# Removing old/corroded seacocks



## Beersmith (Nov 5, 2008)

I had trouble finding an article instructing how to do this, so I wrote about how I did it and would like to share:

One of the things I knew about Windsong when I first saw her was that all of the seacocks needed to be replaced ASAP. They are very old-school style Groco seacocks and all have corroded to the point where they are inoperable. What does that mean? If a hose were to leak, I would not have had a way to shut off the thru-hull and the boat would probably sink unless the hose or seacock was plugged.

Seacocks are meant to be the #1 insurance on the boat against sinking, and I didn't have that insurance for the entire time I owned the boat in the water. Since I started the bottom job I have been contemplating how the heck to get the seacocks and thru-hulls off the boat. They were so corroded that unscrewing the thru-hull from the seacock was impossible. I spent many months contemplating my approach and did as much research I could on the subject. Unfortunately there aren't many articles written on how to get this job done on old, corroded equipment. There are plenty of articles on how to take apart modern seacocks, but non on how to tear apart old ones with no hope of reuse.

I did, however, find a few blogs and forum posts from people who just cut the thru-hulls up with a Dremel or some other tool to help remove them. But with my limited experience in doing things like this, I really needed a step by step instruction on how the heck to do that. After some creative thinking and experimentation, I finally figured out how to do it and here I will show my process.

Here are the seacocks in the head with hoses removed. One is the sink drain, another is for the head itself, the other was unused with no plumbing coming from it.










Here are the thru-hulls attached to these seacocks










Each seacock has two bolts that go through the hull that needed to be removed. My dad and I began this job back in May by removing the hoses to the seacocks and the bolts that go through the hull. Once we reached that point, we were stumped as to how to remove the thru-hull from the seacock. So after my research I took a stab at cutting the thru-hulls to remove the mushroom head so I could just pull the seacocks out from the inside.

I removed the three thru-hulls from the head seacocks before I got down there with the camera, so the sequence below shows the thru-hull from the galley sink. As you can see, the two bolts are still attached so I wasn't able to actually remove that seacock until I get a second hand, but the process is still shown.

First, using a cut-off wheel on my Dremel tool, I made a series of cuts to create some pie wedges. For the bigger thru-hull in the head, I needed to make a few more slices.










In my research I learned that bronze is a pretty soft metal, so cutting and bending is quite easy. In this next step, I hammered a scraper/chisel under one of the slices and pulled down to bend the slice outwards a little bit, enough to fit the back of a hammer under the slice.










With the hammer under it, pry the piece right off. The pieces pried off surprisingly easy.



















Repeat the process for each slice until all you have left is a the clean shaft of the thru-hull in the hole.



















At this point I went inside and removed the seacock by just pulling it out. One seacock just fell off after cutting the mushroom, one needed to be pried off with the back of the hammer, and the other just needed some muscle to pull out. Here is the head area with all removed:

Outside:










Inside (thats a flashlight in the middle):










Old seacocks. You can see how corroded they are, no hope for the valves to turn. They are not the newer style Groco seacock with a locking nut on the base.



















After figuring out this process, removing these things is a piece of cake. I'll need some help to get the remaining seacocks unbolted, but I am no longer worrying about the process when comes time to start fairing and repairing the bottom.

I'll be using these articles as reference to install new thru-hulls and seacocks (links):

Seacock and Thru-Hull Primer
Replacing Thru-Hulls and Seacocks
Seacock Backing Plates


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## mitiempo (Sep 19, 2008)

You did a good job. I also use a Dremel for many things on the boat. But an angle grinder would have made fast work of that job. 

The links you are using to replace them (by Maine Sail) are excellent.


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## mixmaster (Feb 12, 2003)

I had the same issue on my downeaster, same seackocks. I used an angle grinder and ground the heads right off. It took me about 5 minutes per.


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## jamesnewsome (Jul 30, 2000)

Excellent post, thanks for the detailed info and photos.


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## RichH (Jul 10, 2000)

Angle grinders make quick work of through hull + seacock removal, BUT, you can easily overheat the surrounding FRG. 
So, for 'recalcitrant' grinding (especially for TRUE bronze that has the absolute minimum of zinc component, zinc added for ease of 'machining'. Without zinc, bronze is a 'b!tch' even to 'grind') the hacksaw method combined with or in combination of the angle grinder method is a good way to remove and not 'overheat' the FRG. 

The better and more expensive alloys of bronze have very little zinc, and a very hard to grind, cut, or machine. NiAl-Bronze is probably the 'hardest'; most of what you find on rec. boats is really a 'Red Brass' because its loaded with zinc to make it cheaper to machine, and is therefore easier to cut or grind - but you better have sufficient zinc anodes elsewhere because if you dont the zinc within the Red Brass (faux bronze) will become the 'anode'.


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## Maine Sail (Jan 6, 2003)

RichH said:


> The better and more expensive alloys of bronze have very little zinc, and a very hard to grind, cut, or machine. NiAl-Bronze is probably the 'hardest'; most of what you find on rec. boats is really a 'Red Brass' because its loaded with zinc to make it cheaper to machine, and is therefore easier to cut or grind - but you better have sufficient zinc anodes elsewhere because if you dont the zinc within the Red Brass (faux bronze) will become the 'anode'.


Most good quality UL Marine rated seacocks are made from 85 three 5 bronze which has very little zinc. Apollo, Groco, Spartan and many others use 85-5-5-5 bronze which is supposed to have less than 5% zinc.


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## RichH (Jul 10, 2000)

TRUE bronze has nil or trace % zinc ... and is an absolute ROYAL and expensive PITA to machine.


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## Maine Sail (Jan 6, 2003)

RichH said:


> TRUE bronze has nil or trace % zinc ... and is an absolute ROYAL and expensive PITA to machine.


I don't know of anyone in the marine industry that ever used true bronze with no lead or zinc for machining. Seeing as bronze is a copper alloy I don't even know what a true bronze would be? Perhaps just tin & copper? Considering that nearly every maker of seacocks from Spartan to Apolo, Groco & Buck Algonquin has used 85 three 5 bronze and it is about the most resistant to dezincification we see in the marine world I would have to consider that a good marine bronze. Prop & shafting bronze has a LOT of zinc unless a NiBrAl prop...

As you said very tough stuff even at 85 three 5. I have seen 40 year old bronze seacocks clean up and look like new with no signs of pitting or dezincification and continue on. Well made bronze seacocks will last a long, long time. You can still buy Spartan's but they are getting expensive.

I cringed at the OP discarding those beautiful old seacoks because I have restored ones that looked just like that to near new condition provided there was no dezincification. It is rare that I have seen deszincification on a true 85 three 5 bronze. Verdigris yes, dezincification very rarely...


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## Beersmith (Nov 5, 2008)

Maine Sail said:


> I cringed at the OP discarding those beautiful old seacoks because I have restored ones that looked just like that to near new condition provided there was no dezincification. It is rare that I have seen deszincification on a true 85 three 5 bronze. Verdigris yes, dezincification very rarely...


I'm still holding onto them. I figure I could get something for them, or restore them myself some day. I will be buying new ones for my boat though.


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## Sabreman (Sep 23, 2006)

Excellent job and a very creative solution. I'm not sure what I would have done in you shoes, but now I have a great idea filed in my cluttered memory. Good work!

One suggestion for the future is that when using the hammer, use a piece of 1/2" plywood as a backer. This will prevent distortion of the underlying material. In this case, it didn't matter because the hull was clearly thick enough. But if you were removing something on a nice wood like teak ply, you could end up with indentations or crushed material.

Just a habit that I've formed after buggering too many surfaces (wallboard, fine wood, etc.)


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## tominny (Aug 30, 2011)

I have been battling with the same issues and was afraid to do something that would muck up the boat. Your post is spot on. Thanks!


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## skygazer (Sep 3, 2011)

Maine Sail said:


> I have restored ones that looked just like that to near new condition provided there was no dezincification. It is rare that I have seen deszincification on a true 85 three 5 bronze. Verdigris yes, dezincification very rarely...


Maine Sail, if you happen to see this, how did you free up the stuck valves? I have some in the head area of an older boat I purchased last fall.


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## Maine Sail (Jan 6, 2003)

skygazer said:


> Maine Sail, if you happen to see this, how did you free up the stuck valves? I have some in the head area of an older boat I purchased last fall.


Loosen the cone adjusting nuts and tap them lightly with a soft lead hamemr or soft brass hammer. Do not it too hard, you don't need to, and the cone will pop free. A little PB Blaster in there won't hurt either.

Feel free to read this:

*Servicing Tapered Cone Seacocks*


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## Capt Len (Oct 9, 2011)

Those little bumps on the inside of the inlet take the bite of a steel bar inserted into the threaded thru hull. A 36 inch pipe wrench on that and it unscrews tout suite.The two screws keep the seacock from turning. Then remove them. The barrels of those seacocks can be lapped in situe with "lapping compound" and greased to last until about 2045.They are probably gun metal (mostly copper with tin. cannon material) Navel bronze types have a lot of zinc and some arsenic to stabilize it Good quality bronze with SS ball ball valves and polyethylene or nylon seals are the norm today. They require really good backplates to support the thruhull part.(on another thread) Longer lever, bigger hammer.Works on old fishboats.


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## skygazer (Sep 3, 2011)

Thanks for your responses, guys. I've not seen the insides of the valves, so I'm a bit unclear about the application of your knowledge, but the worst that can happen is I destroy the valves. Boat is on a trailer in the backyard, so no big deal.

It's zero F. weather so nothing will be happening for awhile.

Edit: Upon reflection, I do happen to have a 36 inch pipe wrench. And, a 48 inch one just in case.


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## Frank1951 (Oct 27, 2010)

Perfect!!! I have a very similar problem and the seacocks you picture appear to be identical to the ones I have on my Downeaster 32. Although my seacocks are still operable, the threaded street L on the output side of the head is not a proper hose barb and has an outside diameter that is slightly too big for the 1 1/2" hose. The whole thing is generally so corroded that I am replacing the vintage seacocks with new modern ones while I am hauled out for other repairs. Great sequence of pics and procedures. Thanks


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## ambianceack (Aug 27, 2006)

I just pulled two seacocks out of my boat this weekend. I used a wrench thru hull mall. it fits from 0.75" to 1.5" thru hulls. Just line up the grooves with the tangs on the inside fo the thru hull, along with a 12-inch cresent wrench and two foot pipe2 inch inside dia.) for leverage, turn to the left since lefty loosey and came right out. The thru hulls are the old wilcox crittenden and original to the 34 year old boat.


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