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Viking Trim Tabs

Discussion in 'Viking Yacht' started by def94403, Jul 27, 2010.

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  1. def94403, Jul 27, 2010
    #1
    def94403

    def94403 New Member

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    I am the new owner of a 35 ft sportfisher with twin CATs. I am having trouble getting the factory trim tabs to bring the bow down. Some people are trying to get me to add, 36x9 in bennet trim tabs. I just find it hard to believe Viking installed such ineffective tabs. At 2000 rpm I am doing 17 knots and putting out a huge tail. The tail starts to shrink at around 2300 rpm and I can get 21 knots. Any information would be helpful.
  2. Mark I, Jul 28, 2010
    #2
    Mark I

    Mark I Member

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    Are you sure they are actually going up and down?
  3. NYCAP123, Jul 28, 2010
    #3
    NYCAP123

    NYCAP123 Senior Member

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    I believe I caught on another thread earlier that the viking is a 1987. Boats from the 80's tended to be heavy and sometimes have trouble getting up on plane. I assume that 2300 is WOT? As Mark suggested check to make sure that the resevoir has fluid and that the tabs are actually working. Also, any growth on the bottom or props won't help. For more help you may have to go for the bigger tabs though. Another thing that might help in the mean time is to bring her up to WOT to get her on plane and then back off to cruise speed. Another thing that might help is more weight forward. Is that where your water tank is? Filling that might help.
  4. def94403, Jul 28, 2010
    #4
    def94403

    def94403 New Member

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    Thanks for the help guys. Yes I'm sure they are going up and down. I have actually reached over the swim platform and checked it. As far as the total travel that I can't answer. In terms of the weight I'm sure that's a factor as it seems worse as I filled the diesel tank with 120 gallons. Again thanks for the input.
  5. Capt J, Jul 29, 2010
    #5
    Capt J

    Capt J Senior Member

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    Those Vikings tended to run very stern heavy. If you cannot install a larger tab. I have had Aluminum blocks made that went between the ram and the tab and allowed the tab to be lowered an additional 1.5", the only downside is in the all of the way up position it didn't sit flush with the hull....it stuck down an inch to 1.5". But on this particular boat it made a drastic change.
  6. Mark I, Jul 29, 2010
    #6
    Mark I

    Mark I Member

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    I never would have thought of this before, but someone on another forum had a non retracted tab break while backing down and it folded over into his prop. This was on a 30 something egg of a newer vintage and I have no idea if the tabs were fully extended but I would consider any implications of not being able to retract the tab all the way.
  7. def94403, Oct 14, 2010
    #7
    def94403

    def94403 New Member

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    Fixed my trim tab problem

    So we pulled the boat out. Turns out the trim tabs were 30"x8 and the edge was flush to the transom. We welded on a 30x12" plate , what a difference the additional 4" make past the transom. At the same time we found out that the props were missed matched 22x24. Previous owner must have damaged one and found a deal about a 1/4" difference in diameter. So I traded up to a 4 blade michigan 22x22 and OMG. The Viking is a beast now, we figured we picked up 15% in efficiency. Happy ending
  8. ScrumpyVixen, Oct 15, 2010
    #8
    ScrumpyVixen

    ScrumpyVixen Member

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    Good to hear you solved it and transformed the performance.

    I am guessing the out of pockets included:

    • Pulling it out;
    • Work to put the new plates on;
    • New prop(s)

    Got to love it, otherwise.........
  9. def94403, Oct 16, 2010
    #9
    def94403

    def94403 New Member

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    plus while it was out bottom paint, basically a 5k week on the boat... yea gotta love it.