Anyone know how to install deck hardware that doesn't leak?

C

carl170

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halcyon23.blogspot.co.uk
Hi (again)

I was wondering if anyone knew the correct way to install and seal deck fitting?

I have a few books by dan casey and he always suggests to clean surfaces, use silicone sealant, clamp it down a bit and leave it to set (to form a gasket). This can then be nipped up another turn and then the excess is trimmed with a razor blade.

This has never worked for me! I can never trim the excess rubber off without breaking some off, or scratching the deck. It is diifcult to know how thick the gasket is supposed to be too.

I recently saw another post:

http://www.pbase.com/mainecruising/rebedding_hardware

which takes quite a different approach.

Has anyone tried either, or can suggest a way that definitely works?

Thanks as always,

Regards

Carl
 
Last edited:
The proceedure in your link works. However there are otherways. I think that the biggest mistake is that were a bolt goes through the deck you should avoid turning the head and only tighten up the nut so that the sealant isn't twisted round as you clamp down the fitting. The right sealant also helps and I have had best results with Sealastic (a liquid butyl sealant I believe) and with buytl tape (excellent on windows). The only other sealant that seems to have given reasonable service is Geocel.

I would tend to agree that if you can leave a fitting for 24 hours before giving it a final 1/4 turn then it is probably worth it.

Yoda
 
Davegriff said:
+1
Click to expand...
+2 Non setting sealants, and the use of Boat cotton on bolts, plus sealant, and penny washers or plates to spread the load, always worked well for me..
I once had to remove the engine hatch from a Nelson 42 that had been sealed with Sikaflex. It did nt leak, but it didnt come out... Don t ever use that on something you may wish to remove later...
 
sailorman said:
I dont get leaks & have never used silicone either.
i generally use a polysulphide mastic & make sure its around the thread of the fixing. bolt up & clean off with white spirit, job done.
Click to expand...

Yup. Arbokol 1000 is hard to beat. Slap it on, slap down the fitting, tighten it up and if it squeezes out all the way around then it will not leak.

Silicone isn't really suitable for outdoor use.
 
No-one mentioned Sikaflex yet? I've fitted loads of deck fittings using Sikaflex as a bond/sealer. Never leaked. Use meths to clean off excess.
 
IMHO the secret is to seal the holes around the bolts.

Not necessary generally to seal or bond the fitting itself to the deck provided the bolts/screws are sealed in their holes....... In fact this is vital to prevent crevice corrosion when the fastenings are stainless steel.

A bead of sealant round the bolt in the way that butyl cones are shown in this picture from Carl's link will do the trick..... even if it's silicone.

123303887.OAYEIwwS.jpg
 
VicS said:
IMHO the secret is to seal the holes around the bolts.

Not necessary generally to seal or bond the fitting itself to the deck provided the bolts/screws are sealed in their holes....... In fact this is vital to prevent crevice corrosion when the fastenings are stainless steel.

A bead of sealant round the bolt in the way that butyl cones are shown in this picture from Carl's link will do the trick..... even if it's silicone.

123303887.OAYEIwwS.jpg
Click to expand...
Fine for grp, but if your fixing down to any sort of timber you want to seal around the whole fitting since water trapped underneath will start rot in no time. Personally when sealing things down I go round both the bolt holes and the fastening.
 
Woodlouse said:
Fine for grp, but if your fixing down to any sort of timber you want to seal around the whole fitting since water trapped underneath will start rot in no time. Personally when sealing things down I go round both the bolt holes and the fastening.
Click to expand...
Even on GRP which is seldom as flat as the machined base of a fitting you don't want water sitting under the base, it will corrode. I always use either butyl mastic tape or neoprene tape. It's far cleaner to use than trying to pipe mastic out of a gun.
 
sailorman said:
I dont get leaks & have never used silicone either.
i generally use a polysulphide mastic & make sure its around the thread of the fixing. bolt up & clean off with white spirit, job done.
Click to expand...

I agree - the white spirit doesn't really dissolve the polysulphde but acts as a lubricant to your wiping to ensure that you end up with a clean edge. Its quick and efficient and its how a boat builder taught me to do it when I was struggling trying to wok out how to end up with a 'clean' edge of sealant round fittings.

yoda said:
The proceedure in your link works. However there are otherways. I think that the biggest mistake is that were a bolt goes through the deck you should avoid turning the head and only tighten up the nut so that the sealant isn't twisted round as you clamp down the fitting. The right sealant also helps and I have had best results with Sealastic (a liquid butyl sealant I believe) and with buytl tape (excellent on windows). The only other sealant that seems to have given reasonable service is Geocel.

I would tend to agree that if you can leave a fitting for 24 hours before giving it a final 1/4 turn then it is probably worth it.

Yoda
Click to expand...

This was exactly my thought. It takes a bit of skill and thought, but you need to ensure that the bolt/fastening through the 'cured' sealant doesn't rotate when you finally 'nip it up'

Lakesailor said:
No-one mentioned Sikaflex yet? I've fitted loads of deck fittings using Sikaflex as a bond/sealer. Never leaked. Use meths to clean off excess.
Click to expand...

I agree. I've bedded lots of things using Sikaflex and never had these problems in removing them that other people seem to have when I've needed to take the things off. The only one that ever leaked was a chain plate I bedded ten years ago and didn't use the 'wait for it to cure and nip it up the next day' technique. I'd squeezed all the sealant out and got a drip through from time to time. I did the job again (properly) when at anchor in the Golf du Morbihan. Allowed it to cure overnight and nipped it up and it hasn't leaked since. I don't like silicon sealants and haven't found them as effective as Sikaflex. They 'peel' off some surfaces, but Sikaflex seems to stick to anything! I note that cheaper polysulphides are available.


I'm quite prepared to give the butyl tape a go, but I am VERY concerned that the link in the OPs post doesn't mention the dangers of crushing sandwich construction decks. Whether its balsa or foam, I strongly suggest that one needs to fiddle about with a bent nail/small screwdriver etc to remove a section of the balsa or foam around the hole and then cast a plug of solid thickened epoxy through which you re-drill the hole to mound the fitting. The sold plug of epoxy then stops you crushing the deck as you tighten the fitting down. I use an old allen key in a drill with a vacuum cleaner nozzle near the hole to shred the balsa in the sandwich of our deck when I want to mount a new fitting. Again, I haven't had one of those leak yet. They are also appreciably more 'solid' than some of the earlier ones that previous owners had fitted and which I am working round re-fitting.
 
I have found that a countersink on the deck hole and if practical on the underside of the hardware when used with decent sealant works well as it prevents the sealant being squeezed away from tat vital area, combined with a bit of thinner liquid sealant under the outside bolt heads and I get no leaks even on underwater stuff like transom mount transducers and the like.
 
VicS said:
IMHO the secret is to seal the holes around the bolts.

Not necessary generally to seal or bond the fitting itself to the deck provided the bolts/screws are sealed in their holes....... In fact this is vital to prevent crevice corrosion when the fastenings are stainless steel.

A bead of sealant round the bolt in the way that butyl cones are shown in this picture from Carl's link will do the trick..... even if it's silicone.

123303887.OAYEIwwS.jpg
Click to expand...
Best to completely seal under flanges to prevent corrosion
 
David2452 said:
I have found that a countersink on the deck hole and if practical on the underside of the hardware when used with decent sealant works well as it prevents the sealant being squeezed away from tat vital area, combined with a bit of thinner liquid sealant under the outside bolt heads and I get no leaks even on underwater stuff like transom mount transducers and the like.
Click to expand...

That is the key IMHO.
It means the sealant is not stressed by the fitting, and there is a decent thickness of sealant to move.
You can stretch silicone at least 50% without it failing, so if you have a 1mm countersink it is in with a chance, but if it is squeezed to zero, small movement will break the bond.
Mounting fittings on rafts of sealant then tightening when it has cured will not always work. It means the fitting will always move under load. OK if loads are small.
 
lw395 said:
That is the key IMHO.
It means the sealant is not stressed by the fitting, and there is a decent thickness of sealant to move.
You can stretch silicone at least 50% without it failing, so if you have a 1mm countersink it is in with a chance, but if it is squeezed to zero, small movement will break the bond.
Mounting fittings on rafts of sealant then tightening when it has cured will not always work. It means the fitting will always move under load. OK if loads are small.
Click to expand...


I think I will get some Arkobol 1000 or something similar. Are all polysulphide sealants pretty much the same?

Also, where is a a good place to get them - obviously not our local chandlery!

I think I will try the countersink trick - is there a certain depth that is best? I am consious that very mm I drill out will be weakening the deck!

Do you nip it right down to leave a 1mm raft or do you just tighten it right down?

Cheers

Carl
 
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