# Replacing Sea Cocks Through Hulls/ How to tell Size?



## brianontheroad (Jun 9, 2008)

There are some great posts on this forum already for Sea Cocks and Through Hulls -- but being a bit a newbie to this I have a few questions. I'm going to haul my boat out next weekend and replace my bronze sea cocks, they're completely frozen, totally corroded and in general scary looking  I need to go ahead and order them, the yard charges $35 a day for my boat to be there and I'm on a tight budget (aren't we all......) soooooo..... how do I determine what size they are in advance so I can order good replacements?

Any thoughts on brands or places to order them?? this Groco with a triangel flange looks good.....

Groco Bronze Seacocks Tri-Flange

I'll post pictures soon of the existing sea cocks in hopes that will give you guys some more to go on...

as per usual,

Thanks!


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## T34C (Sep 14, 2006)

I don't mean to sound rude, but I'd start by measuring them. If you can't get to them to get an accurate measurment you could measure the outside with a pair of calipers.


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## brianontheroad (Jun 9, 2008)

not rude at all....I was wondering how to measure them....I can't measure them from the outside, they're under water until I get the boat hauled, for the sea cocks can I just measure the tube coming out of it? Would the output be the same as the input?


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## JT1019 (Aug 14, 2006)

Personally I order everything I can from Defender. They will have whatever you are looking for and have the best prices. If you like Jamestown of West Marine just tell them the Defender price and they will match it.

I replaced all my seacocks last year with the Forespar Marelon and I love them. They might cost a little more but I thought they were easier to work with and won’t corrode. I’m also a massive fan of not having to ground them since they are not metal. 

As far as getting the old ones out? GOOD LUCK! I ended up using a drill, hack saw and dremel to destroy them. It took about an hour each to get the old ones out and clean up the mess but it was well worth the effort.


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## sailingdog (Mar 19, 2006)

Measure them with calipers.  The Grocos are good... You do need to get the matching through-hulls to use with those seacocks.

Sailnet sells the Perko seacocks with matching throughhulls *HERE*.










The Marelon ones are good if you have decent access and can properly maintain them... Forespar makes much the same as the above in a single package...


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## badsanta (Oct 16, 2006)

I am a big fan or the triangle flange. If you are replacing the thru hull also, cut them off. I used a sawzall and cut off the valve and then split the thru hull in half made it easy and fast. My thru hulls were fine, but I destroyed the seal when I attempted to remove the valve. You are right to replace both. As to not grounding because someone is using a plastic valve, The thru hull is bronze and in the water, do you not want to protect that also?? As to the size, the measurement is the inside diameters, a 1-1/2 thru hull should have a 1-1/2 hole through it and should be close to 2" on the outside. Can you remove a hose from the sea-****? it is normally the same size as the thru hull. If you buy to big you can drill out a larger hole, but harder to make it smaller.


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## stuffinbox (Oct 19, 2006)

You want the inner diameter right?
Often its cast into the seacock. If not what's the ID of the hose from the seacock? You only have to match that right, unless you are going to upgrade your internal plumbing too.

Unless your valves are in tip-top condition, now would be the time to replace those too. My yard recently replaced mine -- it looks like as they twisted off the old valve or twisted on the new one, they damaged the through hull caulking (water weeps in from under the backing plate and now I have to re-haul to fix it.)

Don Casey has a nice webpage on replacing seacocks at... 
umm... sailnet says I can't be trusted to posted links in my message. Let's see if this works: 
http : / / www . boatus . com / boattech / casey / 07 . htm

- Stu


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## brianontheroad (Jun 9, 2008)

what valves should I replace? Any other thoughts on things to work on while I have the boat out of the water? The bottom is recently painted and I'd like to not have her hauled again any time soon :-D

Thanks,
Brian


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## sailingdog (Mar 19, 2006)

Check the rudder, rudder stock, bearings, etc. Also check the prop, cutless bearing, etc... Those and the through hulls are most of what cause you to get hauled...


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## Maine Sail (Jan 6, 2003)

*Brian..*

You should really consider using the Groco flanged adapters as opposed to a solid seacock. Why? In ten years when they need work or replacement you won't need to haul the boat! Simply remove & replace the seacock/bronze ball valve and the rest of the assembly stays put!

Read this: Replacing Seacocks (LINK)

Ad This: Thru-hull & Seacock Primer (LINK)

Groco Flanged Adapter:


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## brianontheroad (Jun 9, 2008)

thanks I'll try to find those.....your step by step for the through hull replacement as awesome BTW


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## badsanta (Oct 16, 2006)

stuffinbox said:


> My yard recently replaced mine -- it looks like as they twisted off the old valve or twisted on the new one, they damaged the through hull caulking (water weeps in from under the backing plate and now I have to re-haul to fix it.)
> - Stu


If the yard did that I would hope they fix it, or at the least give you a free haul. Some times you are smarter than people working there. They dont learn the right way as from this site. I dont know how many times I hear "we always do it like that"


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## badsanta (Oct 16, 2006)

Depending on your boat, you may need a backing board.


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## donradclife (May 19, 2007)

Labor saving tip for removing thru-hulls. Take a 4" grinder and grind off the outside flange, then knock the remnants into the hull. Takes less than 5 minutes per thru-hull. Especially effective if the old thru-hulls were bedded in 5200, as the heat from the grinding loosens the 5200.


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## brianontheroad (Jun 9, 2008)

nice tip don.....I'll try that, anyone know who has the best cost on Grocos/Perkos these days?


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## brianontheroad (Jun 9, 2008)

can someone look over what I've picked out?

Can you check these Groco's that I've picked out and let me know if they're the right things?

These for the valves for use with the adapter:

GROCO FULL FLOW IN LINE BALL VALVES - Valves & Seacocks by Discount Marine Supplies

This is the adapter

Bronze Flange Adapter

only problem is I've only found 1.5" adapters

Are these seacocks sturdy enough? I have 6! eeek....throughulls/sea cocks that ALL need to be replaced and for some I was thinking of using these

Groco Bronze Seacocks Tri-Flange

or would I be best served just getting the perko all in one package?


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## sailingdog (Mar 19, 2006)

Get these:



> These for the valves for use with the adapter:
> 
> GROCO FULL FLOW IN LINE BALL VALVES - Valves & Seacocks by Discount Marine Supplies
> 
> ...


Don't forget to get the through-hulls.... which I don't see you listing.


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## xort (Aug 4, 2006)

Maine Sail said:


> You should really consider using the Groco flanged adapters as opposed to a solid seacock. Why? In ten years when they need work or replacement you won't need to haul the boat! Simply remove & replace the seacock/bronze ball valve and the rest of the assembly stays put!


Maine

How do you replace the seacock while in the water? Stuff a plug in the thru-hull from below?


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## sailingdog (Mar 19, 2006)

A plug or put a toilet plunger over the through-hull. 


xort said:


> Maine
> 
> How do you replace the seacock while in the water? Stuff a plug in the thru-hull from below?


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## brianontheroad (Jun 9, 2008)

I'm leaning towards the perko's because I can't seem to find the flange adapters in any size other 1 & 1/2 inches Maine where did you buy them and did they have different sizes? My google searches haven't turned up much


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## Maine Sail (Jan 6, 2003)

xort said:


> Maine
> 
> How do you replace the seacock while in the water? Stuff a plug in the thru-hull from below?


Yep! Or pull the valve and quickly stick a plug in the flange then tape and pipe dope it then pull the plug and thread fast..

It's really not much harder than cleaning a speed log..


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## Maine Sail (Jan 6, 2003)

brianontheroad said:


> I'm leaning towards the perko's because I can't seem to find the flange adapters in any size other 1 & 1/2 inches Maine where did you buy them and did they have different sizes? My google searches haven't turned up much


Hamilton Marine about 2/3 of the way down this page (FLANGED ADAPTERS LINK). They don't have a photo but if you read the description they have all the sizes from .75 to 3"


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## xort (Aug 4, 2006)

Looks like I'll need to study up on replacing seacocks. Looks more of a salmon color than pink to me.


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## xort (Aug 4, 2006)

Maine
I did not find a step wrench at Hamiliton. I did find two at Jamestown distrib. Both said they were NOT for thru-hull removal, only for installing new thru hulls.
I have Grocos that need replacing.


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## Maine Sail (Jan 6, 2003)

*They ..*

They are generally used for installation but if the PO had used something other than 5200/4200, like a polysulfide, a step wrench can sometimes work. Generally when they are put in with 5200 it's hard not to destroy them or break the dogs off trying a step wrench.

If you have flanged seacocks you will need to use debond or heat to break the thru-hull free which still may not work. If it doesn't work you need to remove the through bolts and spin the seacock off the thru-hull. Once the seacock is off the thru hull a pipe wrench will break it free from the inside..


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## xort (Aug 4, 2006)

no flange

Groco tech support said to use some heat to loosen the caulk. have to be careful with that!


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## xort (Aug 4, 2006)

still fighting with 2 thru-hulls.
The dogs did break off the inside.
I cannot unscrew the valve because it is under a floor structure and won't go upward. VERY tight space. I need to unscrew the thru-hull downward outside and then slide the seacock out. Grinding the mushroom off will leave the threaded pipe part inside the hull stopping the removal of the valve.
PB blaster is soaking in there right now. I did get a very slight movement before the dogs broke off. I did use heat on the mushroom to break the bond.
So now what? Will a pipe wrench grab the mushroom?
Halp!


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