and get their strength from the thickness of fibreglass.
I could use roving,and form the same sort of thing,and with the PVC box section used as a former,which wouldn't need to adhere to anything,it should be strong enough to take the rails etc.
Depending on the finish,I could neaten it up with f/glass tissue,and sand it to look decent.
I've raised the transom sides either side of the engine,mainly to stop it taking on water when launching it and for when I throttle back in a following sea.
I'll take it out on test before I fibreglass it,and if I am satisfied,I'll keep it,if not I'll finish it off and sell it with a 5hp Yamaha engine on it.

 

PVC can be bonded, after a "caramelizing" treatment with a torch. I'd use solid stock, instead of hollow and I also wouldn't 'glass it over, just hard fasten over bedding, so it can be removed later if necessary.

 

I don't understand what you mean about Hard Fastening over bedding.
The present gunnel is already 2.5" square,which is fibreglass over timber.
Do you mean you would remove it completely?(it's external)

 

Are we talking about a gunnel or rub rail?

 

It's the 2.5" square box section formed in fibreglass that is on the top edge of the hull and forms and stiffens the shape.It is on the outside of the hull.
There is no Rub strip incorporated in the design of the hull.
The gunnel is formed around timber which is soaked with water.