Through hull fitting

[sailaboutvic]

Through hull fitting .
I can't remember last time I change one , many moons ago , there a chance that I may this year , you only tend to get one chance to get it right other wise the Hauling in and out again can soon mount up .
So here the question ,
A . Would you put sealer around the fitting and screw it up tight .
B. would you put the sealer on the fitting and hand tighten it leave till it partly gone off and then tighten it up tight .

 

[macd]

Morning Vic.
Sika suggest the latter, although I'm not entirely sure it makes much difference. Obviously if you do 'B', then it's crucual that on the second tightening only the internal nut turns and not the through-hull.

If it's the sort of through-hull with two internal ribs for holding it in place, a handy holding tool an be contrived from a socket: buy a cheap one with an OD such that it will slide fairly snugly into the skin fitting. Angle grind two slots in the socket such as to engage on the ribs...voila, one cheap and effective holding tool.

Obviously you deserve a cold one after each and all of these tasks :encouragement:

 

[Networks]

Hi Vic,
I am replacing my through hulls in a couple of weeks myself.
On my last boat the yard replaced them, they sealed with Sikaflex and tightened up fully, if you seal then tighten again when its partly gone off you can damage the seal, I guess it depends just how much it has gone off. I accidentally turned one the following day while fitting a sea cock and had to remove the through hull and seal it again.

macd is right about the holding tool, very handy to stop the trough hull turning, we jammed pliers or something in if I remember to do the same.

Forgot to mention, I have read somewhere on these pages that you should not use Sikaflex to seal them, in that case what should you use?

Best of luck Kevin MdR L34

 

[macd]

I have read somewhere on these pages that you should not use Sikaflex to seal them, in that case what should you use?

Beats me. 'Sikaflex' isn't terribly meaningful, of course, since it encompasses at least eight different products. Sikaflex 292 is specifically recommended by Sika for through-hulls. 291, which probably gets plenty of use for the same purpose, isn't.

 

[Tranona]

If you ever want to get the fitting out again without grinding the flange off, then a polysulphide such as Boatlife or Arbro is a better bet as it is does not set hard and seals just as well as polyurethanes.

 

[vyv_cox]

I agree, tighten it fully first time. It is far too easy to displace something on a second tightening, possibly destroying the seal.

 

[sailaboutvic]

Thanks for the info guys ,
Kevin was going to pop round to see you but I came down with a bad case of the flu and don't want to pass it on .

 

[ghostlymoron]

I've fitted loads of through hulls and always tightened them fully initially using Sika or equivalent except on NASA fittings when I've used silicone. None has ever leaked. Re- tightening is unnecessary and risky.

 

[x25dave]

OK !!! Confession time :ambivalence:

2 years ago, whilst lifted out for pre season antifoul, I decided to renew the skin fitting for my speed log, as I was fitting a new head, which needed a new paddle wheel, which did not fit the original skin fitting.
I slightly enlarged to hole to accept the slightly larger fitting, applied a little sealant, and shoved it through the hull. It stuck there whilst I went aboard, and applied the nut. This nut had little bumps on it, which perhaps should have been a warning, but I got the Molegrips on, and tightened it well down!!
The following season, at sea, I noticed that the speed log was stuck on 0 MPH, so I went below to remove the paddle wheel, free it off, and refit it. A simple procedure, done it before, piece of cake.
Having undone the cap, holding the paddle wheel in place, I pulled the wheel out, and was rather shocked to see the skin fitting sheer off!!!!!!! I was looking at a 35mm hole thru the bottom of the boat!!!!!!
I had bung nearby, with which I stopped the gushing water, and headed ashore. Dried out against a wall, whilst i located, and purchased a replacement skin fitting.
This time I did it up hand tight!!!!!!!
I had way over stressed the nylon fitting when I tightened the first one.
The only pressure, to speak of, on the fitting is inwards, it doesn't need to be wound down too tight. :encouragement: