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Any Problems/Danger/Reason mounting AC thru hull at water line ?-gctid418146

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    Any Problems/Danger/Reason mounting AC thru hull at water line ?-gctid418146

    I am thinking about drilling a new AC water outlet thruhull just at water level or maybe slightly below to put an end to water noise. Any draw backs to this that I cannot see?
    Cheers, Hans
    2007 Carver 41 CMY
    Twin Volvo D6-370
    Montreal, Canada
    Midnight Sun I Photos

    #2
    Well. if nothing goes wrong, no problem. But if Murphy pays your boat a visit and a hose clamp comes loose, it could potentially sink your boat.

    Kind of like an exploding Honda generator stored in the engine compartment.
    2007 Discovery 246
    300mpi BIII
    Welcome island Lake Superior

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      #3
      You'll install a seacock, yes? If so, there's no problem at all. It's just a cost decision made by the builder. Many newer and most upper-tier boats do this.

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        #4
        From a design point of view... is the water gravity feeding down? If so, being underwater can make it harder to get the condensate out of the hoses. For safety reasons I would install it slightly above the max load waterline myself. One less way to sink the boat.

        Yo wanna make that list smaller... not longer whenever possible.
        Custom CNC Design And Dash Panels

        iBoatNW

        1980 CHB Europa 42 Trawler- "Honey Badger"

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          #5
          This should be installed correctly and if so there shouldn't be a problem.

          Make sure its a metal underwater type through hull. It must have a seacock shut off valve on it that is screwed on to the through hull fitting. The through hull should use a back up plate and be sealed with 4200 or 5200.

          If you do that you should have no problems. I would however think there must be a better way to do that it might have sifficulty draining
          1989 Avanti 3450 Sunbridge
          twin 454's
          MV Mar-Y-Sol
          1979 Bayliner Conquest 3150 hardtop ocean express.
          Twin chevy 350's inboard
          Ben- Jamin
          spokane Washington

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            #6
            When you think about it this is just an intake through hull in the bottom of the boat to an exit thru hull in the side of the boat through which water circulates via a pump on demand by the AC. When not being used, water just sits there. At no given time is there maybe a few PSI at best. The exit would be located on the side of the boat just below my existing one however about 12" lower, either at or an inch above the water line. Correct me if I am wrong but a Seacock is just there in case of emergency or if you need to work on the hose while in the water, correct?
            Cheers, Hans
            2007 Carver 41 CMY
            Twin Volvo D6-370
            Montreal, Canada
            Midnight Sun I Photos

            Comment


              #7
              My raw water through hull outlet is installed about 12" above the waterline towards the bow, never had noise problems. The circulation pump is rated 600GPH and I get a steady stream coming out that makes almost no sound when re-entering the lake surface. If you are having trickling noise issues, perhaps there is simply not enough flow for a solid stream of water that should be ejected out and not make as much noise.

              For the entire AC installation I used 3/4 ID marine non collapsible reinforced wall hose. The through hull for the outlet has smaller ID than a hose for the circulation system so it forces the flow to come out more or less like from a low pressure fountain that is aimed downwards due to a hull dead rise. All I can hear when AC is running is the blower fan and the air rushing out of the vents. Also the circulation pump came in a kit with a raw water strainer, after using the included strainer the pump would occasionally cavitate and make noise. When I temporarily removed the strainer and let the circulation pump run with out it, the flow rate nearly doubled. After that I bough an after marked strainer for the intake almost 2x the size of the original that did not impede the flow.

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                #8
                Let me put this into perspective. My wife has to have the port-light open in the aft cabin when we go to sleep. The AC exit is about 4' forward of this so at night when things are dead quiet the noise although not loud can be annoying. During the day I would not even think about it.
                Cheers, Hans
                2007 Carver 41 CMY
                Twin Volvo D6-370
                Montreal, Canada
                Midnight Sun I Photos

                Comment


                  #9
                  Hans, as you know, the seacock is a safety measure. I wouldn't hesitate to add a through hull below the water if I needed it, but I'd also insist on doing it correctly, and that means having a seacock. For the very rare event that you ever need it. Your insurance company surveyor will prefer it too.

                  The through hull hole needs to oversized slightly and edge-sealed with epoxy, and the fittings installed with any quality adhesive sealant for below-water installations.

                  You do need to ensure it is just below water level. Those pumps are designed for circulating and aren't meant to operate against a significant static discharge head. If you put it say 2' below the waterline, you won't get sufficient flow. An inch or 2 underwater will be ok.

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