I already built the main mast step as specified by Brion Toss, but there is no room for an 8" mast in the galley. So I did some research and decided to install a deck stepped mast instead of a keel stepped mast. A deck stepped mast will be set on the deck. This allows me to make a hinged mast support so it can be taken down easily. This also eliminates problems with possible water leakage around the mast where it enters the cabin.
Here's what the mast step looked like last year. I spent hours building this...	Major problem, looks like the main mast if stepped on the keel will take up too much space from the galley. Plus trying to step up and over the mast step every time you go into the galley and trying to squeeze my large form past the mast.
Here is how we start again. I will need to install a metal support plate here to accomodate a heavy duty jack post.	This is how the ceiliing looks. Too bad I cut the damn hole. I'll need to remove everything and install new wood.
First I found piece of old growth fir and made a round ring to fit up inside the cutout. 1 1/2" thick and 12" in diameter.	All glued into place ready for filling in the rest. The bolt through defines the exact center of where the mast will be stepped on deck.
Next plug to put in. It has to be retangular to allow for it to sit on the deck boards.	Spent all day working above my head cutting out the shape. The gaps look wide but the sides taperin for a flush fit at the top. The jack post will fit under this board.
Jack post roughed in to see how it will impact the galley. Looks good, lots of room around it.	I will have to install a bigger base plate and have the new post welded to it.
The stock plate should work out fine for the upper end.