Deck to Hull Joint - Which Bolts Are Critical?

[BoatingBeginner]

My early 70's motor boat has a deck/hull joint akin to a biscuit tin or shoe box.

The 'fender' on my hull is/was black-painted wood D-section and base - both probably oak - which has rotted beyond repair. I'm removing all the wood and replacing it with a rubber D or B-section.

Having removed a section of the wood, there seem to be three sets of bolts. Increadibly, those holding the bulk of the wood (the D-section) were made of mild steel and some have rusted to virtually nothing. Then there is a set of stainless bolts which held on a base strip of wood. Having removed this (rotten) base, these now stand proud. Finally, there are a set of stainless bolts lying flush to the rim of the deck. Only the bolts lying flush are precisely spaced (about 16").

All the bolts seem to go right through, and all the nuts are glassed-in on the inside and access is very limited in places, so I'd rather leave all of these be.

The question is, would it be okay to cut off all those bolts standing proud, and leave just those 16" apart (marked with green arrows in the last picture) to do the holding? The gap between hull and deck will be cleaned out and Sikaflex rammed into the gap.

 

[catalac08]

If there is a gap in the flange between the deck and the hull I would be inclined to clean out the gap using a dremell or similar tool and then use thickened epoxy resin to strengthen the hull/deck joint as best you can.

With respect to the other bolts which form the structural hull/deck joint. They would need to be a lot tighter than you would wish to bolt down onto a rubber D section so I do not think it would be wise for you to try and use the hull/deck joint bolts to fit the rubber D section.

I think you need a new separate set of screws to fit the rubber D section, which unfortunately means that you have to access the inside of the hull to glass in the nut heads for this, unless you can get out the old bolts and re-use the existing glassed in nuts?

A pig of a job to do it properly-you could fit the D section using big self tappers but then how do you seal the holes satisfactorily.

Good luck with it-I am sure you will quickly get lots of helpful advice.

 

[BoatingBeginner]

Thanks for your thoughts - I was going to fit quite a tall, low-profile rubber-section, like this (which just happens to fill the gap left by the wood)...

I'm thinking that on a good, clean surface, it should only require some Sikaflex as adhesive, and no screws will be needed (except at the ends to prevent lifting off) - so I'm not looking to re-use any of the existing bolts. I just need the ones by the green arrows to be sufficient (?) to hold the deck to the hull. The rest can be ground off, with the mild steel bolts rust-treated and sealed over, leaving a good flat surface for the rubber.