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Forward Compartment Leak

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  • Forward Compartment Leak

    Gentlemen of the Jury, I'd like to get some community advice if you'd all be so kind. Last night I was doing some function testing / ballasting of my boat with a newly configured 2" SD. There were a few instances where I got it to submerge and then surface, but also a few where (for various reasons) it ended up at about a 45-50 degree up angle in the water, hanging by its nose in about 3ft of water. After a half dozen or so tests, I noticed there was some water accumulation in the forward and aft compartments. Enough to cause a batt-link monitor to stop blinking. C'est la vie on that one, I suppose.

    I had the seals greased with a petroleum jelly, which I've now read may not have been the best thing to use - although that was based on a comment in an earlier thread about lubricating servo pushrods. I also noticed there was a nick out of my front end-cap, that could very well be the cause of a pinhole leak. See the attached photo. No idea how it got there, honestly.

    Click image for larger version

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    After drying everything out, I buttoned-up the aft end, plugged the necessary induction/pump lines, and blew into the open front end of the WTC with it's ass submerged in a bowl of water. Not so much as a bubble. So I'm guessing the leak is coming from up front? I spoke to Bob, who was gracious enough to send a replacement end cap with some other components I've ordered. Of course, my plan is to halt all wet testing until then and use that once it arrives.

    My question then, is about leak checking the forward compartment, and how to proceed with testing without getting the insides wet again. Any advice is appreciated. Thanks!


    -Brady

  • #2
    That 'nick' is a casting void/flaw. If it does not extend to the o-ring grove, it is of no consequence.

    David
    "... well, that takes care of Jorgenson's theory!"

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    • #3
      Yes, the void is on the dry side so shouldn't cause any problems. fill it with epoxy or thick superglue if it bothers you.

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      • #4
        The casting flaw actually does continue through to the o-ring channel. In fact itís almost as deep as the o-ring itself. I closed everything up last night and attempted a leak check. The only thing that seemed to happen was the front cap began to dislodge from the change in pressure inside the dry space.

        What I donít understand is how it got water ingress the other night when it was in the pool. Perhaps the cap doesnít fit snugly enough and the repeated suction/equalization from the SAS system caused it to wiggle forward enough to let in a bit of water?
        Last edited by DMTNT; 09-05-2018, 01:04 PM.

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        • #5
          SAS is either in a state of vaccum or ambient pressure, not pressure increase. If anything, the ballast system would suck the caps tighter against the tube body.

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          • #6
            You can get a small pressure increase when pushing the cap home, then with the motors running and heating the air, that can further pressurize the internal space. Admittedly the pressure rise will be very small, and water temperature will have an impact on this too, but it could be enough to move the cap a bit. Equalize the pressure inside the wtc with the schrader valve once sealed.
            DIVE IN! Go on, go on, go on, go on, GO ON! http://www.diveintomodelsubmarines.co.uk

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            • #7
              Originally posted by Subculture View Post
              You can get a small pressure increase when pushing the cap home, then with the motors running and heating the air, that can further pressurize the internal space. Admittedly the pressure rise will be very small, and water temperature will have an impact on this too, but it could be enough to move the cap a bit. Equalize the pressure inside the wtc with the schrader valve once sealed.
              That's a really good point. Whoever thought of that must be pretty damn smart *cough*

              You guys are an invaluable resource. Thank you all for the continued advice!

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