Removing Old Seacocks and Through Hulls

I've read the excellent Compass Marine how-to articles and am getting closer to a go/no-go decision on replacing all the seacocks and through hulls on Stella. My reasons are: the original Groco SVs are nearing 30 years of age. They still work but Groco stopped making parts for them 20 years ago. They are not through-bolted that I can see; apparently they are held in place by the threaded couplings with the through hulls and a lot of 5200. A few of the wooden backing plates are deteriorating; I'd prefer fiberglass backers glassed to the hull. Finally, although I might get a couple more years out of them, the boat's on the hard and I can do the work now vs in 2 years when I haul her again. (as you can tell, I'm still trying to rationalize a large, time-consuming project.)

So with all that as preamble, I'm confident in my ability to install the new ones. Just wondering what I'm in for removing the old ones--especially detaching the old backing plates from the hull/sea chest and breaking the 5200 bond--if it is 5200. Anybody done this? I have a Fein Multimaster and thought I might be able to cut through the adhesive with that.

I just eliminated all through hulls below the waterline except one (for the engine). Our boat is a 1978 and I am confident they were all original. I was pleasantly surprised how easy they were to remove.

Google "3M 5200 Removal" and you will turn up several products that claim to work... can't speak for any as I haven't used them.
18" of wire or braided fishing line w/ dowel handles on each end are effective at cutting through the bond in tight areas. Also heat definitely helps - best w/ heat gun vs torch close to FG.

To remove 5200 use a heat gun if you have one (a hairdryer would work) and heat the whole area. Leave it on long enough to make sure everything warms up. Then take a sharpened putty knife and slice thru the caulk little by little. This has worked every time for me.
I have a Fein and never tried it on caulk. I'd be afraid I'd do damage.

I agree with the heat, putty knife and using the wire fishing line. I was amazed at how well the fishing line worked when other things didn't. The trick is you need somewhere to start, and that is where the putty knife has created a slot. Then work the fishing line back and forth and it cuts through it. Make sure to use the dowels or something like that because the line will cut thru your hand too. Good luck.

Just use a propane or mapp gas torch. Only takes a few seconds or so of heat to soften up the 5200.

Great ideas. I've used heat in the past to get 5200 off, but not the fishing line/wire trick. Thanks very much! Think I'll save the Fein for other jobs.

A little weight on it from inside while you are heating and using wire on the outside helps as well.

Adolescent children are perfect for this task.

You may get Lucky

Most older boats used a caulking for through hulls. Something like LifeCaulk. Heat softens most adhesives and caulk. I guess the next question is what about the hoses, There probably the same age as the through hulls. If the through hulls are in good shape currently, I don't think I would worry about the lack of replacement parts. I would likely replace hose clamps and hoses first. Hose clamps are the weak link with through hulls.

Several of mine would not unscrew even though broken fear of the hull....wound up grinding the outer mushroom head off and just pulled them through.

You will probably need special too A
If you look inside the mushroom head you can usually see tow protrusion. The tool fits in there so you can unscrew it.

SD

skipperdude said:

You will probably need special too A
If you look inside the mushroom head you can usually see tow protrusion. The tool fits in there so you can unscrew it.

SD

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Used a variety of tools including a through hull wrench that it is called where I come from....didn't matter.....

was planning on replacement anyhow..... so grinding was quicker than fooling around...bronze disappears fast to a 4" grinder.

skipperdude said:

You will probably need special too A
If you look inside the mushroom head you can usually see tow protrusion. The tool fits in there so you can unscrew it.

SD

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A chunk of flat bar and a Crescent wrench works too...

That's why I called it special tool A. I've used lots of things. What ever gets the job done. Tool B. Big hammer. Tool C .giant screw driver��

SD

All good advice above, you can also drve a dowel in the thruhull, slip a holesaw over it, and saw the flange off the thruhull which will release the whole thing. You are not going to reuse the thruhulls anyway.

One other thing, I replaced all the old seacocks on the Seeker with new Grocos only to find that they were all defective for which Groco took no responsibility other than replacing the parts after I hauled, removed, & sent the defective ones to them. I replaced them with Appolos and will never buy anything from Groco again (too bad, they have been around since clipper ships)

psneeld said:

Several of mine would not unscrew even though broken fear of the hull....wound up grinding the outer mushroom head off and just pulled them through.

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I've done the same. Very fast removal.

Scary said:

Most older boats used a caulking for through hulls. Something like LifeCaulk. Heat softens most adhesives and caulk. I guess the next question is what about the hoses, There probably the same age as the through hulls. If the through hulls are in good shape currently, I don't think I would worry about the lack of replacement parts. I would likely replace hose clamps and hoses first. Hose clamps are the weak link with through hulls.

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The hoses are relatively new but some of the clamps are old and perforated. A few are broken or deformed. I'll probably go with Awab below the waterline.

I called Groco and ended up talking to a guy who used to make the SVs. He was really helpful. Said they are built like tanks; you just have to make sure the rubber core isn't lumpy and that metal tube inside isn't crushed or corroded. So I now plan to disassemble them and see what kind of shape they're in before deciding whether to replace them.

Brooksie, I read about your experience on another site. Hate to hear that. It does sound like Groco got a bad batch of metal, but they should have stood behind their product better for you.

Brooksie said:

All good advice above, you can also drve a dowel in the thruhull, slip a holesaw over it, and saw the flange off the thruhull which will release the whole thing. You are not going to reuse the thruhulls anyway.



One other thing, I replaced all the old seacocks on the Seeker with new Grocos only to find that they were all defective for which Groco took no responsibility other than replacing the parts after I hauled, removed, & sent the defective ones to them. I replaced them with Appolos and will never buy anything from Groco again (too bad, they have been around since clipper ships)

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That is a GREAT idea. I am on the hard getting a bottom job done and am still trying to remove an "improper" seacock. Apparently the seacock (installed later than the build date) has NPT threads which were tightened "beyond needed" onto the NPS through hull threads. I actually took my Fein (what a tool) and notched twice into the SC with cuts perpendicular to the threads and still no help to get it loose. I'm gonna return this weekend with the "heavy artillery" and will hopefully get it loose. If not, I will go the dowel rod route. I'm still hoping to salvage the 2" through hull.


1983 Present 42 Sundeck
Twin Lehman 135's

So once you get it out what are you replacing them with? Metal or composite? Forespar makes some cool three way composite units and if used for engine intake works for fresh water flush and emergency bilge pump.

Sorry I don't understand why would you want to salvage that? Old thru hulls are a problem waiting to happen. Stray current corrosion can cause the metal to become spongie as the tin or is it the copper migrates out of the brass. Forget which is the most noble. I've seen old thru hill break off right at the hull under the seacock.

SD

eyschulman said:

So once you get it out what are you replacing them with? Metal or composite? Forespar makes some cool three way composite units and if used for engine intake works for fresh water flush and emergency bilge pump.

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I haven't thought that far ahead- just assumed I would go bronze. I'm gonna study up on the composite you are suggesting. I can see the advantages.


1983 Present 42 Sundeck
Twin Lehman 135's

eyschulman said:

So once you get it out what are you replacing them with? Metal or composite? Forespar makes some cool three way composite units and if used for engine intake works for fresh water flush and emergency bilge pump.

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Are you talking about a manifold seasick? With more than one water outlet?

Good point SD. I guess another $80 is not much for peace of mind. It's great to have you back.
I have a new acronym. BOAST. Break out at least several thousand!!!?


1983 Present 42 Sundeck
Twin Lehman 135's

I cans find the product mentioned on the Forespar site. The flanged Seacock (what I am going to install) only goes to 1.5" so not big enough.


1983 Present 42 Sundeck
Twin Lehman 135's

Heavy artillery. tool D large pipe wrench. My tools are all labeled. ��

skipperdude said:

Heavy artillery. tool D large pipe wrench. My tools are all labeled. ��

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Is that what we call a Stillson wrench?

Forkliftt said:

I cans find the product mentioned on the Forespar site. The flanged Seacock (what I am going to install) only goes to 1.5" so not big enough.


1983 Present 42 Sundeck
Twin Lehman 135's

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I saw one site with up to 1 1/2" and another site with 2" full flow ball valve units. I believe I have the 2"

skipperdude said:

Are you talking about a manifold seasick? With more than one water outlet?

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Yes my through hulls are three way depending on where handle goes like for over board head three way valves. The main channel goes to engine from the through hull the other channel is your choice bilge pump fresh water flush or most of the time inactive.

Angus is correct, The Groco SV series of seacocks were very well made. What causes them to be replaced is that the rubber plug swells into the water passage when the valve is closed. The rubber eventually hardens into a bump that makes it hard to turn the valve. Forcing it can cause the rubber to break loose from the shaft. The rubber bump can be sanded off but eventually the rubber fails to seal and the seacock must be replaced.

Skipperdude, the type of corrosion you're talking about is called dezincification. It only happens to high zinc brasses, not low zinc bronzes such as Groco and other name brand seacock manufactures use.

Bronzes are suceptable to electrolysis from stray currents, that is why you bond them to sacrificial zinc anodes.

Bronze seacocks are much stronger than the plastic ones. I wouldn't use the old Forespar Marlon seacocks. The newer design they sell to boat builders looks pretty good, if you want a plastic seacock. While Forespar doesn't market them to the aftermarket, they can be ordered.