Bedding cabin top mast step

[hriehl1]

Maine Sail has me sold on the virtues of butyl tape (in fact, he sold me some too) for ordinary bedding purposes.

I have a substantial (3/4-inch-thick, probably 5 inches by 9 inches) aluminum (??) casting that serves as the cabintop mast step, and that casting is through-bolted over a bulkhead directly underneath.

My question is the appropriate bedding agent for this mast step application. Given that (as I understand it) butyl never really "sets up", I fear the immense pressures in this application would literally squeeze-out all the butyl. Perhaps something else that does "set up" a bit would be better?

Thanks for any insights.

[Skipper599]

Hey, glad you asked that question because I was wondering the same thing as I'm about to install a mast step myself.

[Sailmachine]

Could you not counter sink the screw holes and chamfer the edges of larger holes if there are any. This would leave an area where the sealing material can accumulate and not be compleatly squeesed out. Of course I did not come up with this on my own I had seen this done when bedding deck hardare. For counter sinking holes I perfer to use a new (or never used for concreat) 1" masenary bit rather then a counter sink. Its carbide tipped so it cuts well and preduces a flatter 118 deg counter sink then a standard 82 or 90 degree counter sink.

Pete

[okawbow]

I used 3M 4200 on my mast step. It appeared to have a similar material originally. I use butyl for most other deck hardware, but I think the mast step benefits from an adhesive sealant.

[Hirilondë]

I do not use butyl at all. If I did, the only application would be ports. This might change for ports though, I am beginning to like the idea of butyl in this application. Because it never cures it will always be prone to being squashed out when forces act upon the item bedded with it. There really are no such forces on ports. There are on deck hardware and such. There certainly is on a mast step. I do not see any real need for a strong adhesive sealant on a mast step as the loads on it are mostly compression, not lateral. A moderately adhesive sealant might be called for, though one could argue that no adhesive property is needed at all.

Anyway, enough distraction form the original question. I would choose a polysulfide or a moderately adhesive polyurethane depending on which I had an open tube of.