Spacer for factory trim tab?

Discussion in 'Bennett Trim Tabs Vendor Forum' started by Mittens, Nov 8, 2018.

  1. Mittens

    Mittens Active Member

    589
    Mar 5, 2017
    Huntsville, AL
    2002 340 Sundancer, All Cherry Cabin, Black Canvas.
    8.1 Mercs, V Drives, 4.5kw Westerbeke.
    In another thread it was suggested to add a 1" spacer to the mounting bracket to give the factory tabs more angle...

    would this over tax the rams?

    my boat in question is a 2002 340 Sundancer. I plan to pull boat for bottom paint this winter and plan to install drop fins, and possibly a spacer or larger tabs....

    I want to shove the bow down and get back on top of the water.
     
  2. PlayDate

    PlayDate Well-Known Member

    Dec 25, 2006
    Washington DC
    1994 370 Express Cruiser
    454 Mercruisers
    I would be concerned about the pressure you would be placing on the bottom hull hinge and tab by increasing the angle beyond its current lower limit.

    [​IMG]
     
  3. Tabman

    Tabman Member

    700
    Jan 11, 2007
    The Tab Cave
    boatless
    boatless
    Two things to be concerned with.

    You may indeed be pushing the interlocking hinge too far down and damage it or bend the Tab itself.

    The standard angle of deflection for the Tabs provides the best lift to drag ratio. If you deflect it more than that it will create more drag than the addition lift it can generate. In other words it will stop being a Trim Tab and become a brake.

    Tom McGow
    Bennett Marine
     
  4. Mittens

    Mittens Active Member

    589
    Mar 5, 2017
    Huntsville, AL
    2002 340 Sundancer, All Cherry Cabin, Black Canvas.
    8.1 Mercs, V Drives, 4.5kw Westerbeke.
    which hing you worried about the upper or the lower on the Ram?
     
  5. juggernaut1

    juggernaut1 Active Member

    871
    Apr 19, 2015
    Perth, Western Australia
    2006 38 Sundancer
    8.1S / ZF 63V Drives
    I think his concern is the tab to hull backing plate hinge, rather than the actuator hinges.
     
  6. Tabman

    Tabman Member

    700
    Jan 11, 2007
    The Tab Cave
    boatless
    boatless
    Yes, the hinge on the transom! On most of our Tabs it's an interlocking hinge. It's very strong and corrosion resistant, but unlike a piano hinge it cannot go all the way down or up.

    Tom
    Bennett Marine
     
  7. techmitch

    techmitch Well-Known Member SILVER Sponsor

    May 1, 2008
    Chesapeake Bay, Middle River/Frog Mortar Creek MD.
    1999 270 DA
    Twin 4.3s W/Alpa I Gen II's
    I would have to think that a spacer would also affect maneuverability when backing into a slip or backing down in general, not to mention excess stress on the rams when doing so. Tom?
     
  8. Mittens

    Mittens Active Member

    589
    Mar 5, 2017
    Huntsville, AL
    2002 340 Sundancer, All Cherry Cabin, Black Canvas.
    8.1 Mercs, V Drives, 4.5kw Westerbeke.
    but could it go a little farther with some spacing or is this a big no no? some detail from the forum vendor would be great.
     
  9. Tabman

    Tabman Member

    700
    Jan 11, 2007
    The Tab Cave
    boatless
    boatless
    You can a little bit, but you will reach the point of diminishing returns very quickly! Not sure what you mean by "some detail from the forum vendor would be great".

    Tom McGow
    Bennett Marine
     
  10. Mittens

    Mittens Active Member

    589
    Mar 5, 2017
    Huntsville, AL
    2002 340 Sundancer, All Cherry Cabin, Black Canvas.
    8.1 Mercs, V Drives, 4.5kw Westerbeke.
    SO extensions are basily a bad idea.

    drop fins on stock tabs or use same mounting and angles, but a larger tab
     
  11. Tabman

    Tabman Member

    700
    Jan 11, 2007
    The Tab Cave
    boatless
    boatless
    I have seen extensions work fine, some examples here on Club SeaRay. But since I work for Bennett and we don't make or test them I cannot recommend them or give guidance about them.

    Drop Fins do help and adding larger Tabs do too.

    Do you have a photo of the transom and Tabs you could post?

    Tom
    Bennett Marine
     
  12. Mittens

    Mittens Active Member

    589
    Mar 5, 2017
    Huntsville, AL
    2002 340 Sundancer, All Cherry Cabin, Black Canvas.
    8.1 Mercs, V Drives, 4.5kw Westerbeke.
    I do, will post it when I leave work today (On a classified site with no phone at the moment.)
     
  13. MonacoMike

    MonacoMike Well-Known Member PLATINUM Sponsor

    Sep 15, 2009
    Indiana lakes and Lake Michigan
    2000 Cruisers 3870
    8.2 Mercs
    85 Sea Ray Monaco 197
    260hp Alpha 1
    Tom is the Bennett expert, so you are getting "detail from the forum vendor".

    Good luck,

    MM
     
  14. Mittens

    Mittens Active Member

    589
    Mar 5, 2017
    Huntsville, AL
    2002 340 Sundancer, All Cherry Cabin, Black Canvas.
    8.1 Mercs, V Drives, 4.5kw Westerbeke.
    Pic of my transom
     

    Attached Files:

  15. LG111

    LG111 Active Member

    560
    Jan 4, 2015
    NW
    410
    8.1
    I assume you are trying to get the bow down more? If not already, change the anchor line to chain.
     
  16. Tabman

    Tabman Member

    700
    Jan 11, 2007
    The Tab Cave
    boatless
    boatless
    Since there are no Drop Fins on the Tabs, I would a a set of DF12s to them first.

    Tom
    Bennett Marine
     
  17. Mittens

    Mittens Active Member

    589
    Mar 5, 2017
    Huntsville, AL
    2002 340 Sundancer, All Cherry Cabin, Black Canvas.
    8.1 Mercs, V Drives, 4.5kw Westerbeke.
    I have 250 foot of all chain now. Did that swap last year..

    This year new bottom paint, and while out tabs... so fins for sure. Got that. But should I make them bigger to? Wider to the tunnels? And then add drop fins? Or longer too. I don’t plan to pull it again so would rather have to much tab and can back off then not enough.

    And side note these pics where taken when I bought it. I don’t run around like a station wagon with those tops or is it named that or is it that dirty anymore.
     
  18. Tabman

    Tabman Member

    700
    Jan 11, 2007
    The Tab Cave
    boatless
    boatless
    Measure how much wider to the tunnels you can go and we can see what replacement tabs you could use. As I mentioned I cannot really help with larger Tabs fore to aft. Also you will need to reposition the actuators so that they are in the middle of the tabs side to side.

    Tom
    Bennett Marine
     
  19. Mittens

    Mittens Active Member

    589
    Mar 5, 2017
    Huntsville, AL
    2002 340 Sundancer, All Cherry Cabin, Black Canvas.
    8.1 Mercs, V Drives, 4.5kw Westerbeke.
    From the pics it looks like I could
    Go a French inches on each side. The outside would not follow the bottom exactly at the edge but seems it would still have water hitting it. So maybe 18inch wide with some drop fins would
    Bolt up and add a good amount?. I can measure from tunnel to tab.. wish I would have done that this summer. Would 3 inches in each side be noticeable? Then add the drop fins too?
     
  20. juggernaut1

    juggernaut1 Active Member

    871
    Apr 19, 2015
    Perth, Western Australia
    2006 38 Sundancer
    8.1S / ZF 63V Drives
    Around 20 months ago I added 1 inch to each side (to 26 inches) to max the available space and 3.5 inches to the chord (to 15.5 inches) as well as 3 inch drop fins. Actuators are fine, but I did sheer a nylon hinge pin during testing which I was able to change in the water. I replaced the pin with the stainless version and has been good ever since. Suggest you replace the hinge and pin fixtures to ensure reliability.

    I can now plane down to 12 knots with the tabs fully dug in whereas the tabs previously had no effect whatsoever at that speed. As I bury the tabs at that speed I also pick up around 3 knots, so I'm pulling back on the throttles to maintain the 12 knots which is the speed limit in one of the areas I boat.
     

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