Skin Fitting Removal

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CJ13

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I plan to renew my below waterline Seacocks/ Skinfittings etc.
I suspect i'll need to grind the outer flange off the brass skin fittings to remove them.
There are various grades of grinder disc available - 60, 80 120 grit.
Which would be best for this job?

Thanks,
John
 
There has been a recent thread on this.
Personally I have had good results with a thick low removal rate angle grinder disc to take out all the circumference of the fitting where the flange section joins the tube. Others suggested a thin disc to quarter the flange then folding over with a chisel
Best idea I picked up was to use a dremel with cutter to take out a ring of the tube section of the fitting just inboard of the flange. Will try this next time
Martin
 
I had good results with a hole-saw just the right size to separate the flange from the tube. I sent my dad to B&Q to get them while I cracked on with the fittings that weren't jammed, and he came back with tile saws being all that were available in the right sizes. I was sceptical, but they actually cut through the brass very well, and could also cut sideways a bit when the hole wasn't quite in the right position.

Pete
 
prv said:
I had good results with a hole-saw just the right size to separate the flange from the tube. I sent my dad to B&Q to get them while I cracked on with the fittings that weren't jammed, and he came back with tile saws being all that were available in the right sizes. I was sceptical, but they actually cut through the brass very well, and could also cut sideways a bit when the hole wasn't quite in the right position.

Pete
Click to expand...
We used a standard hole saw, put a wood plug in the hole of the through hull to center the hole saw.

worked like a charm.
 
JFowler said:
I plan to renew my below waterline Seacocks/ Skinfittings etc.
I suspect i'll need to grind the outer flange off the brass skin fittings to remove them.
There are various grades of grinder disc available - 60, 80 120 grit.
Which would be best for this job?

Thanks,
John
Click to expand...

There is no mention of grit grade on my angle grinder disc nor in my ( Toolstation) catalogue.

I'd suggest a metal or general purpose disc.

The numbers you quote correspond with the grades of sanding disc however . :confused:


I believe however that a hole saw works very well.
 
Strange, you all tackling the job for outside, sounds like a good plan, when I did mine last year I just used a cutting disc in the angle grinder and chopped through the flange nut INSIDE the boat. In most cases I had to use the same cutting disc to cut the seacock from the skin fitting first, then the skin fitting just pushed out through the hull.

I like the idea of a wooden plug and the hole saw, sounds very neat.
 
The easiest way to remove skin fitting with minimal risk of damaging the hull is to use a Dremel type tool with a reinforced cutting disc. The disc is used to cut away the flange just level with the hull; the flange then drops off and you can withdraw the remainder of the fitting into the boat. Takes about 3 minutes and is easy to control, unlike the time I tried to use an angle grinder to do the job and had to do some repairs to the hull before the new fitting could go in.
 
I took your intended approach using a 4" angle grinder with a 60 grit sanding disc on a rubber backing pad. If you hold the grinder at an angle away from the hull and focus your work on the hole of the skin fitting you will sand the material away from the centre of the skin fitting in a concave fashion and therefore avoid any damage to the hull outside of the circumference of the flange. The material gets very hot however so you need to complete the job fairly briskly once committed.
 
knuterikt said:
put a wood plug in the hole of the through hull to center the hole saw.

worked like a charm.
Click to expand...

Yep, that's exactly what I did, and worked just as well :)

Only exception was the one where the saw was slightly too small for the fitting, so it merely bored out the tube to a wider diameter rather than cutting the flange off. But the tile saws had the same "diamond" grit around the barrel of the saw as they did on the edge, so I was able to rock it from side to side and cut a wide enough hole to break through.

Pete
 
ghostlymoron said:
Why not just use stillsons and unscrew the retaining nut? Much less mess and risk of damage to hull.
Click to expand...

Well, my stilsons are about two and a half feet long, and I am not a small bloke, and I still couldn't shift the nut on the 2" poo pipe outlet. If you'd been there on the day and thought you could do any better you'd have been welcome to try.

There were several smaller ones I couldn't shift either, but that was partly due to not being able to get a decent swing at it, eg in a locker too small to fit the stilsons in (still had a pretty big AJ though) or under a moulding where I was having to work at arm's length and couldn't get any decent leverage.

It took about two hours for my dad to drive to B&Q and back to get the hole saws, so it wasn't a procedure we adopted lightly.

When I changed the cockpit drain fittings on KS three years ago, out of curiosity I took the bits home and tried to undo them on the bench, with the benefit of plenty of space and a big vise to hold them at a convenient angle. Still couldn't shift them, gave up when I'd put a pipe over the spanner handle and it felt like I was about to rip the wall out of the side of the shed (the workbench is bolted to it).

I managed to unscrew one skin fitting on Ariam; for the others the holesaw was the only option.

Pete
 
prv said:
I had good results with a hole-saw just the right size to separate the flange from the tube. I sent my dad to B&Q to get them while I cracked on with the fittings that weren't jammed, and he came back with tile saws being all that were available in the right sizes. I was sceptical, but they actually cut through the brass very well, and could also cut sideways a bit when the hole wasn't quite in the right position.

Pete
Click to expand...

Yep worked for me.
 
I fitted new thru-hulls last year - It took a lot of work to cut the existing fittings free - using a reciprocating “Fein” tool, new to me, but a very useful implement of destruction. This tool is referenced in the May issue of PBO, p59 and p75. Less likely to end in grief compared to an angle grinder, IMHO. The job was done from the inside, filings localised (again compared to an angle grinder).
 
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