Land N Sea Roof Rails

This is a zamak stanchion base on my 40 year old boat. It appears to have machine screws holding it in place. And a pop rivet securing the stanchion to the base. 

The roof rail seemed quite secure despite a couple bases showing corrosion/cracking as pictured above so up to this point I haven't been inspired to look into addressing a fix. Now that I'm taking the dinghy with me on Big Duck, and need to pull it up over the rail to get it on the roof I thought I'd better make sure this stanchion base didn't let loose.

I'd redone stanchion bases on the fore and aft decks and learned that the machine screws wouldn't easily come out -- I'd broken all but one trying to get them out. I found several of them cut off at the deck under some of the not original bases confirming that I wasn't the first to have this problem.. I generously applied penetrating oil to the fasteners with the cracked base on the roof and waited overnight.

The next day I got my butane pencil torch out thinking a little heat might be necessary, but before putting the flame to the Phillips heads I thought I'd give them a gentle nudge with the screwdriver. Much to my amazement they would all turn...a totally different scenario than with the other bases I'd replaced.


Well, the fasteners would turn, but they wouldn't come up. I worked with them and eventually removed all three. They brought up wet foam with them -- no wonder they weren't hard to get out!

So with the fasteners out, I tried to raise the stanchion by prying under the base with a large screwdriver, hoping I could get it high enough to remove the old base and slip the new stainless base on. Nothing doing - not the slightest movement. I then 'tested' the stanchion by wiggling it to and fro to see how loose it was - again, no movement.

OK, maybe I'd just somehow put in new fasteners. I tested the hole with a straightened clothes hanger. It was at least 3" deep, but the rod came up wet and there didn't seem to be anything substantial to take a fastener. I probed another hole as well, to see if there might be some wood or metal I could get hold of with a fastener at a slightly different location. I was unbelieving at what the probe brought up on the third hole. It was a pliable rubber cup that was the home for the machine screw threads! Maybe a previous owner filled the hole with silicone and stuffed the screw in? Then it dawned on me.

This zamak base was solely to keep the rail from coming up. That fastener was doing essentially nil. The stanchion itself was firmly embedded 3" into the foam roof. Even though the foam was wet, it was solid. At this point I decided I might be able to make this base look better, but it really didn't need to be made more secure. Whoever designed this boat was a genius not having anything in the roof to rot.

As long as I was this far into it, I decided to poke one of the holes through the inner liner - into a cabinet above the galley. I used a piece of stainless all thread and a starboard block below to fasten to a Bimini bracket above to prevent the stanchion from moving up.

The allthread runs down into the galley cabinet.

This is the view from inside the cabinet.

 I'll give her a few days to air out, then seal the holes and spaces under the stanchion base. The few drops of water that came out when I punched through the liner into the locker might upset some folks but it doesn't bother me a bit.