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Thread: Seacock Substitute?

  1. #1
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    Default Seacock Substitute?

    I want to get a thru-hull low in the skinny part of my bilge. The 1 1/2" Marelon seacock is 5" thread to thread and with an outlet connection it would force me to bring the thing so high up that it might suck air when heeled, and certainly would in a seaway. (mackinaw boat, it is really skinny aft and not very deep) An industrial gate valve in 1 1/2" NPT bronze is only 2 13/16 front-to-back. Is this a bad idea and/or would an inspector get neurotic over this option? The valve is rated 200 psi @ 406 degrees. I might eventually want to do "6-pack" charters with this boat but will have no gasoline or diesel aboard. The photo below is from Grainger, stock number 5JLV9. Grainger is not saying what kind of Bronze this is....

    Please advise,
    Ken

    5JLV3_AS01.jpg

  2. #2
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    Default Re: Seacock Substitute?

    IMHO, that is not a viable solution. I suspect that your Coast Guard will not allow it on a six-pack boat, either. The idea of a seacock is that the valve body is an integral part of the mount to the hull, thereby not having any fittings (nipples, thru-hulls, etc.) between the valve and the hull that could fail. What is the seacock for, so deep in the hull?
    Hope for the best, but plan for the worst.

  3. #3
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    Default Re: Seacock Substitute?

    A marine surveyor would call out the gate valve as a no- no, but I don't know what effect that might have on a six-pack, since it is literally an operator of an uninspected vessel license (OUPV).

    A seacock is servicable; has a grease fitting for maintenance, and one can tell at a glance whether it is opened or closed. All components are corrosion-proof, though that may be less critical in freshwater use.

    Let me ask what is the issue--the length or the ability to swing the handle? If you are concerned with it sucking air, just close the valve underway unless its needed ( best practice anyway).

    Another seacock advantage is the ability to rig remote levers to open and close them.

    Screen Shot 2018-08-30 at 11.21.40 AM.jpg

    You can also reach down with a socket wrench to extend reach. The hole in the handle is intentionally 3/8-inch square for that reason.

    Screen Shot 2018-08-30 at 11.23.41 AM.jpg

    Remote operation is not possible with a gate valve.

    Just some thoughts.

    Kevin
    There are two kinds of boaters: those who have run aground, and those who lie about it.

  4. #4
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    Default Re: Seacock Substitute?

    Quote Originally Posted by Breakaway View Post
    A marine surveyor would call out the gate valve as a no- no, but I don't know what effect that might have on a six-pack, since it is literally an operator of an uninspected vessel license (OUPV).

    A seacock is servicable; has a grease fitting for maintenance, and one can tell at a glance whether it is opened or closed. All components are corrosion-proof, though that may be less critical in freshwater use.

    Let me ask what is the issue--the length or the ability to swing the handle? If you are concerned with it sucking air, just close the valve underway unless its needed ( best practice anyway).

    Kevin
    The issue is that if I would put the seacock perpendicular to the inside of the hull the area is so narrow that I have to move it vertically up to a very much wider section of the hull, therefore much closer to the waterline. I want to use this thru-hull a combined Port Starboard cockpit drain, so it wants to be as low as possible and it wants to develop some suction under-way. I also want to use the aperture with additional valves as an inlet to fill ballast tanks. The Marelon seacock I already bought has no grease fittings but it says grease once a year, I am not sure how one does that.

    Ken

  5. #5
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    Default Re: Seacock Substitute?

    Groco make the seacock shown below that has a 1-1/4" side outlet for auxiliary purposes. You may be able to fit a threaded tee to the main inlet to run your cockpit drains into. The price is a bit eye-watering, though.

    Hope for the best, but plan for the worst.

  6. #6
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    Default Re: Seacock Substitute?

    The Coast Guard does not inspect 6-pack boats other than basic required safety gear, navigation lights etc required on any vessel of a given size. Insurance for a 6-pack boat is another issue though. Insurance companies would require a survey.

  7. #7
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    Default Re: Seacock Substitute?

    There's another problem with gate valves. The gate is raised and lowered by a threaded rod that screws into the gate. The rod is held in place so that when it turns, the gate rides up and down on the threads. If those threads rot out (and they do rot out) the gate will stay right where it is, no matter how many times you turn the handle it won't close.

    Don't use a gate valve!
    Schooner captains love to get blown offshore!

  8. #8
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    Default Re: Seacock Substitute?

    Heed the advice of those who know!
    Having said that, I have fitted gate valves in tight fitting non-marine applications by unscrewing the mechanism from the body, screwing the body on, and then reinstalling the rest of the valve once the body was in place.
    There is nothing quite as permanent as a good temporary repair.

  9. #9
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    Default Re: Seacock Substitute?

    Quote Originally Posted by mmd View Post
    IMHO, that is not a viable solution. I suspect that your Coast Guard will not allow it on a six-pack boat, either. The idea of a seacock is that the valve body is an integral part of the mount to the hull, thereby not having any fittings (nipples, thru-hulls, etc.) between the valve and the hull that could fail. What is the seacock for, so deep in the hull?
    That's interesting. I have a couple of seacocks, in fact maybe almost all my seacocks, where there is a through hull, then an elbow, then the seacock. And that might be a solution in the OPs situation. No problem getting an insurance survey, for what that's worth.

  10. #10
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    Default Re: Seacock Substitute?

    What can I say, Phil? There are thousands of boats with fittings that are less than optimal that have not had any problems... yet. Maybe they never will. Maybe they will. Maybe tomorrow. Insurance surveys are only as good as the person inspecting the boat, and beyond that, such surveys vary from country to country. Personally, I would not have a boat with fittings between the seacocks and the hull, and would not specify such an arrangement on any of my design work. But my word is far from being law.
    Hope for the best, but plan for the worst.

  11. #11
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    Default Re: Seacock Substitute?

    At least use a high quality ball valve. There is no reason to use a gate valve.

  12. #12
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    Default Re: Seacock Substitute?

    Marelon makes some right-angle seacocks.
    https://www.fisheriessupply.com/fore...-hose-barb-oem

  13. #13
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    Default Re: Seacock Substitute?

    Quote Originally Posted by mmd View Post
    What can I say, Phil? There are thousands of boats with fittings that are less than optimal that have not had any problems... yet. Maybe they never will. Maybe they will. Maybe tomorrow. Insurance surveys are only as good as the person inspecting the boat, and beyond that, such surveys vary from country to country. Personally, I would not have a boat with fittings between the seacocks and the hull, and would not specify such an arrangement on any of my design work. But my word is far from being law.
    Your word may not be the law, but the law says the same, if my memory is correct. Plumbers' gate valves are a decided no-no on through-hull fittings because they sink ships for the reasons set forth above, as well as because the face of the gate itself is rather thin and subject to corroding through, leaving one with no valve at all. You're also correct that "There are thousands of boats with fittings that are less than optimal that have not had any problems... yet."

    A properly plumbed cockpit drain system is dependent only upon the height of the cockpit sole above the waterline. Placing the through-hull drain deeper in the bilge isn't going to make a whit of difference because the water level in the drain line is always going to be level with the waterline when the cock is open. "Sucking air when heeled" is of no moment, but the proper arrangement is to install two through-hulls, port and starboard, with the drain lines from the port and starboard cockpit drains crossed so that the starboard drain discharges through the port through-hull and vice versa. If your cockpit sole is a bit too close to the waterline, you may get your toes a bit wet (which can be avoided with a grating on top of the sole,) but that should be no matter. Think this one out and you should be able to solve the problem without resorting to putting a hole in the bottom of your boat that you may not be able to close.

  14. #14
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    Default Re: Seacock Substitute?

    Quote Originally Posted by mmd View Post
    But my word is far from being law.
    And here I thought it came from a burning bush...
    Heute ist so ein schöne Tag...

  15. #15
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    Default Re: Seacock Substitute?

    The only time my voice comes from a burning bush is when I am doing the annual trimming of the hedge by the lane, and even then, it's not law...



    (...not my hedge, but the same plants... - mmd)
    Hope for the best, but plan for the worst.

  16. #16
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    Default

    Maybe not law but I have no doubt you are right. Not about to change what I have but it confirms my dim view of the value of insurance surveys.


    Sent from my iPhone using Tapatalk

  17. #17
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    Default

    PS. I would not be happy with a gate valve.


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  18. #18
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    Default Re: Seacock Substitute?

    Having just replaced a 6 year old gate valve in my house that would not turn - I'd have to agree with a no on using one in a boat. I'm happy to use a 50 year old W-C seacock as long as it laps smooth though.
    "If it ain't broke, you're not trying." - Red Green

  19. #19
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    Default Re: Seacock Substitute?

    Quote Originally Posted by mmd View Post
    The only time my voice comes from a burning bush is when I am doing the annual trimming of the hedge by the lane, and even then, it's not law...
    That may very well be. But if the topic is boats, and you're speaking, I'm just going to go ahead and pretend you're reading off of stone tablets you brought down from Blueberry Barren. I just figure it's safer that way.
    Heute ist so ein schöne Tag...

  20. #20
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    Default Re: Seacock Substitute?

    Having just replaced a 6 year old gate valve in my house that would not turn - I'd have to agree with a no on using one in a boat. I'm happy to use a 50 year old W-C seacock as long as it laps smooth though.
    I had to change a shower faucet valve this AM. I discovered the hot water gate valve in the basement ( No idea of its age--at least 16 years since I bought this house and I have never changed it) worked almost 100-percent: It wouldn't shut off completely and allowed a trickle of water to still flow.

    I changed the faucet valve washer then went back to the hardware and replaced the gate valve. Would suck to find my boat sunk at the slip because of a trickle.

    Kevin
    There are two kinds of boaters: those who have run aground, and those who lie about it.

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