Mast support- for-aft-inlayed beam

Hi all,

Just a quick question if anyone has done this too.

A few months ago, my mast broke during a storm and the mast step had some damage that I now try to repair. Before, I already noticed that the elevated area on which the maststep is mounted was sitting lower and it sounded hollow.
Furthermore, inside the cabin there are a few obvious areas where there is delamination, which I also aim to tackle.

Today, I cut away part of the top lamination to expose the beam, which indeed was delaminated and a bit wet, but to more of my surprise at the fore end there is a big open space, through which it seems the water is likely to flow to the bottom part of the roof.

Anyhow, a picture can tell you more than words, so I attached two.

My question: do you agree that this open space needs to be filled?
Would you agree that I fill it with thickened epoxy, close everything up, and the tackle to delamination from the inside of the cockpit?

Thanks so much,
Bobby

Bobby Koeleman wrote

I already noticed that the elevated area on which the maststep is mounted was sitting lower and it sounded hollow.
Furthermore, inside the cabin there are a few obvious areas where there is delamination, which I also aim to tackle.

Given that you say you were aware of the same delamination problem inside the cabin, I am surprised that you chose to remove the top of the cabin as that will take much more work to make a good repair than would the exposed chopped strand mat on the underside of the cabin roof. But it's a bit late for me to tell you that!

I would guess that it is all part of the same problem. Somewhere there has been a long standing leak that has saturated all the balsa wood sandwich in the roof and the mast support beam. As your earlier photographs show nothing more that the cleats and mast step on the cabin roof, I'd suspect one of those to be the source of the original leak.

I have never seen the mast support beam exposed but I would suspect that the gaps you have found indicates an earlier very poor repair that failed to do what was needed.

My question: do you agree that this open space needs to be filled?
Would you agree that I fill it with thickened epoxy, close everything up, and the tackle to delamination from the inside of the cockpit?

Yes, that space definitely needs to be filled completely with strong hardwood timber.

Given that I suspect it is a single problem, I would open up the cabin roof before doing anything on the outside. With GRP it is always better, if you can, to apply all the resin in a single process rather than allow one part to set and then add more later.

Think how the cabin moulding would originally have been made. The mould would have been upside down, gel coat would have been applied, then a lot of fibre matting which would have been wetted with resin. After that a good quality timber beam would be laid in wet resin in the recess, then more resin and matting laid on top. That process would have filled any gaps and completely encased the mast support beam in GRP, keeping it separate from the Balsa wood sandwich in the cabin ceiling. In all probability, the balsa wood sandwich would have been laid and topped with matting and resin in immediately afterwards as part of the same process.  I think you need to replicate that as closely as possible.

Thank you Greg, for the response and tips!

I had to open it up from the outside, because the lamination on top where the mast step was, was damaged and the whole area was sitting lower; damage that occurred when my mast came down. Perhaps I could have tackled it from inside, but too late now and I will rebuild everything like you describe; thanks also for outlining the process!

Indeed, I will proceed from the inside now, and will post the progress.