H25 Mast-step R&R
The other two fasteners are lag screws going into the top (end grain) of the compression post. You will have to back out these two and remove the compression post (it's just screwed to the bulkhead) to get a full look at this. The bulkhead will not be affected by this operation-- but this would be a very good opportunity to check and see that you do not have any crushed deck core here. If you do, see my older (archived) posts (or my blog) about the easy way of filling rotten core material.
Given a sound deck structure, be sure to re-bed the mast-step plate/tabernacle with 5200. This will provide the necessary shear (side-to-side) resistance, keep out water and assist, if ever it happens, to keep the mast connected to the boat in the event of a rollover. Anything less that 4000, 4200 or 5200 is asking for future leaks. Besides just wiping with solvent, rough up the deck under it with a sharp scraper or 60- 80-grit paper.
When you reassemble this, use a decent backing plate under the forward two screws-- not just fender washers. This will stiffen the deck-- because most of the mast base is forward of the compression post (which is really just there to stiffen the bulkhead). I used a scrap piece of vinylester fiberglass plate; but aluminum, stainless (if you can drill it) or thoroughly epoxy-impregnated wood will suffice.
Also, dribble a bit of epoxy down the after two holes to get it into the end-grain of the compression post (not too much or it will overfill and drip into the main cabin). This will 'seal' these holes; and if the epoxy hardens on the threads you can always back out those screws by applying a solder-gun tip to the metal for a few minutes.
You might consider putting in the forward two screws upside-down-- with their heads down and the nuts under the mast. It won't make any difference in how it all works and you won't have screw-end threads poking down into the head to bang your head on. Use new nylon-insert locknuts and machine screws-- of 316 SS if possible. You can get new lag screws in 316 as well.
Usually the wire-connection plug is poorly installed by owners, not by the factory. I have seen them in with silicone-- which is very bad, especially in this area. Remove the fitting (and buy a new one, like one in stainless from Sea Dog or someone) and scrape the deck area clear, thoroughly ream out the old hole and fill it with epoxy. Put a piece of duct tape over the bottom first to keep it from running through. When it's cured, drill a new hole through it and bed that thing down with 4200 or 5200. Don't use anything less in this vital area of the deck, no matter what the fitting is for. Silicones and other excuses won't keep water out for long. (You can always break a 5200 bond with a hammer and sharp chisel. I have made a living doing this for decades!)
The same goes for any halyard turning blocks, etc., in this area. NONE of these should ever be fastened through the hatch shroud and deck together, as there is no way to keep the deck holes properly sealed from the outside. (This is what rotted out my boat's deck core.) If you have halyard turning blocks, consider a base plate like those at Garhauer (which I used) or DAMCO (which I didn't use because I wanted holes forward and aft too) and, while you have the mast step off, install it. Then, fill the old holes with epoxy.
