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Huge improvement to my 4788! - Vent Fan replacement

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    Huge improvement to my 4788! - Vent Fan replacement

    This is a big one!

    After 8 years of having everyone on the dock know when I use the head, because of the jet turbine fan I have solved the problem!

    Here’s how I did it.

    I replaced the nasty little turbine fan with a Jabsco Flexmount blower p/n 35515-0010

    This is a squirrel cage design and MUCH quieter. Now it is about the same loudness as a bathroom fan in a dirt house!

    Bayliner did a REAL good job of hiding the OEM fan. You have to take the drawer in the pilothouse out, and the drawer frame as well. The drawer frame is just four screws that come in through the top, underneath the vinyl covered insert.

    You will have to replace or extend the 3” duct from the exhaust port, and mount the fan in an actual accessible location on the big plywood area behind the dash.

    I’m about 4 hours into the job, but most of it was figuring out how to do things.

    YIPPEE!!!

    Another problem area solved!

    KEVIN SANDERS
    4788 LISAS WAY - SEWARD ALASKA

    #2
    Thank you Kevin! I’ve got a similar fan I bought about a year ago but have not gotten around to doing it yet. You have done the legwork that will make it easier! I don’t recall exactly, but I remember looking at the schematic and wondering if the wiring will be adequate for the new fan. Did you check that aspect yet?
    Steve
    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
      Originally posted by Woodsea View Post
      Thank you Kevin! I’ve got a similar fan I bought about a year ago but have not gotten around to doing it yet. You have done the legwork that will make it easier! I don’t recall exactly, but I remember looking at the schematic and wondering if the wiring will be adequate for the new fan. Did you check that aspect yet?
      Steve
      The wire is #14 and the fan draws 4.8 amps. The breaker doesn't trip

      From the aft head you cannot even hear it.

      Forward head you can tell it’s on, but not loud.

      It really blows some air!

      BTW I stole your idea. I think you said you had a fan and had bench tested it, so I bought one.

      KEVIN SANDERS
      4788 LISAS WAY - SEWARD ALASKA

      Comment


        #4
        That’s hilarious! I won’t even turn the breaker on. If I do my wife will use the damn thing and it drives me nuts it’s so loud (and I am slightly hard of hearing!) Thank you! I’m going to install it... I really am....
        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


          #5
          Kevin - did you also access the fan are from below? Through the “attic” that’s above the master? I modified the ceiling panel so that I can remove it anytime I like and I use the space for paper goods. But I seem to recall seeing the fan arrangement although I never gave it much thought. I guess I should post the mod I did...
          Patti & Gordon Lewandowski
          Sammamish WA
          1998 4788 (April 2018)
          ”Knot Home”

          Comment


            #6
            The fan is literally jammed between the drawer frame and the hull, about the same level as the exhaust vent and about 12” aft.

            The only way a human can get to it is to remove the drawer frame, which is only four screws. Then you can reach it from the drawer opening

            There is no way to get to it from the “attic”, but I relocated the new fan to be in the attic, about a foot behind the drawer frame.

            In order to get the drawer frame out of the way you will need to to remove the vent hose from the master head. You can do this by dropping the vent fixture from inside the head then removing the vent hose.

            KEVIN SANDERS
            4788 LISAS WAY - SEWARD ALASKA

            Comment


              #7
              Originally posted by ksanders View Post
              The fan is literally jammed between the drawer frame and the hull, about the same level as the exhaust vent and about 12” aft.

              The only way a human can get to it is to remove the drawer frame, which is only four screws. Then you can reach it from the drawer opening

              There is no way to get to it from the “attic”, but I relocated the new fan to be in the attic, about a foot behind the drawer frame.

              In order to get the drawer frame out of the way you will need to to remove the vent hose from the master head. You can do this by dropping the vent fixture from inside the head then removing the vent hose.
              I just did this project myself, and I will echo part of Kevin's comments--in regards to the location, it plain old sucks! The stupidity of putting it between the drawer and the wall makes no sense when they could have easily extended the ducting a few feet and made it easy to access.

              However, I did NOT remove the drawer--I wanted to, but couldn't figure out how. I, a big guy, managed to wedge myseful up onto the plywood and was able to reach in there and cut out the fan and splitter. I then used duct tape to extend the ducts (go figure, actually using duct tape to tape ducts!!). I installed a new fan and just put it on top of the big plywood area (forward bathroom roof).

              Parts I used:
              https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
              https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

              Overall result is a HUGE IMPROVEMENT. Seriously, it was a huge pain to get this done, took way longer than I would have expected but it was worth it! We can now leave the fan on without driving everyone crazy which is huge for keeping humidity down after showering.

              My biggest tips:
              1. use a good ladder for access so you can easily climb in and out of the upper space.
              2. Leave the drawer out. You will do a combo of reaching through the bottom of its space and working from inside.
              3. You will fit. I'm a big guy, 275lbs, I managed to get in there, so can you.

              Took me about 3 hours. I didn't bother securing the fan as it can just sit there attached to the ducts, if I was being more thorough I might have--I did zip tie the ducts in a few places so it isn't really going anywhere.

              Edit: Total cost was about $40--~$20 each for the fan and ducting. (not counting the mistakenly purchased 4" fan)
              2000 Bayliner 4788 "Perfect Balance"
              370HP Cummins
              Zodiac YL 340 30HP Nissan
              Moored at Roche Harbor

              Comment


              • vinomaker
                vinomaker commented
                Editing a comment
                What fan did you buy for $20? The Jabsco Kevin listed is $78.

              #8
              Originally posted by jmoultray View Post


              However, I did NOT remove the drawer--I wanted to, but couldn't figure out how. I, a big guy, managed to wedge myseful up onto the plywood and was able to reach in there and cut out the fan and splitter.
              WOW! I go completely up in the “attic” a fair amount, but always with my head towards the port side (to service my pilothouse furnace). I tried and could not easially figure out how to get myself up, and facing starboard, and be able to get back out.

              You are the Yoga master!

              KEVIN SANDERS
              4788 LISAS WAY - SEWARD ALASKA

              Comment


                #9
                Originally posted by ksanders View Post

                WOW! I go completely up in the “attic” a fair amount, but always with my head towards the port side (to service my pilothouse furnace). I tried and could not easially figure out how to get myself up, and facing starboard, and be able to get back out.

                You are the Yoga master!
                I just bellied up and slid forward on my stomach... wasn't the most comfortable but unlike the engines it isn't greasy and other than a couple screws nothing sharp to cut myself on. Getting legs up and threw wasn't easy, and I was worried about putting too much weight on any one place/board so always was careful to spread the load out and not stand or kneel on the plywood around the opening. Doing it with a real ladder is key so you know you can get out!
                2000 Bayliner 4788 "Perfect Balance"
                370HP Cummins
                Zodiac YL 340 30HP Nissan
                Moored at Roche Harbor

                Comment


                  #10
                  Well..... Kevin motivated me and I did it yesterday! It’s definite boat yoga! It does help to remove drawer and drawer but most of the work is lying on your stomach in the attic. I mounted it on some heavy 1/2” thick rubber then screwed the rubber down. No direct hard connection to ceiling. I just reused the existing 3” flex duct. I had to use one 3” coupling that I scavenged. It would be nicer to just buy 20’ of the nice blue smooth duct. It would probably makes it quieter and increase air flow. Try to minimize elbows and make runs as straight as possible. Air restriction reduces air flow and makes more noise. The elbow in the pic is too abrupt. I will need to get a little more duct to smooth out the radius. The other runs are quite straight. I may install a 12v speed control to slow down the fan a bit. It’s still a little noisier than I would like but moving 3X more air so no problem reducing air flow a bit.
                  Last edited by Woodsea; 06-11-2019, 09:49 PM. Reason: Add
                  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
                    Originally posted by Woodsea View Post
                    Well..... Kevin motivated me and I did it yesterday! It’s definite boat yoga! It does help to remove drawer and drawer but most of the work is lying on your stomach in the attic. I mounted it on some heavy 1/2” thick rubber then screwed the rubber down. No direct hard connection to ceiling. I just reused the existing 3” flex duct. I had to use one 3” coupling that I scavenged. It would be nicer to just buy 20’ of the nice blue smooth duct. It would probably makes it quieter and increase air flow. Try to minimize elbows and make runs as straight as possible. Air restriction reduces air flow and makes more noise. The elbow in the pic is too abrupt. I will need to get a little more duct to smooth out the radius. The other runs are quite straight. I may install a 12v speed control to slow down the fan a bit. It’s still a little noisier than I would like but moving 3X more air so no problem reducing air flow a bit.
                    That’s pretty much exactly where I put my fan.

                    from the exhaust vent there was a about foot length of hose that I would have to un caulk, and remove the vent from the outside to access. I used my handy dandy vibrating saw to cut the old fan apart to make a coupler.

                    Good idea using the rubber under the fan! Next time up there I might do the same.

                    KEVIN SANDERS
                    4788 LISAS WAY - SEWARD ALASKA

                    Comment

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