struggling with thru-hull removal

xort · #1 (**permalink**) 11-26-2008

I have an old Groco SV thru-hull & seacock that needs replacing. There is no room above the seacock to unscrew it upwards and off, so the thru-hull HAS to be unscrewed down and out. I torched it to break it free and it did rotate maybe one degree before the dogs inside broke off. I've got PB blaster soaking in it for now.
But I am stumped on how to get this apart. Grinding off the mushroom isn't an option because I'd then need to raise it up from the inside and like I said earlier, I don't have any headroom to do that.
One idea I'm considering is grinding opposing flat spots on the mushroom for a pipe wrench to grab. But the mushroom doesn't stick out very far so this won't be easy.
And there is no room under the floorboards to get a sawz-all or grinder on any part of the seacock. Terrible installation.

Any good ideas on how to unscrew the thru-hull now that the dogs are broken off?

bubb2 · #2 (**permalink**) 11-26-2008

Sell the boat and shoot the guy that put it there. LOL

badsanta · #3 (**permalink**) 11-26-2008

Bronze is soft. Get an electric sawzall or a hack saw. Cut between the valve and the thru hull. Or cut the valve in parts. It wont take long. Just cut it out. Take out the valve and then cut the nut to the thru hull or once the valve is gone stick the saw blade into the thru hull and cut it in two places 180 degrees apart dont cut too deep to the hull and take the two halfs out. Good luck.

mangomadness · #4 (**permalink**) 11-26-2008

dremel with a cut-off wheel

Maine Sail · #5 (**permalink**) 11-26-2008

Quote:

Originally Posted by xort

I have an old Groco SV thru-hull & seacock that needs replacing. There is no room above the seacock to unscrew it upwards and off, so the thru-hull HAS to be unscrewed down and out. I torched it to break it free and it did rotate maybe one degree before the dogs inside broke off. I've got PB blaster soaking in it for now.
But I am stumped on how to get this apart. Grinding off the mushroom isn't an option because I'd then need to raise it up from the inside and like I said earlier, I don't have any headroom to do that.
One idea I'm considering is grinding opposing flat spots on the mushroom for a pipe wrench to grab. But the mushroom doesn't stick out very far so this won't be easy.
And there is no room under the floorboards to get a sawz-all or grinder on any part of the seacock. Terrible installation.

Any good ideas on how to unscrew the thru-hull now that the dogs are broken off?

Carefully grind the mushroom head off the thru-hull with a 4" angle grinder. Then go inside an simply pull the valve to the right or left and it should tip free. If not cut the valve off the thru-hull inside the boat and the use a pipe wrench on the threads of the thru-hull to twist it out..

PB Blaster won't do much of anything to 5200 you'd be better off to try DeBond.. Now you can understand why many folks are opposed to 5200..

jrd22 · #6 (**permalink**) 11-26-2008

Xort- would you have enough room to get a small die grinder in there to cut the valve off? You would need an air compressor so shore power would be necessary, not sure of your situation. I'm pretty sure you can rent small pnauematic grinders, maybe even right angle ones if you don't have one. Hard to figure out without seeing it. Good luck.

PorFin · #7 (**permalink**) 11-26-2008

Xort,

The above options look quicker and easier, but if they don't work for you here's another.

Carefully grind a couple of slots on either side of the mushroom across the center of the through hull. You'll then (hopefully) have a place for a piece of 1/4" steel plate to gain purchase and act as a really big screwdriver head. Add a pipe wrench (one inside around the seacock) and a big adjustable wrench (on the steel plate) and give it a turn. You may need to add an extension (like a pipe) to the adjustable wrench to get enough leverage to get things moving.

xort · #8 (**permalink**) 11-26-2008

There is absolutely no room inside the boat under the floor to get at the seacock. And besides, they ran all kinds of wires around the seacock that I hope to move after it is off. If I start running a sawzall I'll cut some wires for sure; antenna wires and other stuff I do not want to splice.

There aren't any bolts to the flange on this Groco. I think I can see threads of the thru hull looking down into the side of the seacock. I have the big rubber plug out of the seacock. Am I wrong in thinking the seacock is threaded directly into the thru-hull? How long is this threaded area likely to be? From what I can see it looks like maybe an inch of threads into the seacock.
I have zero room to unthread the seacock upward off the thru-hull; I have to unscrew the thru-hull downward out of the hull & seacock.

Cutting a notch in the mushroom is similar to my idea of grinding two flat spots to accomodate either a pipe wrench or a big set of slip joint pliers. I'm afraid I won't get a very deep & neat slice to make a tight fit for the big 'screwdriver'.

I was using PB blaster to free the threads between the seacock & the thru-hull.

What am I missing?

sailaway21 · #9 (**permalink**) 11-26-2008

If you take your grinding wheel and place it across the opening of the mushroom hole, with the wheel perpendicular to the hole, you should be able to grind a couple of 1/4" slots as PorFin suggests. Then just get a piece of 1/4" plate and cut/grind it so it will fit in the slots. You'll avoid risk to the fiberglas around the mushroom head that way. You should be able to grind two or three separate sets of slots if you round out the initial ones. There should be a compression ring, that you might not be seeing that holds the mushroom headed thru-hull secure...not the seacock.

Rockter · #10 (**permalink**) 11-26-2008

Do you have a picture or two Xort?