How to make a watertight glass deck?

[250224]

In a post [1] discussing aluminium cats it has been written:

"It is easier to make aluminum decks totally watertight, but the good glass guys have now learned how to do exactly the same."

What does this mean? E.g. my stanchions are fixed with screws that go through the deck and with time the Sika bedding starts to leak. Would like to fix such things for good...

[1] https://www.cruisersforum.com/forums...ml#post3068364

[Chotu]

Originally Posted by blu3534

In a post [1] discussing aluminium cats it has been written:

"It is easier to make aluminum decks totally watertight, but the good glass guys have now learned how to do exactly the same."

What does this mean? E.g. my stanchions are fixed with screws that go through the deck and with time the Sika bedding starts to leak. Would like to fix such things for good...

[1] https://www.cruisersforum.com/forums...ml#post3068364

One solution is composite Stanchions epoxied right through the deck and attached to the bulkheads.

[slug]

Originally Posted by Chotu

One solution is composite Stanchions epoxied right through the deck and attached to the bulkheads.

Integral station bases are a nightmare
A simple docking goof up or a mistaken sheet leed and you’ve got a 10 grand repair

Do go there

And don’t go composite stations

https://websites.sportstg.com/get_file.cgi?id=2767243

When they fail they splinter

I’ve seen properly installed ,watertight, 30 year old stainless stations

[250224]

Originally Posted by slug

I’ve seen properly installed ,watertight, 30 year old stainless stations

Can you expand a bit what you mean with "properly installed". Thanks.

Btw, the question is not only about stanchions. There is also the attachment of the inner forestay (Kutterstag) which currently goes through a hole and is fixed on the bulkhead. Or the genoa tracks where some screws also (minimally) leak.

I can only think about using plenty of Sika. But this wouldn't be the same as with an alu/steel deck where one can weld and no holes are there.

[GRIT]

We used Stainless tubing, sized to fit inside the stantion.

We had a collar welded to the tubing, about 15cm from the top, to act as a base for the stantion. The tubing extends 20cm down from there, and was epoxied into the deck, with the collar flush with the deck. We then made glass gussets around the 18cm base of the tube, to fasten it to the hull sides and deck bottom. They're pretty rugged, and water tight.

Cheers.
Paul.

[Breaking Waves]

For stanchions:
G10 rod, glassed thru deck, and under deck glassed to hull (or bulkhead/knee). Above deck, stanchion slid over rod, with set screw. Is watertight and strong, and still makes stanchion removable/repairable.

For chainplates:
Carbon uni fibers run over stainless tube, down thru deck, and around bulkhead/hull/knee. Bolt thru stainless tube holds stay toggle bottom. This is very common on race boats, you can google picture, will become perfectly clear.

For attachment of the inner forestay:
Can do as above, or run G10 flat bar, glassed thru deck down to hull and glassed there. Just simple hole in flat bar above deck for stay attachment.

For genoa tracks:
If you have cored decks, take G10 flat bar length of track, tap appropriate machine screws holes in it to match track, route slot in deck size of flat bar down thru core to top of inner skin, glue flat bar in slot. Is best to also replace some core either side of slot with thickened epoxy (and/or glass from top of flatbar to top skin) but usually not absolutely necessary - but nice to ease stress riser either side of bar. On uncored decks you can just glue the flat bar right on surface.

There are other techniques, some better for particular situations, but that gives you an idea.

[250224]

Originally Posted by Breaking Waves

There are other techniques, some better for particular situations, but that gives you an idea.

Great, thank you very much! (Also to the other replies!)

[doog]

Yes a properly bedded fitting involves over drilling the hole and filling with epoxy or sealant to prevent any seepage into the wood or structure, then bedding the stanchion base or toe rail or fittings into a well sealed hole which even if it leaks at the surface will not seep into the structure. Seems only a few mechanics do this even with the tiny canvas fastener screws and the penetrations become rot spots all too soon. Ive seen beautifully built cold molded wood boats with stanchion bases leaking into the wood fiber and showing expansion damage all along the topsides..a 200K boat turned into a repair project of huge proportions! Far beyond what is covered by the value of the boat..

[skipmac]

Originally Posted by blu3534

Can you expand a bit what you mean with "properly installed". Thanks.

Btw, the question is not only about stanchions. There is also the attachment of the inner forestay (Kutterstag) which currently goes through a hole and is fixed on the bulkhead. Or the genoa tracks where some screws also (minimally) leak.

I can only think about using plenty of Sika. But this wouldn't be the same as with an alu/steel deck where one can weld and no holes are there.

You can get more detail with pictures from the Compass Marine web site (forum member Maine Sail) but here the short version.

Any holes in the deck drill to a larger size, fill with thickened epoxy then redrill the original size hole. Reinstall the stanchion or fitting.

Any deck hardware bed with butyl tape. Stays sealed and flexible for as long as anyone I know has tested it. You can buy the proper marine grade from Compass Marine here. https://shop.marinehowto.com/products/bed-it-tape

[skipmac]

Here's the link to the how to. I've done all my boats this way and once done properly no more leaks.

https://marinehowto.com/bed-it-tape/

[Daniel Grant]

All of my stanchions are on raised pads which prevents any water running down the deck from getting around the bottom of the Stanchions. When I replaced my chain plates I poured pads around the slit in the deck to prevent water running down the deck from getting in the slot. Many of my friends have used butyl rubber tape under the stanchions and have never reported a problem. I know this does not answer the original question but it helps.

[250224]

Originally Posted by Daniel Grant

When I replaced my chain plates I poured pads around the slit in the deck to prevent water running down the deck from getting in the slot.

I don't understand, "poured pads around the slits", does this mean some kind of elevated podium where you put the chain plate on top? If yes, how does this help when e.g. the water temporarily "floods the deck" 3 cm high?

Many of my friends have used butyl rubber tape under the stanchions and have never reported a problem. I know this does not answer the original question but it helps.

Still good to know, thank you, just collecting options atm. --

I liked the tip "G10 rod, glassed thru deck, and under deck glassed to hull ... Above deck, stanchion slid over rod, with set screw" a lot (no holes whatsoever!), but 1) it seems quite complicated work and 2) I'm currently asking myself what would happen if too much force will be applied to the stanchion. Would the stanchion-G10-combination rip out part of the deck... ? The ss base plates seem to be "sacrificial" and would break. But I (currently) don't know the strength of G10.

[Daniel Grant]

The poured epoxy raised area (about 1 1/2 to 2 inches high)has a somewhat pointed area toward the bow which deflects water to each side. I also over cut the width and length of the slot, undercut the deck around the slot and poured the slot with thickened epoxy. I then cut a new slot. When the chain plates were replaced they were bedded as usual but bedded the entire depth. It has been 7 years and not a drop has passed through. It took some time but worked well for me.

[250224]

Originally Posted by Breaking Waves

For genoa tracks:
If you have cored decks, take G10 flat bar length of track, tap appropriate machine screws holes in it to match track, route slot in deck size of flat bar down thru core to top of inner skin, glue flat bar in slot. Is best to also replace some core either side of slot with thickened epoxy (and/or glass from top of flatbar to top skin) but usually not absolutely necessary - but nice to ease stress riser either side of bar. On uncored decks you can just glue the flat bar right on surface

On uncored decks I understand this to be:

   __x__x__x__x             # track with screw holes (x)
   ==x==x==x==x==           # G10 flat bar with holes (x), glued to deck
--/||||||||||||||\--        # deck with glue (|) for flat bar

But unfortunately I don't understand what you mean for cored decks (which I have). "route slot in deck size.. down thru core"? "glue flat bar in slot"?

Btw, any "gluing" would be with epoxy?

[Breaking Waves]

Originally Posted by blu3534

I liked the tip "G10 rod, glassed thru deck, and under deck glassed to hull ... Above deck, stanchion slid over rod, with set screw" a lot (no holes whatsoever!), but 1) it seems quite complicated work

it is not complicated on a new build, but yes it is typically some work on an existing boat - rather more than drilling 4 holes and using stainless bolts. But it is the best way to do the job.

and 2) I'm currently asking myself what would happen if too much force will be applied to the stanchion. Would the stanchion-G10-combination rip out part of the deck... ? The ss base plates seem to be "sacrificial" and would break. But I (currently) don't know the strength of G10.

The typical hollow stainless stanchion will bend/crimp well before the G10 rod stub will break. I have seen tests first hand. You can very very easily do your own - get a short piece of g1o rod (size = snug fit inside stainless stanchion - put it in vice (with plastic jaws), put stanchion over it, lever the **** out of it - it will 100% be the stainless stanchion which gives first.

But unfortunately I don't understand what you mean for cored decks (which I have). "route slot in deck size.. down thru core"? "glue flat bar in slot"?

Btw, any "gluing" would be with epoxy?

There are various glues (including plexus) which can work, but epoxy is common and does the job.

With a cored deck, if you simply glue it on top there is a small possibility you pull the top skin up off the core - it should not happen if the laminate was properly made with proper core bond but some cores (especially honeycomb) can have a weak bond. One way to get around this is to glue the g10 flat bar under the decks so it pulls up, and that will be structurally sound, but often on an existing boat there is ceiling and interior in the way. So . . . . .

lets say you have 2" wide x 6' long flat bar. In your decks you take router, with cut dept set to top skin plus core thickness (so it cuts right down to top of inner skin) and route out 2" wide x 6' long section in deck. You glue the flat bar in that 'slot/hole'. Typically the flat bar thickness is selected to it ends up flush with the top of the deck.

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