Refitting deck hardware - sealing?

[Jaco Versfeld]

Good day,


My apologies if this is the wrong sub-forum.


We recently picked up that the attachment for the front stay was failing - luckily we saw this in time!


We had to remove the pull-pit, as well as the "nose-cone" in order to fix. We have welded a new attachment, and all seems to be good now.


However, we want to seal the through deck holes for two of the stanchion bases, as well as the "nose cone".


The workshop manager that assists me recommends we use a bitumen based product. Will the following work as a layer between the deck and the bases, for the nose cone as well as the two stanchion bases:


https://www.builders.co.za/Paint-%26...00000000660876



(Edit: the one side has an "aluminum foil" and the other side is a thin (0.5 mm??) bitumen layer )







Kind regards,
Jaco

[Jaco Versfeld]

I think this might be the equivalent product in the USA:


https://www.amazon.com/BXI-Flashing-...2556483&sr=8-9

[BillKny]

I am not at all sure how you go about using this kind of product, but I'd be very reluctant to put aluminum in a sandwich with stainless steel.

I'd use butyl tape for this application.

[Sailmonkey]

If that’s all that’s available, it’ll work. But there are a lot of better products.

Butyl tape
Polyurethane
Polysulphide

[Winter River]

This is the best butyl tape: Bed-It Tape

All you ever need to know about bedding hardware: marinehowto.com

[joelhemington]

Originally Posted by Winter River

This is the best butyl tape: Bed-It Tape

All you ever need to know about bedding hardware: marinehowto.com

Thanks for that link - great source which I've bookmarked in my sailing file

[Jaco Versfeld]

Thank you,


Very useful info!


Thanks,
Jaco

[Markb250]

Yeah, I just read the marinehowto link from Winter River. I'm a devotee of the two step method. I accept the concerns for this method outlined in that article, however, I feel that in the case of a pulpit stanchion base, it is the best option. The reason I say this is that the rigidity of the pulpit frame will prevent those stanchion bases from perfectly aligning face to face with the deck, as would be the case with an individual deck fitting free to align with the deck.

The two step method will provide sufficient sealant thickness to accommodate any potential variable spacing between the base plate and the deck.

Place the bolts in the base plate and seal the underside, introduce to the deck holes and place a 5mm packer(s) just nipped into the plate from the outside and lightly tighten the nuts, mask out the deck and plate and apply the (polyurethane) sealant and tool smooth (finger?). Remove the spacer and tighten when cured. Remember that sealant works best as a bead adhering to 2 surfaces, not 3.

[bcboomer]

Originally Posted by Markb250

Yeah, I just read the marinehowto link from Winter River. I'm a devotee of the two step method. I accept the concerns for this method outlined in that article, however, I feel that in the case of a pulpit stanchion base, it is the best option. The reason I say this is that the rigidity of the pulpit frame will prevent those stanchion bases from perfectly aligning face to face with the deck, as would be the case with an individual deck fitting free to align with the deck.

The two step method will provide sufficient sealant thickness to accommodate any potential variable spacing between the base plate and the deck.

Place the bolts in the base plate and seal the underside, introduce to the deck holes and place a 5mm packer(s) just nipped into the plate from the outside and lightly tighten the nuts, mask out the deck and plate and apply the (polyurethane) sealant and tool smooth (finger?). Remove the spacer and tighten when cured. Remember that sealant works best as a bead adhering to 2 surfaces, not 3.

The auto industry went away from the "2-step" process about 30 years ago.
When you tighten the fittings after the sealant has cured the squishing of the sealant tends to make it separate from the fitting.
That, plus the inevitable flexing and temperature driven stress, will result in premature leaks.

[ussvdharma]

I have been told and have always followed the following:
- tighten down the fitting till it contacts the sealant. then 1/2 turn more.\

- Once the sealant has set and is almost completely dry, then and only then
finish the tightening of the fitting.


If a fitting is tightened down into the sealant completely when it is still wet, you do not get complete sealing that will last.


good luck, de W7KFI ussvdharma (Susan)

[Puget Dan]

Originally Posted by Winter River

This is the best butyl tape: Bed-It Tape

All you ever need to know about bedding hardware: marinehowto.com

Thanks, the marine how to site if great.

[sazarac]

I use a cork gasket between two layers of butyl.

[geoff3nebel]

Sikaflex 921i

[GordMay]

When tooling polyurethane adhesive/sealant (5200 etc), I always found wetting (finger or tool) with a very slightly soapy* water to greatly improve the finished finish, and cleanup.

* I used very little dish washing liquid (in warm water) - just enough to feel slippery.

[Joli]

If the fitting is through bolted and you can turn the nuts from below them butyl tape works very well. If the fitting is screwed into the deck then polysulfide or 4200 work best.