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    4788 490 Leak Fix Thread

    This would be a good time for us to document the leaks we have found on our 4788’s and 490’s

    If you could indicate what the symptom was, and what the eventual fix was, that would help future owners

    I’ll start

    ___________________________________

    SYMPTOM

    Water visible on the valence in the aft part of the salon and water driping from aft salon light fixtures

    FIX

    This was all traced to the radar arch interface with the flying bridge roof.
    After attempting to seal up the Radar Arch I solved the leak by pouring 1/2 gallon of boat resin into each of the sides of the radar arch at the inspection ports, and then re-driling new weep holes in the radar arch above the resin line.

    ____________________________________

    SYMPTOM

    Wet carpet in the master stateroom on both sides. This included wet carpet at the edge of the foreward head.

    FIX

    This was fixed by re-bedding the rail bases. Upon removal of the valance(s) the leaking was apparant as the rail base bolts were rusty and there was evidence of long term water seepage. I used new bolts 1/4” X 4” and nylock nuts with washers as the original bolts appear to be either metric or a odd ball thread pitch. The rail base in the foreward head was the easiest right above the porthole. Upon re-assembly I declined to re-install the port hole cover which resulted in a large shelf just below the porthole being usable

    _____________________________________

    SYMPTOM

    Wet bunk stateroom and mid stateroom mattrresses

    FIX

    This was traced to the rail base above the upper bunk stateroom berth. Removing the large panels above the berth exposed the rail bases where seepage was evident. Water had also been running aft into the mid stateroom.

    _____________________________________

    KEVIN SANDERS
    4788 LISAS WAY - SEWARD ALASKA

    #2
    We are a few days into our journey north and have had a bit of rough water. With the bow cutting through the waves, the bow wave is impacting the port lights and rub rail pretty hard. Water is leaking where the ceiling joins the wall above the port lights. I am wondering if water hitting the port lights hard enough could squirt the water somehow behind the frame. It does not seek to be leaking through the rubber seal. Could this be the port lights or am I facing a leaking rub rail?
    2000 4788 w Cummins 370's, underhulls, swim step hull extension
    12' Rendova center console with 40HP Yamaha
    MV Kia Orana
    Currently Alameda CA

    Comment


      #3
      Well here’s my quick solution to try and isolate. Also found caulk missing under the rub rail under the bow sprit. So dug out a two foot strip and replaced with 4000 quick dry.
      2000 4788 w Cummins 370's, underhulls, swim step hull extension
      12' Rendova center console with 40HP Yamaha
      MV Kia Orana
      Currently Alameda CA

      Comment


        #4
        Well... That sure is a interesting look. Just a bit Arkansas I think...

        I’m interested in what you find. I have an issue where in rough seas I get water ingress seeping onto the carpet starboard side, almost like it’s coming out from under the head compartment. Doesn’t happen in torrential rain, just when we run in rough seas.

        I’m suspecting a lower side rub rail leak.

        KEVIN SANDERS
        4788 LISAS WAY - SEWARD ALASKA

        Comment


          #5
          I’ve found there can be a tremendous amount of water pressure pushing against those portholes. Unless they are tightened down really hard, water can seep in.
          "Impasse". 2001 3988
          Cummins 330's
          Puget Sound

          "You don't want to be the richest guy in the nursing home..."

          Comment


            #6
            Originally posted by ksanders View Post
            Well... That sure is a interesting look. Just a bit Arkansas I think...

            I’m interested in what you find. I have an issue where in rough seas I get water ingress seeping onto the carpet starboard side, almost like it’s coming out from under the head compartment. Doesn’t happen in torrential rain, just when we run in rough seas.

            I’m suspecting a lower side rub rail leak.
            Kevin, we have experienced a similar leak in our 490 in rough weather. In rough seas we get a wet spot just outside the master head door (not right next to the door, but a few inches out and an inch or two away from the step for the berth). We haven't done much in the way of troubleshooting this yet, as it doesn't seem particularly serious and we have only experienced it twice.

            However, it is something I want to address.
            GMS
            2008 Meridian 490
            2010 ArrowCat Express 30 (sold)

            Comment


              #7
              Originally posted by GMS View Post

              Kevin, we have experienced a similar leak in our 490 in rough weather. In rough seas we get a wet spot just outside the master head door (not right next to the door, but a few inches out and an inch or two away from the step for the berth). We haven't done much in the way of troubleshooting this yet, as it doesn't seem particularly serious and we have only experienced it twice.

              However, it is something I want to address.
              Yep, pretty much the same leak.

              KEVIN SANDERS
              4788 LISAS WAY - SEWARD ALASKA

              Comment


                #8
                Originally posted by bal734 View Post
                I’ve found there can be a tremendous amount of water pressure pushing against those portholes. Unless they are tightened down really hard, water can seep in.
                I've got a rough-seas leak in my forward porthole on the starboard side. I'm fairly positive it is water coming in around the gasket of the window in the porthole. I've tried cleaning the gasket and using liberal amounts fo Superlube without much success. I know some here have had success in replacing the gasket material but I haven't yet tried this. For now, leaving towel on the shelf below the window does the job to keep the interior and the mattress dry.
                Evan
                2001 Bayliner 4788 "Fifty / Fifty II"
                League City, TX

                Comment


                  #9
                  FWIW, each of the storage hatches next to the bow seat have drains. These drain on the “bin”is connected to the drain hole on the outside of the deck side by a small tube. If this tube comes loose water in the storage hatch drains into or behind the lockers and results in a wet spot on the carpet (in front of the master head if on the starboard side). The guys detailing our boat figured it out when I noted water coming in to the fwd stateroom. Probably not the cause here unless the rough water splashing up on deck is coming into the storage hatch because the hatch isn’t battened down. Removing the hatch and bin and reconnecting and or replacing the hose is on my winter project list.
                  Patti & Gordon Lewandowski
                  Sammamish WA
                  1998 4788 (April 2018)
                  ”Knot Home”

                  Comment


                    #10
                    Here’s what we have discovered so far:
                    The chisel point of the latches actually contacts the plexiglass first and pushes the glass out of the frame. This was part of the leak. We trimmed off the end of the chisel and rebed did the plexiglass with marine silicone. It’s not leaking here now.
                    The gasket seal does not appear to leak.
                    The water appears to leak behind the frame where it seals to the hull. I retaped this with aluminum tape for the next leg. I suspect it will only last an hour but that should be long enough to determine if that is the culprit.

                    i experienced the deck locker leaking into the closet. The bottom of the locker is just some gel coated plywood. I fiberglassed this up and redrilled the drain. No problem since
                    2000 4788 w Cummins 370's, underhulls, swim step hull extension
                    12' Rendova center console with 40HP Yamaha
                    MV Kia Orana
                    Currently Alameda CA

                    Comment


                      #11
                      Guys- I’m probably crazy but where everyone finds water is exactly where the shower sump leak collects. It only happens in heavy seas, not heavy rains. Is there any chance water in rough seas could be flowing back thru the shower sump drain hose from the thru-hull and overwhelming the sump?
                      Drew Haas
                      1998 4788 "Painkiller"

                      Comment


                        #12
                        I had a similar leak a few seasons back. I noticed significant wet carpet in front of our port side master suite closet after a rather rough water crossing.

                        After getting back to the dock
                        I closed up everything and sprayed all over the bow with a hose while the wife watched from inside. It was coming in around the outer edge of the port light frame, leaking down the inside wall of the closet and soaking the carpet all the way into the bunk stateroom carpet.
                        In my case it was the portlight frame caulking had dried out. I had to pull the portlights and rebed with fresh caulk. A bit of work but solved the issue for us.
                        4788 PH 2001, Cummins 370's
                        2355 C Express, 1996 5L
                        17ft Cobra, 1985, 125HP

                        Exploring the Salish Sea

                        Comment


                          #13
                          Hi All
                          If you have the metal Rub Rail I would highly recommend a bead of caulk on upper and lower sides,because you can't believe how much of a gap their is between the Deck and Haul joint their is if you haven't repaired/ replaced the Rub/Rail the gap can be from 0 to 1/4 in.and Bow and transom corners even greater.I used 3 tubes of 3M5200 to seal it when I installed our new Rub/Rail.
                          Also as said earlier caulking the port lights is a good idea......Good luck....Brad
                          Brad & Sharon
                          Lady Jake
                          1985 4550 EH 700TI /Twin Disc 502
                          LaConner,Wa. (summer)
                          2003 Scout CC 24' W/225 Yamaha
                          kailua Kona,Hi (Winter)

                          Comment


                            #14
                            [QUOTE=Knot_Happy;n452016 I had to pull the portlights and rebed with fresh caulk. A bit of work but solved the issue for us.[/QUOTE]

                            Can you let me know how the porthole is attached? Mine has carriage bolts that don't go through so they must attach to the outer frame. One is loose and just pulls out- doesn't look stripped so I'm reluctant to unscrew the others in case there are loose nuts on the inside. I've traced my leak to the port porthole and it looks like the caulking needs replacing.

                            1988- 3288, 1994- 3288, now 2001- 3788

                            Comment


                              #15
                              Thanks for everyone’s responses! Here’s some more info:
                              Drew Hass, I don’t think the shower sump is the problem in my case. I’ve modified that area so that if/when the sump overflows, it drains into the bilge.
                              Knot Happy, I think this is where at least a portion of our leaking is coming from. I used aluminum tape to seal the frame to hull joint and now, with milder sea conditions only one porthole is leaking. How did you go about removing port lights?
                              Brad4550, I am thinking there may be some rub rail leaking as well. I have caulked upper and lower rub rails and it appears to be intact. Any chance it could be coming in from the screws that hold the rubrail to the boat?
                              2000 4788 w Cummins 370's, underhulls, swim step hull extension
                              12' Rendova center console with 40HP Yamaha
                              MV Kia Orana
                              Currently Alameda CA

                              Comment

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