Mounting Stanchions

[coopec43]

I would be very interested to get the opinion of people who have "been there, done that" on how I should mount the stanchions on deck.

I am reluctant to mount the base of the stanchion directly on to the deck as I know it will mean I have deck leaks (even if I use butyl tape) I have therefore made up polyester fiberglass "mounts" to raise the base of the stanchion slightly above the deck.

I thought I'd sand the deck where the stanchion is to be mounted and then use polyester bog to "glue" the mount to the deck. Then I'd mount the stanchion using butyl tape. Has anyone got a better idea?

I have taken a photo with my camera, emailed the photo to my desktop and then cropped it (first time I've done that!) (The mount is tapered on this stanchion to make up for the curve of the deck)

[pcmm]

I think you are attempting to far over think this. Yes stanchions can leak, in fact any fitting with deck penetrations can leak. There are well documented techniques for getting around this problem. Over drilling, filling and redrilling takes care of the core issue. Adding a small countersink to the hole for the butyl to seat into gives the butyl a place to form a gasket. Proper installation technique ( not really hard) with butyl solves that problem. My stanchions bases were assembled 40+ years ago and still do not leak.

If they are leaking its an install issue not a flaw.

I don't think bedding a riser of glass in polyester "bog" is a good idea, If you choose to go that route, epoxy is much stronger as a secondary bond than polyester.

[Manateeman]

Make some pads about 1/2” high. G10, fiberglass, whatever. Bevel the edges for your feet. Epoxy them to the deck. Drill, clean, scuff up the bottom of the stainless with 36 on a mini grinder, acetone, stick on with 5200 not hard then retighted in a few days.
Never liked tape.
The manatee crew

[coopec43]

Originally Posted by pcmm

I think you are attempting to far over think this. Yes stanchions can leak, in fact any fitting with deck penetrations can leak. There are well documented techniques for getting around this problem. Over drilling, filling and redrilling takes care of the core issue. Adding a small countersink to the hole for the butyl to seat into gives the butyl a place to form a gasket. Proper installation technique ( not really hard) with butyl solves that problem. My stanchions bases were assembled 40+ years ago and still do not leak.

If they are leaking its an install issue not a flaw.

I don't think bedding a riser of glass in polyester "bog" is a good idea, If you choose to go that route, epoxy is much stronger as a secondary bond than polyester.

There's an enormous amount of strain on stanchions so I don't mind overthinking. But a recent article I read by an expert on boat construction stated 95% of leaks will be stopped if the mountings are "proud" of the deck.

I'm not too worried about epoxy being stronger than polyester as the mount will be bolted anyway.

[pcmm]

Originally Posted by coopec43

There's an enormous amount of strain on stanchions so I don't mind overthinking. But a recent article I read by an expert on boat construction stated 95% of leaks will be stopped if the mountings are "proud" of the deck.


I'm not too worried about epoxy being stronger than polyester as the mount will be bolted anyway.

Maybe I've been lucky as my previous fiberglass boats (excepting the current one) had specific mounting spots for the stanchions in the form of a slightly raised areas moulded in to the decks. which was convenient, but a pain if you can't find a correctly fitting replacement when one breaks!

If you are just using the pad to raise the stanchion, go for it. I was under the impression from the original post that you were trying to avoid leaks..i.e. holes through the deck.

Risers are a great idea just as Manateeman said, radius the top edge a bit to prevent a bit of toe bashing!

[Rumrace]

I’d pick a poly base over wood even nylon.
I have some PC nylon which is amazing.
Wood will draw water to area. You can use a Wood sealer from minwax which fill open cells with Epoxy. Renders the wood rock hard. I drill through bolt holes twice one oversized the next one I tap through Epoxy. That way they is no chance a stress crack will start water migration.

[coopec43]

Originally Posted by Manateeman

Make some pads about 1/2” high. G10, fiberglass, whatever. Bevel the edges for your feet. Epoxy them to the deck. Drill, clean, scuff up the bottom of the stainless with 36 on a mini grinder, acetone, stick on with 5200 not hard then retighted in a few days.
Never liked tape.
The manatee crew

Yes, I agree with your approach.

Stanchions will move because people use them to haul themselves aboard, steady themselves in bad seas etc.

My opinion of butyl tape is that it is excellent where the fittings will not move - windows, deck hatches, dorade boxes etc. I don't think it is the best product for stanchions. (Maybe 5200 is the way to go?)

[rslifkin]

It's definitely not a bad idea to build the deck up slightly where the stanchions mount. It'll reduce the amount of water that can flow over the fasteners, reducing the chance of a leak. Although if they're mounted well, they're unlikely to leak as others have said. Appropriate backing plates and adequate surface area for the stanchion bases goes a long way to keeping stuff from flexing. If it doesn't move or flex noticeably, it's much easier to keep things sealed properly.


As far as sealant, butyl stays soft, but may squish out of the joint over time. 4200 / 4000UV / 5200 (or other similar adhesive sealant) should avoid that problem and work fine. In any case, go with the countersunk bolt holes in the deck, as that'll let a ring of sealant get down in there making it less likely to ever leak (even if a little bit of movement compromises the layer of sealant between the deck and stanchion base).

[Spot]

Coop, I like your picture. Sort of a 1940's movie vibe where they do a close-up on an aging starlet and it goes all soft focus...I should use that technique more on my own boat

Is your deck cored? There was a thread a while back where I tried to capture the ideas via pictures.

I like your pads. I don't think I'd go 5200, maybe something a hair easier to remove if needed.

[Bowdrie]

Pads that raise fittings off of the deck are always a good idea.
Besides greatly decreasing the chances of water ingress they serve as a "backing" plate to spread the compressive load of the fasteners over the top of the deck, just like the underside ones do.
Cleats and padeyes, (with their tiny mounting surface area,) should always be on raised pads, and it sure makes cleaning/painting around them much easier, ease of use is also enhanced.
Ditto on windlasses, and their deck mounted switches.
Stanchion pads also provide the opportunity of incorporating changing bevels so that the stanchions don't "stick out" at all kinds of funny angles, thereby adding some symmetry and grace to the visual.

[s/v Jedi]

You’re doing great!

For mounting it is important to check the mounting holes through the deck. The deck should be solid glass, i.e. they stopped the core before getting closer to the cap rails. If you find core material, then you need to overdrill to something like 3/4” diameter through the upper skin and the core but not the inside skin. Fill this with epoxy thickened with high density filler (sold by West System and others) so that it is ketchup consistency that still freely flows. Poke it with a toothpick to release as much air bubbles as possible.

A hole saw works good for this. Re-drilling can be a challenge to get aligned and into the original holes below. I often do half the holes in a first pass, where you can use the other holes as guides to keep the part in place while re-drilling.

When you don’t have the butyl tape from Rod Collins then I recommend to use either 5200 or LifeCaulk. LifeCaulk is a polysulfide like 3M 101 was, which was the go-to sealant for this application.
I tried other butyl tape but it all failed, especially the one from West Marine.

[coopec43]

Originally Posted by Spot

Coop, I like your picture. Sort of a 1940's movie vibe where they do a close-up on an aging starlet and it goes all soft focus...I should use that technique more on my own boat

Is your deck cored? There was a thread a while back where I tried to capture the ideas via pictures.

I like your pads. I don't think I'd go 5200, maybe something a hair easier to remove if needed.

Hi Spot. Yes the deck is cored (Divinycell). I'll take your advice and check out the different adhesives/sealants. Thanks.

[coopec43]

Originally Posted by s/v Jedi

You’re doing great!

For mounting it is important to check the mounting holes through the deck. The deck should be solid glass, i.e. they stopped the core before getting closer to the cap rails. If you find core material, then you need to overdrill to something like 3/4” diameter through the upper skin and the core but not the inside skin. Fill this with epoxy thickened with high density filler (sold by West System and others) so that it is ketchup consistency that still freely flows. Poke it with a toothpick to release as much air bubbles as possible.

A hole saw works good for this. Re-drilling can be a challenge to get aligned and into the original holes below. I often do half the holes in a first pass, where you can use the other holes as guides to keep the part in place while re-drilling.

When you don’t have the butyl tape from Rod Collins then I recommend to use either 5200 or LifeCaulk. LifeCaulk is a polysulfide like 3M 101 was, which was the go-to sealant for this application.
I tried other butyl tape but it all failed, especially the one from West Marine.

The deck of the yacht is cored but there is a marine ply "inserts" where-ever there is a deck fitting - winches, stanchions cleats etc. It wouldn't be hard to overdrill the "marine ply insert" and fill with thickened epoxy.

Good idea!

[s/v Jedi]

Originally Posted by coopec43

The deck of the yacht is cored but there is a marine ply "inserts" where-ever there is a deck fitting - winches, stanchions cleats etc. It wouldn't be hard to overdrill the "marine ply insert" and fill with thickened epoxy.

Good idea!

Yes, with marine ply I would do the epoxy plugs as well. It completely prevents any problems with it getting wet

[whmiles]

I know this thread is a bit old, but I have a particular problem with installing my new stanchions. I have had to do an extensive repair on the deck/topsides of my Roberts34 (Foam GRP sandwich).
Over decades it seems that water ingress through deck stanchion mountings had rotted out a large area of (can you believe it) 4” thick vertical grain Oregon in the topsides down about 18 inches. I had to attack it from inside the boat first after the deck had been opened, creating a gaping hole. It is now repaired leaving me wondering how to mount the stanchions.
If I move these stanchions inboard to avoid the thick topsides (containing that wood) they are halfway across the available deck. Not an option. I cannot through bolt the bases.
I am left with the proposition that the bases must be mounted entirely on the deck surface. No through bolts. A good boatbuilder told me this is quite possible, but I no longer have contact with him. Does anybody have experience with the specs and techniques required to ensure adequate impact strength for full installation of on-deck stanchions?