What sealant underwater?

[Spyro]

I am fitting a new lower rudder bearing and want to bed the brackets which hold the 2 halves of the bearing onto some type of sealant when re-fitting, this will also fill the small space around the bracket which I will then cut flush with the skeg before epoxying over it all. This is how it was when I took it appart.
I am worried about using Sikaflex in case I have to remove them again ( bracket has to come off to remove the rudder) Are there other sealants that I could use underwater?

Thanks

 

[vyv_cox]

Sikaflex 291 will be perfectly OK. It is very good stuff, but not so good that you won't get it off again. Despite what you may read here, all my light aluminium window frames are bedded against the coachroof with Sikaflex 291 and they come off without too much of a struggle. With a heavy fitting such as yours it's the ideal sealant and you will have no trouble at all releasing it with wooden wedges.

 

[tel1]

totall agree with above

 

[VicS]

I dont know if this is a sensible suggestion or not but:-

If you don't want the sealant to stick the bracket in place, as Sikaflex will tend to do, you could perhaps lightly grease its surface before fitting (silicone spray even)

 

[JohnTH]

Well, this is a job that Denso tape is good for.

Put as many layers of tape on as to make up a gasket. In this case just one should do. Make holes for the bolts and assemble, job done.

73s de

Johnth

 

[dratsea]

I am fitting a new lower rudder bearing and want to bed the brackets which hold the 2 halves of the bearing onto some type of sealant when re-fitting, this will also fill the small space around the bracket which I will then cut flush with the skeg before epoxying over it all. This is how it was when I took it appart.
I am worried about using Sikaflex in case I have to remove them again ( bracket has to come off to remove the rudder) Are there other sealants that I could use underwater?


Thanks

Silicone comes off a treat but we are advised that it should not be used underwater because it will degrade. It does, but if a bit of degradation will not cause problems (=leak)then use silicone. I partially insulated an anode on the bottom of rudder and 10 yrs later, there was still a waterproof seal but the anode remains peeled off easily.

 

[Tranona]

I have always used a Polysulphide (Boatlife caulking) for this kind of application. Seals well, is stable, but easy (relatively) to take apart.

 

[bromleybysea]

I fitted a new aluminum fore-hatch recently and the instructions stipulated polysulphide sealant because it is easy to get the thing off if you need to.

 

[Dan the man]

Lifecalk is good, along the same lines as Sikaflex 291. Your particular area of application will allow you to get a knife blade up there to cut it free.

Im guessing it will flex, the sikaflex will allow it to flex and not break the seal.

 

[xtiffer]

You can always go the traditional way and use red lead putty.
It worked OK for William Fife but I suppose that is politically incorrect now in UK.
Cheers,
Chris

 

[vyv_cox]

Well, this is a job that Denso tape is good for.

Put as many layers of tape on as to make up a gasket. In this case just one should do. Make holes for the bolts and assemble, job done.

73s de

Johnth

Not quite sure why you think Denso tape would be good for this? It's superb stuff for corrosion protection, the motor of my windlass is wrapped in it. We used it for corrosion protection of tubulars underwater on offshore platforms very successfully. But as a gasket or sealant in these circumstances I can't see what it offers, as it has no adhesive properties whatsoever.

 

[KellysEye]

I'g go with Sikaflex. You can get it off - use a knife to cut most of it away, take the remains off with Acetone. Bear in mind to get a good seal tighten the the nuts to one thread back from the last thread, let it dry, then tighten the last thread.

 

[doug748]

I should grease up those nuts and bolts, then you could use silicone under the brackets and blag car body filler on top and fair up. This works, is minimum fuss and easy to chip out later.
The traditional red lead putty sounds good as well, is it similar to the linseed oil stuff we put in our windows?

 

[ghostlymoron]

Do you really need sealant? Sealants are to keep water out - as in sealing around skin fittings. If you just need something to bed the bracket on so that you get an even bearing surface, you could use a traditional rubber gasket, cut from an car inner tube that you can get from a tyre repair depot for nothing. Cheap, non-messy and easy to dismantle!
I use these under winches as well.

 

[LittleShip]

Well, this is a job that Denso tape is good for

Good idea, Denso is a Vaseline type substance that will remain flexable for years and easy to remove in the future, there is another product if you can find it which was made for the domestic market called Sylglas, its the same product but priced differently.

You can always go the traditional way and use red lead putty.

As Xstiffer says the traditional materials have proven track records.

Tom