Seacock Sealant

[JakeMM]

Hi,

I recently removed a seized seacock (Blake's) and have now freed it up ready to be put back on the boat.

I'm stuck as to which type of sealant/adhesive I should use?

Looking briefly, I came across Sikaflex 291 and Aquaseal 295.

Any thoughts as to whether either of these would be suitable? (I have yet to find a sealant that specifically states it's for Seacocks).

I've also got a loose depth transducer which I would like to seal to the inside of the hull and I'm hoping the same sealant/adhesive can also do this job.

Thanks Jake

 

[alahol2]

Save some money and use PU40 (or equivalent from other DIY sheds)... http://www.toolstation.com/shop/Adhesives+%26+Sealants/d180/General+Sealants/sd2350/Polyurethane+PU40+Sealant+300ml/p67949
Specifically look for ones that can be used on damp surfaces.
As to the 'loose depth transducer', why is it loose? NASA for example specify that, having screwed down onto sealant, the tube should be more permanently fixed with a fillet of GRP/Epoxy paste/filler.

 

[MagicalArmchair]

Recently asked the same question of Sika, had this in response:

Hello Mark,

Many thanks for the below enquiry.
For the below application we can suggest for you to use Sikaflex 295uv however Sika Aktivator 205 must be used prior.
I have attached the Data Sheets for both products for your reference.

Kind regards

James

 

[jakeroyd]

As far as I am aware Sika 295 is for applications requiring high UV resistance (hence the suffix) mainly windows etc in the superstructure. You do not need this for a seacocks.
i used 291 to replace a seacocks skin fitting and the cock and the fittings as well.
it has been completely successful.
to time the fittings so the waste hose could be connected I could not fully tighten the elbow.
after a day or so it was completely solid and could not be turned.

I used 291 only . Ie no ptfe tape etc.

 

[ghostlymoron]

I've used PU 40 (its now been renamed) for several skin fittings. Easy to use, cleans up nicely with white spirit (when still soft), suitable for underwater applications and is very similar formulation to SIKA apparently but much cheaper. It is however a sealant/ adhesive which might make it difficult to remove next time. I'm very impressed.
Now called Puraflex 40 http://www.uksealants.co.uk/everbuild-puraflex-40-pu-40--p291.html

 

[sailorman]

In the old daze we used arborseal sealastic for everything

 

[VicS]

In the old daze we used arborseal sealastic for everything

the through hulls in my boat were fitted best part of 40 years ago using Sealastik. Still OK !

It seemed to be just putty in a tube. Certainly no poly this, that or the other.

 

[sailorman]

the through hulls in my boat were fitted best part of 40 years ago using Sealastik. Still OK !

It seemed to be just putty in a tube. Certainly no poly this, that or the other.

And it worked didnt it. Some get far to far under the bonnet

 

[MagicalArmchair]

I asked for clarification from Sika, they responded vaguely with:

Hello Mark,

We have in the past experienced compatibility issues using Sikaflex 291i with Bronze/Brass so we would suggest the use of Sikaflex 295uv.

Regards

James

 

[Alpha22]

Polysulphide sealant...... It's a sealant not a glue.... It sets underwater.... probably better than above!!

 

[pvb]

Bearing in mind Blakes seacocks are bolted in with 4 big bolts, you don't need any sort of adhesive. I'd be happy to use ordinary silicone sealant.

As for the loose transducer, you need to investigate why it's loose and check that the hole in the hull is the correct size for the transducer, rather than being too big.

 

[sailorman]

Polysulphide sealant...... It's a sealant not a glue.... It sets underwater.... probably better than above!!

And shouldnt be used on some plastics

 

[Alpha22]

And shouldnt be used on some plastics

Thankfully Blakes sea cocks are not plastic!!
Main issues surround ABS, PVC and Polycarbonate...... not often found under a boat.

 

[JakeMM]

Many thanks for all the replies!

The seacock is still attached to the wooden pad, so I'm tempted to leave that attached and so only worry about creating one new seal (the wooden pad to the inside on the hull).

In terms of the depth transducer, it's loose as it hasn't been properly fitted yet. It's the type that's stuck to the inside of the hull and so doesn't require a hole. I think I'll wait until the boat's afloat before I sort that though, so as I can check the best place to position it.