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Bedding a gas tank, experience, opinions and correct way.-gctid464670

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    Bedding a gas tank, experience, opinions and correct way.-gctid464670

    I have been contemplating the best way to install / bed a gas tank. I have two tanks each about 6' x1 1/2' tanks 106 gal. each. They both sit on a fiberglassed 3/4" plywood bunk with a box like bottom.

    The original bedding was 2 rubber strips on the bottom of the tank between the bunk and the tank and 2 stainless straps. Some crevis corrosion was occurring with the old system.

    I understand this is not the best practice and I have been wanting to install in a better way. The 2 systems I have read about are

    #1 glue bedding strips on the bottom of tank with 5200 and then glue tank to the bunk at the strips with 5200.

    #2. Bed the tank with foam. I'm not real excited about that method though but will if that's best.

    Next question what would you coat the tanks with if any thing?

    I'm thinking allumaprep and then paint with zinc chromate. Some say epoxy coal tar paint. I don't know about that.

    I got to thinking after reading the thread on the 32' the guy made a $17000 offer on and the comments made about 32 tanks.

    My tanks have very minor pitting now but I don't want it to get worse.

    What say ye?
    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

    #2
    I wonder how bedliner spray would do? It sticks, its tough.

    Doug
    Started boating 1955
    Number of boats owned 32
    Bayliners
    2655
    2755
    2850
    3870 presently owned
    Favorite boat. Toss up. 46' Chris Craft, 3870 Bayliner

    Comment


      #3
      dmcb wrote:
      I wonder how bedliner spray would do? It sticks, its tough.

      Doug
      I don't know but that stuff is really heavy.

      I am really looking for the best way to secure the tanks.
      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

      Comment


        #4
        My tank is V shaped on the bottom and when I put it in 2 years ago I did method #1 with the rubber strips running towards the center and the 5200.

        I did nothing to the tank with regards to a protective coating. I figured if Bayliner could put one in the way they did and it lasted for over 25 years, I should be OK. BTW my tank wasn't leaking when I replaced it but it did have pitting so I didn't want to chance it.

        Comment


          #5
          The tanks you were referring to on the 3270 and 3288 represent a common occurence due to a design defect. On the 32, water tends to accumulate under the tanks with no efficient path of exit. So much of the water that accumulates under the tanks tends to stay there. I helped a dock neighbor several years ago remove the port tank by cutting it into pieces. After the tank came out, I looked at the area under it...and had one of those WTF was Bayliner thinking moments!

          I removed and replaced the tank during my repower. Like Wayne's, my tank is V-shaped. Bayliner glassed four 2"X2" pieces of wood perpendicular to the tank. There were two pieces on the outer ends and two pieces supporting the middle. They used injected foam to fill the space, glued a 1/8 inch layer of plywood over it to make a smooth surface, and glassed over it. The tank sat on top of the glassed plywood with only a few foam strips coming between the tank and the surface it sat on. Bad, bad, bad, bad Bayliner! The tank sat there for 35 years, no pitting whatsoever, and lasted that long. However, the plywood was brittle and removable with a putty knife, the foam was soaked with water, the 2"X2" perpendicular pieces were rotted.

          Here was my solution. I glassed 3"X3" pieces perpendicular pieces and cut them to the shape of the deadrise. I glassed a piece of plywood so that I have a flat surface. My previous tank was V-shaped. My new tank is a cube with a flat bottom. I placed the tank directly on the surface and used the factory provided mounting brackets to secure it. Now there is plenty of room for water to move freely in and out of the area under the tank. It always drains into the bilge and is evacuated by the bilge pumps. I keep my bilge dry to begin with, so I need not worry about water staying there and rotting it. But whatever water goes in comes back out now.

          If my tank was aluminum or stainless steel, I would use the rubber strips to seat it. However, I would take measures to prevent water from getting into there. Perhaps a bead of 5200 around the perimeter of the tank that makes contact with the surface. If the tank is sitting against a bulkhead, it would be difficult to get around it, but the bead could terminate at the bulkhead perhaps?

          Comment


            #6
            Rubber strips, foam, and bare wood are the 3 worst items for contact with the fuel tank.

            Have the new fuel tank epoxy coated, that is what they use on the there end boats.

            Use plastic strips, here are the instructions.

            http://www.yachtsurvey.com/fueltank.htm
            Pat says: DO-IT-RIGHT THE FIRST TIME!

            Bayliner 3870 "ALASKA33)
            Twin 350 GM power
            Located in Seward, AK
            Retired marine surveyor

            Comment


              #7
              Boatwork is correct, foam and wood hold moisture against the metal, and rubber is downright acidic.

              Use strips of plastic, or consider buying some of that silicone fuel/vacuum line popular with the import tuners that is available in all sorts of bling bling colors. Do a few wraps around the tank and drop it in. I've done this in a couple of other applications and really liked the "cushion" it provided against the brackets chaffing the tank.

              Comment


                #8
                Steve D'Antonio had an article about this a while ago. Key points:

                Unless a tank is designed and built to be self-supporting (this would include internal reinforcement), all tanks ideally should rest on continuous, shelf-like structures, rather than on stringers or beams of some sort. When supported in this manner, flexing is minimized, if not eliminated. In order to promote drainage and prevent corrosion to a metallic tank's bottom, 1- to 2-inch-wide, ┬╝-inch-thick strips of non-hygroscopic material (prefabricated fiberglass or GPO-3 works well) should be bedded athwartships to the tank bottom, on 4- to 6-inch centers, using a polyurethane bedding compound. With this approach, the tank can't rest in standing water and water can't migrate between the tank and the shim spacers, both of which would lead to corrosion.

                Link:

                http://www.passagemaker.com/subscrip...ponent&print=1

                Comment


                  #9
                  So I called every plastic supplier in the spokane area and not one of them even knew what hay site was.

                  Does anyone have an idea where I can find some?
                  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

                  Comment


                    #10
                    The same material that cutting boards are made of is available in 4' x 8' sheets, they are usually cut on site to your dimensions.

                    Polyethylene sheets or a similar product, you only need a piece thick enough to allow air to circulate under the tank, 5200 under and 5200 on top of the strips.

                    If using banding to secure the tank use clear tubing over the banding, if using wood bracing use plastic between the tank and the bracing and in any contact area same as the bottom.
                    Pat says: DO-IT-RIGHT THE FIRST TIME!

                    Bayliner 3870 "ALASKA33)
                    Twin 350 GM power
                    Located in Seward, AK
                    Retired marine surveyor

                    Comment


                      #11
                      boatworkfl wrote:
                      The same material that cutting boards are made of is available in 4' x 8' sheets, they are usually cut on site to your dimensions.

                      Polyethylene sheets or a similar product, you only need a piece thick enough to allow air to circulate under the tank, 5200 under and 5200 on top of the strips.

                      If using banding to secure the tank use clear tubing over the banding, if using wood bracing use plastic between the tank and the bracing and in any contact area same as the bottom.
                      Yeah, any plastic shop will have the HDPE sheet he needs.

                      Keep in mind 5200 does NOT stick well to HDPE, and HDPE expands and contracts very differently than aluminum. This isn't a big deal because a mechanical connection between the tank and the HDPE is not required. However, this does mean having a decent layer of 5200 on the tank is useful, since when they separate, water will get sucked into the void... so you want enough polyurethane to prevent it from touching the tank.

                      Comment


                        #12
                        Would Sikaflex polyurethane be a better choice for an adhesive?
                        Pat says: DO-IT-RIGHT THE FIRST TIME!

                        Bayliner 3870 "ALASKA33)
                        Twin 350 GM power
                        Located in Seward, AK
                        Retired marine surveyor

                        Comment


                          #13
                          "Bedding a gas tank"

                          First... calling her a "gas tank" probably isn't the most romantic thing to do. Also the term "bedding" hasn't been used for that purpose since medieval times me thinks (see what I did there?)

                          And further..... why are you asking for such personal advice on an open forum?..... oh wait..... you mean...... Ohhh I see..


                          Aquatic Muse
                          Mount Vernon, WA
                          MMSI: 367498870
                          '79 Bayliner Santiago w/ Mercruiser 470 power and drive

                          Comment


                            #14
                            Mileskb wrote:
                            "Bedding a gas tank"First... calling her a "gas tank" probably isn't the most romantic thing to do. Also the term "bedding" hasn't been used for that purpose since medieval times me thinks (see what I did there?)And further..... why are you asking for such personal advice on an open forum?..... oh wait..... you mean...... Ohhh I see..
                            The bed!!!! Sorry its all dusty and dirty from fiberglass dust. If you look at it its in the aft most corner of the bilge on both sides. If water gets on top of the bunk there is no way for it to escape only evaporate. The outer side of the bunk is sitting on the outterer most chine and cannot be drilled for drainage.

                            http://baylinerownersclub.org/media/....jpg[/img]
                            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

                            Comment


                              #15
                              I think a polyurethane adhesive would be more flexible and won't hold moisture like 5200 will.

                              Comment

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