Thanks David! 

All makes sense to me.

So my plan as of now is to install the main bulkhead, which already has a beam on ether side of it. This beam runs across the entirety of the caben, from port to starboard. (Originally was the main suport for the Bermuda rig). forward of that, I will glass in the forward bulk head.

This head will take the shape that David has recommend. The only difference is that it will be taken down to the floor of the caben floor. It was originally 1/2 in ply but I will laminate that with 3/4 ply on ether side. The 3/4 ply will come  to the Midway point of the hull. (As pictured in the example).

In between the two bulk heads is where the head and a hanging closet are. These will be reinstated with 1/2 in ply forming the "doorways". The doreways are about a foot and a half from the center of the mast partners. The combination of the two bulkheads (forward and aft), and the doorways (port and starboard), form a rectangle on the caben ceiling. This rectangle will be reinforced with three pieces of laminated 1/4 in ply. 

Above deck, three more pieces of 1/4 in ply will be mounted.this will be the same shape as the rectangle on the ceiling of the caben. The post to receive mast shims will be above that, "Four pieces of 3/4 in ply rings". These will be bolted through; the three pieces of 1/4 in ply above deck, the deck itself, the three pieces of 1/4 in ply below deck.

It should all be less work than it is writing it down. I just wanted to say it out loud on the internet so I can start the process with some peace of mind.

Thanks to anyone who understands.  Hahahaha 

Hotdog

A David.

That is a very helpful picture. I'm thinking of incorporating that consepet onto my bulk  heads witch sit about a foot for and aft of the mast. I don't know it that is a head liner in the image you posted? I have a liner in my boat And was wondering if you would recommend removing it or just callk over that part? Also what is the stuff you used in that picture to adhear to the coach roof 

Scott Dufour wrote:

On my first dark and stormy night, I'll look at those mast partners and whisper, "David said it's okay.   David said it's okay"

I see less need for additions here. Some boats with unstayed masts seem to creak a bit under rolling conditions, indicating a lack of rigidity athwartships, but fore and aft they are naturally stiffer. I agree that the mast sees considerable loadings when running in a confused sea, but the hull and deck themselves seem able to cope. So many GRP boats have now had unstayed masts added with just local reinforcement of the deck in way of the mast that there seems little need to worry unduly. OK, we all have memories of the "dark and stormy nights" we've been through, when we've wanted the integrity of the boat to be completely beyond doubt; but in this case, I think extra reinforcing is just to enable us to sleep sounder o' nights. Not a bad thing, at that.

That make complete sense.  Thank you, David.