Whilst it would be nice just to be able to screw the new deck gland straight onto the coachroof, at only 9mm in thickness the plywood is just too thin for this to be an option and I have to use bolts to achieve the fixture.
Here you can see the bolts poking up through the coachroof. Now this will do the trick, probably, but if there is a slight ingress of water it will seep into the plywood. Despite it being Marine Plywood and therefore waterproof, that is the glue is waterproof, that doesn't mean to say that I want water getting into the wood as it will still rot.
Where the cables go through the deck the edges of the hole will be coated with neat epoxy which will soak into the plywood and prevent any water from getting into the wood by forming a waterproof barrier over the inner surface of the hole. The bolt holes are more problematic.
But there is a tried and tested way to fix this.
Firstly you make the bolt holes oversize. A lot over size. To do this I used a 12mm flat blade drill bit from the inside first about halfway through the wood and then from the outside to give a neat hole with no tear-out on either side.
On the inside of the cabin a small, thin piece of wood, wrapped in plastic, is forced against the inside of the coachroof. The roof is curved but the thin wood deforms to fit the curve and create a seal.
The lower end of the prop is rating on any suitable surface that is slightly too big, forcing the wood hard against the ceiling.
Finally, or finally for this stage of the procedure, the cable hole is coated with neat epoxy and the three bolt holes are filled with thickened epoxy and all is left to cure.
The final part of the mounting will be carried out once the epoxy has become hard.