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Identifying Trim Tab Cylinders

Discussion in 'Stabs, Tabs & Gyros' started by TahoeJohn, Oct 18, 2020.

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  1. TahoeJohn

    TahoeJohn Member

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    This is the best picture I have of the starboard trim tab on a 2001 Horizon 76.
    trim tab.jpg

    There is a bit of a leak in one of the cylinders (sheen on the water when active) so I'd like to replace the cylinders. The controls at the helm are Bennett, but when I sent this picture to Bennett, they stated that these cylinders were not from them.

    There's an OilDyne pump in the lazarette for each side:
    trim tab pump.jpg

    First, a stupid question: Why are there three cylinders?

    And is there a way to identify the manufacturer of the cylinders prior to haul-out? I'd like to get them ordered and ready to install by the yard.

    Thanks for any help or tips!
  2. Capt J

    Capt J Senior Member

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    The center one looks added because the other 2 weren't strong enough and from Bennett......The other two.......well.....welcome to the world of Taiwanese.......Taiwan tends to copy other people's parts with mixed success......I would just change the cylinders to Bennetts that you could retrofit, or the entire tab assemblies themselves......I don't see how the outboard ones and center one could work in harmony as the geometry is totally different......I would tend to recommending changing to a complete bennett trim tab assembly.
  3. mapism

    mapism Senior Member

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    I agree with everything CJ said, but I would fit Twin Disc rather than Bennett trim tabs.
    The latter are in fact more popular, because their low price stuff is installed on gazillions of small boats.
    But for a boat as large and heavy as a Horizon 76, not even the top of the line Bennetts can hold a candle to Twin Disc stuff.
  4. Capt Ralph

    Capt Ralph Senior Member

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    Look up the Parker-Oildyne web sites. Send them the pictures.

    That top picture alone would ensure me to re-explore this whole boat. What a Micky Mouse contraption.

    The depth of the photo makes it look like a short (fore to aft) tab, or is it really that short?
  5. d_meister

    d_meister Senior Member

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    The Bennett may have been added to provide angle sensor capability for a dash gauge. Is there a position indicator for the tabs?
  6. Capt Ralph

    Capt Ralph Senior Member

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    You may have a good point.
    However, tab position senders are available stand alone (no cylinder) also.
  7. Capt J

    Capt J Senior Member

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    Twin disc doesn't market trim tabs in the United States. I've never seen a set of trim tabs with Twin Disc name on them, ever. Bennett and then boat leveler...
  8. TahoeJohn

    TahoeJohn Member

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    This might explain a lot. Yes, there's a position indicating gauge at the helm... labeled Bennett. Tomorrow I'm going to see if I can confirm that the 3rd (middle) cylinder is merely a sensor.

    I think (not sure) that Twin Disc is involved only because they bought BCS Marine, but I'm not yet sure that these tab systems have anything to do with BCS. It's likely something Taiwanese, as you say.

    Thanks for all the good input so far from all. Very helpful already. Might just need to replace everything, as suggested.
  9. TahoeJohn

    TahoeJohn Member

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    On they survey, they are listed as 19.5" x 17". Thanks for the suggestions.
  10. mapism

    mapism Senior Member

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    I wasn't aware of that.
    Out of curiosity, I just had a look at their US website and trim tabs are indeed mentioned:
    http://www.twindisc.com/marine-products/trim-tabs/
    But if you say that they aren't available, I take your word for it.
  11. Capt Ralph

    Capt Ralph Senior Member

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    Then it was the depth of photo that made them look short.

    I would hate to think somebody just added a wired cylinder just for the tab position feedback.

    Found the listing and pictures.
    I understand a lil bit more now.
  12. mapism

    mapism Senior Member

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    Agreed.
    I would hate even more the idea that this mr.somebody could have done anything else on the boat... o_O
  13. d_meister

    d_meister Senior Member

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    There won't be much to see, except a wire through the hull. The sensors mount in a standard-type Bennett cylinder:
    https://bennetttrimtabs.com/product/autotrim-pro-sensor-kit/
    Someone else mentioned that Bennett's aren't able to do the job on such a vessel. I can't speak to that, but it would seem that using a Bennett control pad and angle feedback with other cylinders and pumps doing the actual heavy lifting is a good solution.
    If nothing else, the unknown marque cylinders can be refurbed by a proper hydraulic shop. To them, cylinders are all basic ingredients. They don't need a manual or parts catalog until they start dealing with pumps.
  14. TahoeJohn

    TahoeJohn Member

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    Thanks again for the help! Our boatyard identified them as Teleflex. Apparently they are out of business but Cable Marine is hoping to find a couple of new-old stock, as they did just a few weeks back. If that's the case, then I'll take the two existing to a hydraulic shop, as you suggest, to keep as spares.
  15. TahoeJohn

    TahoeJohn Member

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  16. mapism

    mapism Senior Member

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    From the webpage you linked: "Double acting brass cylinder"
    Brass?!? WTF were they thinking is the question that springs to mind.
    In your boots, I wouldn't waste one cent in rebuilding those things.