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Adding Drop Fins to my Trim Tabs ...from another thread-gctid810469

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    Adding Drop Fins to my Trim Tabs ...from another thread-gctid810469

    After engaging the other current thread on trim tabs, I've decided to add drop fins to my Boat Levelers. While I could make them longer than the 9" chord, if I get even Ôàô more lift from the drop fins, I'm not sure I really need more length.

    I just picked up 4 pieces of 12ga stainless plate from my local scrap dealer, ....$30! I I also picked up two dozen ┬╝" x 1" SS bolts and locknuts, so I will be bolting them to the existing tabs.



    To even out the stress on the piston, I'm doing a Ôàô-Ôàö, 4" and 8". I'm also angling ┬¢" of the inner fin so the angular flow from the dead rise will go under the tab rather than over it and create spray.



    Now I'm off to do some metal cutting .....in my wood shop. Fun, fun, fun. B)
    "B on D C", is a 1989 2459 Trophy Offshore HT, OMC 5.7L, Cobra OD, Yamaha 15hp kicker. Lots of toys! I'm no mechanic, just a blue water sailer and woodworker who loves deep sea fishing.
    MMSI: 367637220
    HAM: KE7TTR
    TDI tech diver
    BoD Puget Sound Anglers North Olympic Peninsula Chapter
    Kevin

    #2
    Sounds interesting Crunchie . . keep us appraised of your progress with pictures, please. One thing that I noticed while looking at a video of mine - the drop fins seem to "not be in line with the water coming out from under the boat" . . . . don't know if that makes sense to you but it almost seems as if the whole tab and the drop fins are "angled" a bit off the center line . . . probably just an optical illusion but my opinion anyway.
    1998 Avanti 3685 - "Dad's Dream" w 454 Mercs - for sale - Dredge Harbor, NJ
    Former - "Home Aweigh" 2003 - 2452 Bayliner Cierra Classic Hardtop Cruiser
    WQQM835 MMSI: 338147209
    James H. Stradling

    Comment


      #3
      "Dadrock33" post=810490 wrote:
      Sounds interesting Crunchie . . keep us appraised of your progress with pictures, please. One thing that I noticed while looking at a video of mine - the drop fins seem to "not be in line with the water coming out from under the boat" . . . . don't know if that makes sense to you but it almost seems as if the whole tab and the drop fins are "angled" a bit off the center line . . . probably just an optical illusion but my opinion anyway.
      I thought the same thing, but that doesn't make sense to me. FWIU, the drop fins 'catch' the water climbing the dead rise, and that would create lift. To angle them with the flow would lose that, and to angle them against that would create more drag than lift.
      "B on D C", is a 1989 2459 Trophy Offshore HT, OMC 5.7L, Cobra OD, Yamaha 15hp kicker. Lots of toys! I'm no mechanic, just a blue water sailer and woodworker who loves deep sea fishing.
      MMSI: 367637220
      HAM: KE7TTR
      TDI tech diver
      BoD Puget Sound Anglers North Olympic Peninsula Chapter
      Kevin

      Comment


        #4
        Got 'em cut to size and marked for bending. Thought it would be more difficult to cut, but my little 4.5" angle grinder with a thin cutting blade, followed by a sanding wheel make quick work of it.



        Tomorrow I'll take them over to get them bent.
        "B on D C", is a 1989 2459 Trophy Offshore HT, OMC 5.7L, Cobra OD, Yamaha 15hp kicker. Lots of toys! I'm no mechanic, just a blue water sailer and woodworker who loves deep sea fishing.
        MMSI: 367637220
        HAM: KE7TTR
        TDI tech diver
        BoD Puget Sound Anglers North Olympic Peninsula Chapter
        Kevin

        Comment


          #5
          Get the holes punched into them if you can. Stainless steel is no fun to drill.

          Comment


            #6
            "pjumper" post=810506 wrote:
            Get the holes punched into them if you can. Stainless steel is no fun to drill.
            Not a problem. I have lots of ┬╝" titanium and cobalt bits, my drill press slowest speed is 400rpm, and I have about a pint of cutting oil. I also have a diamond wheel bit sharpener.

            I even have the polishing wheel and compounds to give them a really nice mirror finish shine .....if I suddenly get that much needed rush of enthusiasm to do that, .... :whistle:
            "B on D C", is a 1989 2459 Trophy Offshore HT, OMC 5.7L, Cobra OD, Yamaha 15hp kicker. Lots of toys! I'm no mechanic, just a blue water sailer and woodworker who loves deep sea fishing.
            MMSI: 367637220
            HAM: KE7TTR
            TDI tech diver
            BoD Puget Sound Anglers North Olympic Peninsula Chapter
            Kevin

            Comment


              #7
              Sounds like you have it covered. Let us know how the tabs work out

              Comment


                #8
                Crunchie, you can sharpen drill bits?? I'll send my 5 gallon bucket of used ones over pronto. :lol:
                Dave
                Edmonds, WA
                "THE FIX"
                '93 2556
                Carbureted 383 Vortec-Bravo II 2.0:1 18 1/4x19 P

                The rebuild of my 2556 https://www.baylinerownersclub.org/f...76?view=thread
                Misc. projects thread
                https://www.baylinerownersclub.org/f...56-gctid789773

                Comment


                  #9
                  "builderdude" post=810517 wrote:
                  Crunchie, you can sharpen drill bits?? I'll send my 5 gallon bucket of used ones over pronto. :lol:
                  LMAO! Yeah, but results say I rarely do. I buy more than I sharpen, and I mostly sharpen the bigger ones and the expensive ones. I picked up ahttp://www.grizzly.com/products/Prof...ctor sharpener from Grizzly Tools awhile back. Works good, though it took a LOT of practice.
                  "B on D C", is a 1989 2459 Trophy Offshore HT, OMC 5.7L, Cobra OD, Yamaha 15hp kicker. Lots of toys! I'm no mechanic, just a blue water sailer and woodworker who loves deep sea fishing.
                  MMSI: 367637220
                  HAM: KE7TTR
                  TDI tech diver
                  BoD Puget Sound Anglers North Olympic Peninsula Chapter
                  Kevin

                  Comment


                    #10
                    the objective of drop down fins is to capture the water flow under the tab rather than allowing it to blow out the sides. by maintaining this captured water flow you increase the lift. the fins need to be on the outer edges of each tab to be most effective.


                    Attached files

                    Sea Venture
                    2000 3055, 5.7/B2, 18x23" props
                    Cruising the PNW and beyond.
                    DIYC, Riverhouse Marina
                    MMSI 316029971

                    Kirk
                    Drinks well with others.

                    Comment


                      #11
                      "SprinterX" post=810535 wrote:
                      the objective of drop down fins is to capture the water flow under the tab rather than allowing it to blow out the sides. by maintaining this captured water flow you increase the lift. the fins need to be on the outer edges of each tab to be most effective.
                      All due respect, I disagree. http://www.baylinerownersclub.org/in...s sense to me, so I'm going to try it. It's just bolts and some stainless steel and I can always change it.
                      "B on D C", is a 1989 2459 Trophy Offshore HT, OMC 5.7L, Cobra OD, Yamaha 15hp kicker. Lots of toys! I'm no mechanic, just a blue water sailer and woodworker who loves deep sea fishing.
                      MMSI: 367637220
                      HAM: KE7TTR
                      TDI tech diver
                      BoD Puget Sound Anglers North Olympic Peninsula Chapter
                      Kevin

                      Comment


                        #12
                        Next step completed, they are bent!



                        My friend couldn't do them, because his brake takes up to 16ga. After visiting 4 other shops, I found a sheet metal company who had a brake that was older then both of us put together. Total cost: $18!

                        I stopped by the boat to mark where the holes need to go, and discovered the piston mount has pan-head bolts, and they need to be drilled through the drop fins too. I also need longer bolts ...which I have.

                        I also discovered the current tabs have an 8" chord; I thought they were 9".

                        Now I'm off to drill some holes. Yeehaw!
                        "B on D C", is a 1989 2459 Trophy Offshore HT, OMC 5.7L, Cobra OD, Yamaha 15hp kicker. Lots of toys! I'm no mechanic, just a blue water sailer and woodworker who loves deep sea fishing.
                        MMSI: 367637220
                        HAM: KE7TTR
                        TDI tech diver
                        BoD Puget Sound Anglers North Olympic Peninsula Chapter
                        Kevin

                        Comment


                          #13
                          Drilled and buffed.



                          Next is put holes in the tabs. I'll be drilling them in place, so I'm sure my arms and back will need a hot tub after. The tabs are on there so securely, I'd rather not disturb them.
                          "B on D C", is a 1989 2459 Trophy Offshore HT, OMC 5.7L, Cobra OD, Yamaha 15hp kicker. Lots of toys! I'm no mechanic, just a blue water sailer and woodworker who loves deep sea fishing.
                          MMSI: 367637220
                          HAM: KE7TTR
                          TDI tech diver
                          BoD Puget Sound Anglers North Olympic Peninsula Chapter
                          Kevin

                          Comment


                            #14
                            Crunchie, looks good, you gonna angle the leading edge of the drop fin a bit?
                            Dave
                            Edmonds, WA
                            "THE FIX"
                            '93 2556
                            Carbureted 383 Vortec-Bravo II 2.0:1 18 1/4x19 P

                            The rebuild of my 2556 https://www.baylinerownersclub.org/f...76?view=thread
                            Misc. projects thread
                            https://www.baylinerownersclub.org/f...56-gctid789773

                            Comment


                              #15
                              hope you are using 316 ss. or they will rust.
                              1993 43.88 bayliner motoryatch

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