Can i make these trim tabs bigger?

Discussion in 'Bennett Trim Tabs Vendor Forum' started by Siboatguy, Jan 21, 2018.

  1. Siboatguy

    Siboatguy Active Member GOLD Sponsor

    232
    Mar 28, 2016
    Holmdel,NJ
    2005 Sea Ray 320 Sundancer
    Twins V-Drives
    2017 5.7 Mercruisers
    Is there anyway i can make my tabs bigger from (bow to stern)? And will that help?? I have a sea ray 320 props are redone. This year im gonna add 4 blades... I notice i always run bow high and gotta run at 3900 to stay on plane with out the ass sitting down... Was thinking of just welding a piece of stainless steel sheet metal on the bottom of it and turning the sides down?? If i change the trim tab and make it longer i was worried the piston won't be long enough... tabs1.jpg tabs2.jpg
     
  2. Gofirstclass

    Gofirstclass Well-Known Member GOLD Sponsor

    Apr 20, 2010
    Tri Cities, WA
    1995 550 Sedan Bridge,
    2010 Boston Whaler 130 Super Sport,
    1981 Boston Whaler 130 Sport,
    CAT 3406C's, 580hp.
    I had my trim tabs enlarged both front-to-back and side-to-side. I also had a hull extension made to increase the running surface of the hull but that was not done for increased lift.

    So, the simple answer to your question is "yes you can" enlarge the tabs.

    [​IMG]
     
  3. FootballFan

    FootballFan Well-Known Member

    Jun 20, 2012
    Florida
    Marquis 59
    MTU Series 60
    There is a guru of Tabs that is on several forums.

    Tabman

    I would see if you could get his input. Have seen him on here and some other forums. He helped me with some tab reconfiguration work last fall. He knows his stuff.

    Mark
     
  4. Siboatguy

    Siboatguy Active Member GOLD Sponsor

    232
    Mar 28, 2016
    Holmdel,NJ
    2005 Sea Ray 320 Sundancer
    Twins V-Drives
    2017 5.7 Mercruisers
    I'm hoping i hear from him tabman.... I would love to hear his input on it... Thanks again everyone for all the help....

    If i do add to it... curious if i should turn down the sides and if so how much and how much to add on... How much can the pistons handle...
     
  5. juggernaut1

    juggernaut1 Active Member

    812
    Apr 19, 2015
    Perth, Western Australia
    2006 38 Sundancer
    8.1S / ZF 63V Drives
  6. Tabman

    Tabman Member

    697
    Jan 11, 2007
    The Tab Cave
    boatless
    boatless
    While I seen successful instances of adding chord (fore to aft) to tabs by adding an extension to them, I can't "officially" recommend it. While the actuators are very strong, they can be damaged by the additional leverage. Particularly when backing down, as water "piles up" on top of the tab. This is exacerbated when there is a platform on the transom that forces even more water down when in reverse. 12" chord Tabs are the maximum we recommend.

    The addition of 3" drop fins is a good idea.

    Also I don't recommend welding as it invites corrosion.

    One idea would be to add Tabs over the prop tunnels and simply tee them into the existing actuators on either side.

    I hope this helps,

    Tom McGow
    Bennett Marine
     
  7. Siboatguy

    Siboatguy Active Member GOLD Sponsor

    232
    Mar 28, 2016
    Holmdel,NJ
    2005 Sea Ray 320 Sundancer
    Twins V-Drives
    2017 5.7 Mercruisers
    Thanks so much for looking into this tom (Tabman) The tabs over the prop tunnels don't know if i wanna get into that much work this year... Lets say i leave them that size maybe only go 3inchs longer but mostly add the drop fins.. Do you see a big difference from just drop fins? Ill just bolt on to the org trim tab.. unless i should buy a hole new tab?
     
  8. Tabman

    Tabman Member

    697
    Jan 11, 2007
    The Tab Cave
    boatless
    boatless
    They help quite a bit. The Bennett part number for them is DF12 https://www.defender.com/product.jsp?path=-1|2331321|2331349|2331353&id=2393734

    Tom
    Bennett Marine
     
  9. frosh coach

    frosh coach Member

    158
    Apr 20, 2011
    Long Island Sound, New Haven CT
    1994 300 Sundancer
    1989 230 Cuddy (SOLD)
    Twin Mercruiser 350 FWC, Alpha 1 Gen II
    I had 1/8" stainless plates made that I drilled and bolted to my existing tabs. The plates were about 4” wider, and 2” larger fore to aft. I also added the 3” drop downs as tab man suggested. This helped. I have a 30’ with twin i/o’s and a generator. There’s a lot of weight in the back end. I still run around 3500 though. The big difference is getting on plane when I’m loaded up.
     
  10. BillK2632

    BillK2632 Well-Known Member SILVER Sponsor

    Jun 25, 2009
    Lake Norman, NC
    1999 185 Bowrider,
    Mercruiser 4.3, Alpha I
    Something else kinda odd on your tabs, looks like the anode is mounted on the bottom of the tab, not the top?
     
  11. hottoddie

    hottoddie Well-Known Member

    Jan 11, 2012
    Boston/Cape Cod
    1986 Sea Ray 390 Express
    Garmin 4212 Chartplotter
    Garmin 24 HD Radar
    Garmin GSD 22 Sounder
    Garm
    454 Crusaders
    I see that all the time. Standard procedure is to install on the top of the tab only. Putting one on the bottom interrupts the flow of water and reduces the effectiveness of the tab.
     
  12. Strecker25

    Strecker25 Well-Known Member

    Nov 20, 2014
    Rochester, NY
    1998 290 Sundancer
    Twin 5.7EFI/Alphas, Kohler 4kw
    Smaller boat and with IO so sort of apples to oranges but I added the drop fins to our 290 in combination with 4 blade props and dropped min planning rpms by about 500
     
  13. Doc O Rock

    Doc O Rock Active Member

    272
    Mar 23, 2016
    Lake St Clair, Belle Maer Harbor
    1999 380 Sundancer
    twin 7.4 Merc
  14. Mer Sea

    Mer Sea New Member

    1
    Jul 17, 2018
    340 Sundancer 1999 bee drive
    7.4 horizon bee drives
    Hi looking for some help on a 1999 340 sundancer 7.4 vee drives, I am looking for idea’s on reducing fuel usage and best RPM for running at 27 to 30 MPH, I am on the St Lawrence river
     
  15. Mittens

    Mittens Active Member

    501
    Mar 5, 2017
    Huntsville, AL
    2002 340 Sundancer, All Cherry Cabin, Black Canvas.
    8.1 Mercs, V Drives, 4.5kw Westerbeke.
    Same here. Planning to pull my 340 this year and want to have new tabs or parts to make tabs better ready to install. So what’s the best deal. Extend and the side fins?
     
  16. Siboatguy

    Siboatguy Active Member GOLD Sponsor

    232
    Mar 28, 2016
    Holmdel,NJ
    2005 Sea Ray 320 Sundancer
    Twins V-Drives
    2017 5.7 Mercruisers
    I did drop fins first and see what that did... It Def helps and i do notice a big difference. Thanks Tab man...

    IMG_0620.jpg IMG_0625.jpg
     
  17. Mittens

    Mittens Active Member

    501
    Mar 5, 2017
    Huntsville, AL
    2002 340 Sundancer, All Cherry Cabin, Black Canvas.
    8.1 Mercs, V Drives, 4.5kw Westerbeke.
    What kind of boat? And any pics of the bottom side of the tab? Do the bolt heads not stick out in the way?
     
  18. Tabman

    Tabman Member

    697
    Jan 11, 2007
    The Tab Cave
    boatless
    boatless
    If you use pan head, or round head machine screws you will be fine. To the other posters if you post pictures of your existing Tabs that would be helpful in making recommendations.

    Tom
    Bennett Marine
     
  19. Creekwood

    Creekwood Well-Known Member

    Apr 26, 2009
    Oakville and Georgian Bay, Ontario
    '97 330 Sundancer, Raymarine C80 suite with radar, Mercury 310 Hypalon w/8hp Yammie 2stk
    2X 454 carbs w/ vDrives
    Mine is basically same engine Hull etc. Fuel usage is hard to lower appreciable. It’s just expensive hobby. On plane at 3400 rpm is my sweet spot. It’s about 30 mph for me and about 1 mpg (imperial gallons). Fuel burn goes up if I run slower or faster. Next best economy in mpg is cocktail speed but before it starts to plow. Maybe 1200 rpm max. But that’s too slow if you need to get anywhere.

    Fuel is one of the smallest costs of ownership of a boat and the only cost that means you are enjoying using the boat.
     
    Handsome Transom and Siboatguy like this.
  20. Mittens

    Mittens Active Member

    501
    Mar 5, 2017
    Huntsville, AL
    2002 340 Sundancer, All Cherry Cabin, Black Canvas.
    8.1 Mercs, V Drives, 4.5kw Westerbeke.
    I have a 2002 340 only pic I have it tabs is this.
    I also have to ask the down bolt ons how will that work when you slide it on a trailer...
     

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