3/4" Skin Fittings Holes Cut too Large...........Options???

superheat6k said:
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When tightening the Sika seal just nip up gently so it is squeezing all around the fitting, but do not pull it up too tight yet. Let it set for a week then pull up firmly onto the set Sika, which will by then form a proper gasket.
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This is very good advice. If you nip it up tight onto uncured sikaflex, you will squeeze most of it out and may not get a good seal, but doing as described will give you a good seal. All my Tru Design fittings were sealed that way, and none have leaked.
 
Tranona said:
You hear both because there are sound arguments for both approaches and therefore strong advocates for either one or the other. Personally I don't think it matters in this case provided there is plenty of sealant and the nut is tight.
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But if you hand tighten initially then fully tighten when the sealant has set what you must do is counterhold the fitting so that it does not turn and break the bond between the fitting and the hull while you finally tighten the nut
 
viago said:
i'd smear some epoxy resin and glass around the inside edges of the hole to reduce the diameter a bit, tidy up the outer edge with a bit of gelcoat and use plenty of ct1 to seal the new skin fitting in. a washer on the inside to spread the load is no bad thing.
probably over kill but what the hell.

one question i have is in tightening up the skin fitting as i have heard conflicting advice. does the team recommend tightening the fitting fully in the first instance or tightening to a little over hand tight and murdering up after the gunge has set?
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You would seriously do all of that for a hole that has a 1mm clearance ?

Where is all of the resin, mat and CT1 going to go ?

After you have "reduced the diameter a bit" you will need to file it all off again to get the fitting in the hole.
 
Regarding tightening, or not...........

If you were bolting two flat surfaces together you would lightly tighten, then fully tighten when cured. This would be in a situation such that the sealant is acting as a gasket.

With fittings such as a through hull it would be a bad idea. If the fitting turn you lose the seal. If the fitting is pulled harder into the hole, you lose the seal. For a through hull put sealant on all the outer flange, where it will come into contact with the hull and plenty between the body and the sides of the hole, push it through the hull, make sure the gap between the body and hull is still full of sealant, apply sealant to the inside of the hull and screw the nut down tight. That's tight as in moderately tight, a bit more than hand tight, not gorilla tight. When the sealant cures leave it alone, it'll all be stuck together like shit to a blanket, it will not leak or fall out.
 
PaulRainbow said:
You would seriously do all of that for a hole that has a 1mm clearance ?

Where is all of the resin, mat and CT1 going to go ?

After you have "reduced the diameter a bit" you will need to file it all off again to get the fitting in the hole.
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of course i wouldn't do that for 1mm play, i dont go looking for work. the op didn't mention 1mm, is that a figment of your imagination? must have been a very deep and thin walled hole saw if that's the case.

i dont know what the gap is so i answered the question as if i was unhappy with the slack around the new fitting. is that a problem for you?

if i'd have sawn out the skin fitting i'm pretty sure i'd have had a lot more missing material than that.

luckily i've managed to remove my metal ones with brute force, a lock nut, stilsons and a lump hammer and i've cut and broken the brittle plastic ones out without damaging the hull too much so my answer is purely hypothetical.
 
PaulRainbow said:
Firstly, what a daft way of removing a through hull !

If there is only 1mm of pla all around the fitting there is nothing to worry about, stick it in with sealant, end of.
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The Raw Water Inlet and Head sink outlet were heavily corroded and the raw water In a really stupid place all things considered with no real access!!!! Not sure the designers at Westerly appreciate it was gonna need changing after 10 years................
 
Thanks for all the good advice!!!! the boat had been sitting since 1997 but she is almost now completed. It's really a question of piece of mind. If I had a better option than cutting them out I would of used it and believe me when I say I tried but access was not great. The holesaw used did cut very close to the thruhull threads and at max is 1-2mm play and there is certainly enough flange on the outside covering the hole.....

Regards
 
snowbird30ds said:
Put an o ring round it to take up the slop then use loads of sealant.
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Now that an interesting thought.

Thinking about the all the applications that O-rings are used in Engineering why not just use an O-ring to seal the skin fitting between the outside of the hull and the outer flange of the skin fitting.

When I was rebuilding my Engine raw water heat exchanger the end caps and the inner tube stack was sealed with O-rings. The top of most raw water strainer lids are sealed with O-rings and O-rings are used on alot of hydraulic fittings at a mush higher pressure that the submerged water pressure on a boat skin fitting.

No messy sealant required and much easier to replace when time comes specially if Brass fittings are used instead of bronze or stainless steel.
 
thesaintlyone said:
Thanks for all the good advice!!!! the boat had been sitting since 1997 but she is almost now completed. It's really a question of piece of mind. If I had a better option than cutting them out I would of used it and believe me when I say I tried but access was not great. The holesaw used did cut very close to the thruhull threads and at max is 1-2mm play and there is certainly enough flange on the outside covering the hole.....

Regards
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If you ever have to do this job again, you do not need access from the inside. You can either grind the outside flange off carefully with an angle grinder or bung the hole and use a hole saw from the outside. Then just knock the threaded part into the boat. Saves all that hassle you went through.

Anyway just put the new ones in with plenty of sealer and enjoy a well earned beer.
 
Just say that the extra sealant is there to allow for thermal expansion of dissimilar materials, the sizes you are talking about are small enough not to matter.:encouragement:
 
Buy TruDesign and epoxy the plastic fitting into place. This is the recomended way for the TruDesign fittings.
 
viago said:
of course i wouldn't do that for 1mm play, i dont go looking for work. the op didn't mention 1mm, is that a figment of your imagination? must have been a very deep and thin walled hole saw if that's the case.

i dont know what the gap is so i answered the question as if i was unhappy with the slack around the new fitting. is that a problem for you?
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Nope, not a problem for me at all, neither is reading what the OP typed.

I guess reading post #8 was too much for you ?
 
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