Removing seized skin fitting

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yachtorion

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What's the best way to remove a metal skin fitting where the backing nut has seized to the fitting and both rotate together?

There are no obvious slots in the mouth of the fitting.

I'm considering making a mess of the outside with an angle grinder then whacking it from inside with a large hammer in the hope of removing it internally.
 
yachtailsa said:
What's the best way to remove a metal skin fitting where the backing nut has seized to the fitting and both rotate together?

There are no obvious slots in the mouth of the fitting.

I'm considering making a mess of the outside with an angle grinder then whacking it from inside with a large hammer in the hope of removing it internally.
Click to expand...
cut / drill through the backing nut will allow the fitting to drop away or cut slots through the outer flange @ 90 deg to the hull
 
The easiest way is to use an angle grinder with a small disc, and grind off the angle between the flange and the hole. Do it carefully, and there'll be no damage to the hull, the flange can be removed, and the rest of the fitting knocked through into the inside of the boat.
 
I had a similar problem and removed the skin fittings by hammering a wooden block into the outside of the fitting.
Then use a metal hole saw, which is equal to the diameter of the threaded tail fitting (not the flange size) to cut off the flange.

Much neater and easier to control than an angle grinder.

Flange pops off, then push the fitting inside. Done.
 
pvb said:
The easiest way is to use an angle grinder with a small disc, and grind off the angle between the flange and the hole. Do it carefully, and there'll be no damage to the hull, the flange can be removed, and the rest of the fitting knocked through into the inside of the boat.
Click to expand...
+1. This is best method if you are careful. The assembly can be lifted into boat once the outer flange has fallen off.
 
I tried the angle-grinder technique, as pvb and other describe, for the first time at the weekend. A bit nerve wracking having an angle grinder so close to the hull, but it worked. Took about 25 mins for the complete removal, which is a lot quicker than trying to cut through the nut in an awkward confined space.

Be very careful, so that you just say break through at the angle where the flange meets the pipe part of the skin fitting. Once you've removed most of the strength you can waggle the skin fitting a bit from the inside, which should give you enough to gentle get a screw driver under the remains of the flange and lift it off.

It was easy to pull the skin fitting with old seacock attached in from the inside. It was quite warm to the touch though.

No marks at all on the hull, but be careful.
 
+1
Small angle grinder with metal cutting disc used from outside carefully. Two cuts in an X, then two more at # and slight prying and wiggling will let you break off the outside rim in segments, no hammering needed and if you are careful and do it gently not a scratch on the hull. I did mine this way because of really awkward big spanner access inside, first one took maybe 10 minutes to remove, others a couple of minutes each once I had the knack.
 
Endorse the 'small' 115mm angle grinder with cut-off disc. Was very trepidatious, like others, but it turned out to be easy.... with a little care. Did two....
 
1. Pack with wood, centre drill and use a hole cutter carefully to cut away flange.

2. Carefully grind away flange with angle grinder.

3. Use small Dremel with cutting wheel attachment and cut from inside the fitting between the flange and nut. Small cutting wheels available from Screwfix on Internet BUT not in their catalogue.

I have only used method 2 but was going to try 3 as had to remove a 1yr old fitting that had corroded due to fault. Still awaiting response from supplier.
 
Grind off the flange, as suggested - with a small disc to get inside a bit. Go on, it's manly and such fun, like Nov 5th. Gloves and goggles and mask off the surround gelcoat to stop any damage from the sparks. The metal is very soft under the disc so hold firmly but touch gently; you'll see the gap between the flange and the thread begin to open so move round as soon as it does.
 
kennyh said:
use a metal hole saw, which is equal to the diameter of the threaded tail fitting (not the flange size) to cut off the flange.

Much neater and easier to control than an angle grinder.
Click to expand...

+1

I'm sure the angle-grinder way works fine, but this is neater and less dramatic. I've found that abrasive-tipped hole "saws" intended for bathroom tiles work particularly well - with no teeth as such to flick it around, the tool is very smooth and controllable. This means that with the right size saw and if the skin fitting has a slight bevel around the hole, you don't need anything (like a wooden plug) to provide a centre - just put the drill against the fitting and away you go. The abrasive grinds through brass and bronze quite easily.

Pete
 
Thanks all. For no other reasons than 1) I have the grinder and discs but no suitable wood to pack the fitting with to control my standard jumpy holesaws and 2) I was practising with the grinder yesterday and seemed to be able to mostly control it, I'll go with the grinder. I'll update with the results :)
 
yachtailsa said:
Thanks all. For no other reasons than 1) I have the grinder and discs but no suitable wood to pack the fitting with to control my standard jumpy holesaws and 2) I was practising with the grinder yesterday and seemed to be able to mostly control it, I'll go with the grinder. I'll update with the results :)
Click to expand...

You'll find the metal is very soft and grinds away very easily with hardly any sparks (assuming a type of brass and not SS). Its far easier to do than you think - just brace the grinder (wear goggles of course) well with both hands (anchor your forearms or elbows on the hull for stability if that helps) and touch the surface to be cut with the wheel - no need to push hard.
 
yachtailsa said:
What's the best way to remove a metal skin fitting where the backing nut has seized to the fitting and both rotate together?

There are no obvious slots in the mouth of the fitting.

I'm considering making a mess of the outside with an angle grinder then whacking it from inside with a large hammer in the hope of removing it internally.
Click to expand...
Drill a hole or two in the nut and break it off of the fitting?
 
cut the skin fitting right down to the nut.
This leaves just the nut to cut off.
Use a small angle grinder or a dremel to cut down both sides of the nut and skin fitting.
Then just prise apart nut and knock out skin fitting from inside.
 
aquaholic said:
had to do this a couple of weeks ago on my project, video here: https://youtu.be/vqg_4OjBQCI
Click to expand...

OK if it works for you, but that way you are putting the disc so near the grp that damage seems certain; the grinder method suggest above grinds away at the hole in the flange until it is just thinly detached from the thread part, so the disc never touches the grp.

I like the sound of the abrasive hole saw but you'll need the exact size.
 
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