Sealing mast compression post

[WaldPinkler]

I've dug down into the bilge and the mast compression post looked wet. I wanted to check for any corrosion.

There was a thin layer of fibreglass around the bottom of the post and a weep pipe with disgusting black filth oozing out.

I knocked the glass off and the weep pipe was just half a piece of pvc sitting on the stainless plate that the post sits on. There was oily water between the glass.

No corrosion at all.

What should I do to now? Ideally I think the post shouldn't sit in the bilge water but I'm not doing anything crazy. How much of this glass should I remove? Perhaps the water is also under the metal plate. Should I recover the post with glass or leave it bare?

[WaldPinkler]

There's a smaller step further back that looked like it was something under the glass. I drilled a hole, no moisture just some lead with 5mm of glass covering. Perhaps the same at the post but I can't be sure.

[rbk]

I would simply find the edge of the plate and with a small drill bit see if you can angle drill under the plate and see what’s under it. If dry wood, fill drill hole with epoxy and leave the plate exposed (maybe seal the edges to prevent water ingress) but leave that plate and base exposed assuming they’re welded together. Both look to be stainless and should be left exposed, sealing them up only invites the possibility of crevice corrosion. If it’s simply a steel plate resting on your keel do the same above.

[WaldPinkler]

Post isn't welded to plate.

[Bowdrie]

Originally Posted by WaldPinkler

Post isn't welded to plate.

How big is the post?
So, the post just sits on a metal plate that was put-in when the fiberglass was layed-up over the lead ballast?
With the lay-up still wet, the plate could be pushed down into the glass to hold it in position?
Then some glass was used to "encase" the lower end of the tube to hold it in position/keep from shifting?
No upward strain was envisioned for the design beyond that which the fiberglass bond could take?
What do you want to do with the post?

[WaldPinkler]

It's a 100mm pipe. There's a hump where the plate is glassed over. 5mm thick glass. Yes, there was a single layer of glass going up the post a little which trapped water when the bilge filled. I can make an exploratory drill hole later near the plate but it's a little wet down there and I have some other jobs to do rather than epoxy filling today.

I removed the tanks and thought I'd look at the post while I can access it. I don't know what should be done. There were other idiotic things done with stainless like the tanks sitting against the hull catching water and corroding and chainplates glassed over inside trapping water.

[WaldPinkler]

Actually, there's something inside the drainage hole at the bottom. I'll have to get my camera down there to see if it's somehow mounted or just some resin caught in there.

[Bowdrie]

It would appear that for now just keep an eye on it, with more serious work and or changes you may need to pull the stick.
I don't like the idea of the lower end of that tube free to float around with only rig tension to keep it from "scooting" if you will. If it scooted off that plate the rig compression loads might drive the tube through the thin laminate, big problem.
Your concern is to keep the metal dry?
If so, the tube will need to be shortened so that it can be bedded/fastened to a glassed-in structure that is above the bottom/bilge water.

[WaldPinkler]

My concern was more that I pulled the original glass off and I had better fix it without any tanks in the way to access it. I could glass over it again. Even epoxy coat it going higher up but moisture has its way of getting into things and I've learnt enough about crevice corrosion with the chain plates.

[Bowdrie]

Covering up everything with glass/epoxy is not necessary.
With a little handy work, the tube can be restrained in movement without glassing the bottom.

[chasfgr]

33 years ago, when I was looking for my replacemnt boat (still with me) I specifically looked for a keel stepped mast.
Most boats including later models, had a deck-stepped mast - cheaper and easier for the builder.
I did have to drill drain holes in the mast, for the water inside.
The through-deck gaiter alwayd leaks, but easily dealt with as it end up in the shower-tray.

[Don C L]

IMO you may have made a problem where there was none. The glass there was there to hold the base from moving and the PVC drain was there to drain any water in the mast into the bilge. The black gunk coming out was probably just typical bilge gunk. You could rebuild it the way it was or you could look into fitting a shoe in there. At least you know now there is no corrosion in there!