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wstigg 09-13-2008 06:44 PM

Sealing the inside of mast
 
Hi - My keel-stepped 67' aluminum mast has many halyard openings that invite rainwater and spray into the mast. This drains harmlessly into an otherwise dry bilge. Does anyone have experience with expanding foam or other solutions that would keep the water above deck level? I've thought of inserting a balloon into the mast at deck level and inflating it, thereby creating a plug to keep the foam from running down the mast. Will the foam create a good seal around the wires? Many thanks for your thoughts! Willy

knothead 09-13-2008 07:07 PM

Quote:

Originally Posted by wstigg (Post 368213)
Hi - My keel-stepped 67' aluminum mast has many halyard openings that invite rainwater and spray into the mast. This drains harmlessly into an otherwise dry bilge. Does anyone have experience with expanding foam or other solutions that would keep the water above deck level? I've thought of inserting a balloon into the mast at deck level and inflating it, thereby creating a plug to keep the foam from running down the mast. Will the foam create a good seal around the wires? Many thanks for your thoughts! Willy


Willy, Selden has a procedure for making a dam in their spars.

I had to get a radar cable through one of them once. What a pain.

At the moment, I am not capable of having a coherent conversation on the subject because I am half way through a Rays double header with the Yankees and am feeling no pain. But I can see if I can dig up further information on monday if you like.

sailingdog 09-13-2008 07:16 PM

If you do create a dam in the mast, you will want to leave a drainage hole just above it, so that water doesn't collect inside the spar.

hellosailor 09-13-2008 07:19 PM

Willy, if you build a damn in the mast, you'll still need to place a drain hole above it. And then worry that unless the dam is concave shaped on top--something like a balloon would invite water to pool around the top of the damn and corrode from the inside.

A small dam in the bilge and a small bilge pump, with small diamter hose, to keep the seepage out should do the trick without going into the mast or embedding the wiring in it.

wstigg 09-14-2008 04:46 PM

Hello Knothead Steve -
 
Many thanks for your prompt reply. My mast is, indeed, Selden. I visited their website but couldn't find any reference to damming the inside of the mast. If you can point me toward info on this I'd be much appreciative. Thx! Willy.

knothead 09-14-2008 04:50 PM

Quote:

Originally Posted by wstigg (Post 368559)
Many thanks for your prompt reply. My mast is, indeed, Selden. I visited their website but couldn't find any reference to damming the inside of the mast. If you can point me toward info on this I'd be much appreciative. Thx! Willy.

I'll get back to you tomorrow when I am at the shop.
They do indeed have a drain hole above the dam, but I can't for the life of me remember how they make the dam.
I can almost assure you that they do it with the mast horizontal though. :(

knothead 09-15-2008 10:49 AM

Willy, Essentially what they do is create a sandwich of sorts in the mast where they want the dam using pieces of foam that are fitted perfectly to the inside of the spar. They drill the drain holes and insert clevis pins which will be removed later. The top foam piece of the sandwich is pushed up to the drain hole clevis pins. They drill a couple of fill holes and using a Sikaflex type of material, fill the area between the foam pieces thereby creating a dam.

I really can't see any way of accomplishing this with the mast stepped.
But if you decide to pull the stick you could probably make it work then.

You mentioned that your mast is a Selden. If you look at the base of the mast and copy down the engraved number/letters there, you could contact Selden and they can pretty much tell you everything about it.

Frankly, I am somewhat surprised that it doesn't have a dam in it already.

Please don't make the mistake of squirting that expandable foam stuff in though. You or someone along the line will surely regret it.
Better to live with a little water in your bilge.

If you see corrosion developing around the base of the mast or step, spray it with some kind of corrosion block or something.

Good luck.

Maine Sail 09-15-2008 11:00 AM

Consider..
 
Consider creating a mast base bilge sump. We have one on our boat and it is one of the best features. All the rain and fog moisture gets trapped in the bilge sump and I suck it dry with a turkey baster after a big rain..

Expandable foam six feet up a mast will be a ROYAL PITA in the future if you need to do any sort of repairs or re-wiring. Sealing around the wires will also be very difficult to do at at even a 80% success rate let alone 100% dry..

Again, the mast sump keeps the rest of our bilge at dusty dry levels along with the PSS and dry non leaking deck fittings and no domestic plumbing leaks...

I remember reading a while ago on one of the forums of a guy who bought a boat where the PO had injected expanding foam and of his resulting cuss words and headaches associated with trying to run a new radome wire. Oh and if I remember correctly his mast still leaked into his bilge.

wstigg 09-23-2008 01:47 AM

To knothead Steve -
 
Hi Steve - Heaps o thanks for getting back to me re: sealing the inside of my Selden spar. The mast came with a fitted foam chunk about deck level but I had to remove it to install an inside headstay fitting that needed to go up the inside of the mast. This block may have been dam. Nuts. Next time I pull the rig, I'll follow your proceedure. Until then, I'll seal the very foot of the mast from the outside and drill a small drain hole and hose to drain down into a catch bucket. This should do just fine. Many thanks again
!


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