Bigger Tabs/drop fins/custom on 44 Sedan Bridge

Discussion in 'Bennett Trim Tabs Vendor Forum' started by Ray K, Feb 8, 2018.

  1. Strecker25

    Strecker25 Well-Known Member SILVER Sponsor

    Nov 20, 2014
    Rochester, NY
    1998 290 Sundancer
    Twin 5.7EFI/Alphas, Kohler 4kw
    Tom, I don't want to side track this thread but just a general question about something mentioned earlier. Does Bennett recommend against having an anode on the running surface of the tab for all installations? Our 290 Sundancer has the anode on both sides
     
  2. Tabman

    Tabman Member

    673
    Jan 11, 2007
    The Tab Cave
    boatless
    boatless
    At the factory we put anodes on the top only. On most Tabs it's one half of an R-3 rudder zinc. It provides the right amount of protection and we have been doing that for a very long time.

    Tom
    Bennett Marine
     
  3. PlayDate

    PlayDate Well-Known Member SILVER Sponsor

    Dec 25, 2006
    Washington DC
    1994 370 Express Cruiser
    454 Mercruisers
    Tom,

    Your advice is gold. I hadn't thought of putting a zinc just on the top of the Tab. I also appreciate your quick response on the 12"x12" Tab question.

    Thanks!
     
  4. Ray K

    Ray K Member

    51
    Jul 1, 2009
    Toronto, Ontario
    2007 Sea Ray 44 Sedan Bridge
    QSC-500
    Tabman, Thanks for all your info so far. Went to the boat again today to investigate further. My current 12x24 tabs have the short cylinder as I think was mentioned earlier. The top edge of the cylinder where mounted on the transom is 8 1/4" above the top of the trim plane (about 8 3/4" above the bottom of the hull. It is just below where the transom starts to curve rearward into the integrated part of the swim platform that is part of the hull. Obviously this is why Sea Ray choose to use the short cylinder. So I measured the same clearance above the prop pockets. I only have about 7" from the bottom edge of the hull to where the transom starts to curve rearward into the integrated part of the swim platform. I don't think I have enough height on the transom to mount a 12x12 tab here as the cylinder will run into the curved area and will not be able to be mounted. Do you have any details on the minimum transom height required?

    On the issue of the my current 12x24 tabs. Are the drop fins still okay with the short cylinder? If it was possible to fit a 12x30 stock tab in the current location is the short cylinder ok? I did read in another post that tabs up to 12x42 are fine with a single cylinder but it didn't indicate what type of cylinder it was. The retention device you posted about earlier appeared to be more of a device to keep the cylinder from being pulled down and not the force the cylinder is capable of pushing the tab down with.

    20180209_142603.jpg 20180212_130600.jpg
     
  5. Tabman

    Tabman Member

    673
    Jan 11, 2007
    The Tab Cave
    boatless
    boatless
    The short actuator is 11-3/4" overall, so instead of the standard 13-3/4" in the drawing below the dimensions are the same. So you should be able to mock it up to see what will fit.
    [​IMG]stdactheight1
    Adding the drop fins to the existing Tabs will be fine.

    As long as the actuator is in the middle of the Tab side to side you should be fine with a 30" span with the short actuator as well.

    Yes, the retention device is only to take the stress off the actuator when fully deflected. Note: it is for use with the standard actuator only, not the short ones.

    Tom
    Bennett Marine
     
  6. 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
    Ray K. If you want to add the 12X12 tabs between the tunnels and don't have enough room for even the short actuators, consider rigid mounting them with fabricated struts made out of SS tubing. Several CSR members have done similar installs on the older 390ECs. In my case I used an old pair of standard Bennett actuators and mounted the trim planes on about a 5 degree down angle and bolted the actuators thru the transom using 1/4 diameter SS bolts and 4200. They add just the right amount of added lift and reduce the need to use the main tabs when on plane.
     
  7. Ray K

    Ray K Member

    51
    Jul 1, 2009
    Toronto, Ontario
    2007 Sea Ray 44 Sedan Bridge
    QSC-500
    Tabman. I'll see if I can make up a scale mock up with the main dimensions and see how the fit is.

    On the topic of the retention device when are the tabs most susceptible to movement from the boat rocking around when not in motion? When they are fully extended downward or fully up or in the middle. Would be good to know for any tab if certain positions put undue strain on them. Have often wondered as we encountered wakes while at anchor. I certainly have always timed my deployment/retrieval of the dinghy to avoid large wakes when the swimplatform is underwater. It makes for a very large trim tab.

    Hottoddie, I actually have more room above my prop pockets than between them. Between them I could only install 2 8" wide tabs or perhaps one fixed shaped like a V maybe 17" or so. You have a larger area on your boat in the middle. That's why my secondary choice has led me to look at above the prop pockets, especially since they have a flat 12" section. If I was to install a 2nd pair somewhere I would like to have the ability to adjust them, otherwise I would always wonder if the fixed angle I selected was optimal. It is starting to look like this year I may have to do a change to the existing ones and see how it goes. This may not be a bad idea as then I will know what each change did for the boat's performance. Will see how the mock up goes for the pocket tab.
     
  8. 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'm a believer in keeping things simple. If I were you I would have 28"X15" 12 gauge SS plates with 2" drop fins fabricated and piggy backed onto the existing trim planes. You are not subjecting the trim planes to excessive turbulence when at anchor like a sport fishing boat does when backing down on a fish. Don't overthink the situation and make the modification as simple as possible. You can decide later if you need to add the trim planes below the pockets.
     
  9. Ray K

    Ray K Member

    51
    Jul 1, 2009
    Toronto, Ontario
    2007 Sea Ray 44 Sedan Bridge
    QSC-500
    I too was looking to keep this simple but after another visit today I found a few issues after measuring. The good news was I found a fabricator that can either make a larger tab to bolt to my existing one with drop fins or a new one with the hinge in it.

    First I measured above the prop pockets with an actual scale mock up cylinder and tab. There is no way to mount the cylinder properly as the top mount runs into the curve for the swim platform. If a 12x12 tab was added here it would have to be mounted on a shim about 3/4" or so. Then an tapered shim for the top mount of the cylinder would be needed as well about the same 3/4" at the bottom end and tapered down to almost nothing at the top to follow the curve of the hull.

    I also confirmed my short cylinders have a 2 1/2" throw and I need to replace one of the lower plastic hinges as it was loose and the thread is starting to strip. Didn't look too close how this comes off. Anyone know if you can push out the pin in the middle to get the old part off. Didn't look at it that closely. I see at Bennett they have the hinge or the hinge with a SS pin.

    Did some more measuring around the existing tabs when I discovered my transom is not completely flat across. The center of the transom is about 3" further out than the side corners. Since I want to use drop fins on the new tabs I am concerned that they will be essentially be pointing outwards. Did some calculations at home and it looks like the tabs point outward somewhere between 1-2.5deg off straight back 90deg. Now would be the time to correct this by slightly adjusting the sizing and installation of the new tab with drop fins. Should the goal be 90 deg exactly relative to the direction of travel or slightly one way or the other?

    I want to end up with a 28" x 15" tab with 3" drop fins incorporated. The inboard sides will be about 1/2" - 1" shorter to line up the drop fins straight back.
     
  10. juggernaut1

    juggernaut1 Active Member PLATINUM Sponsor

    727
    Apr 19, 2015
    Perth, Western Australia
    2006 38 Sundancer
    8.1S / ZF 63V Drives
    The SS pin can be removed by pushing it out.....although I seem to recall the having remove the machine screws from the tab bracket and tilting the bracket to release the pin as I think the tab bracket has keepers which maintain the SS pin in place during the normal motion of travel.

    Similar to your boat my transom is also not flat and the original tabs are of a canted design such that the sides of the tab are of the same length and are parallel to the running surface of the boat. Essentially a parallelogram shape. My larger tab plate maintained this parallelogram shape to ensure the 3 inch drop fins tracked in line with the running surface of the hull and therefore water flow. You could take a similar approach with the enlarged tab plate thus ensuring the drop fins will track in line with the water flow.
     
  11. Tabman

    Tabman Member

    673
    Jan 11, 2007
    The Tab Cave
    boatless
    boatless
    Up is best and all the way down is worst when it comes to strain on the actuators when backing down.

    Yes the pin on the lower hinge can be pushed out and the threaded part of the machine screw that at attach them to the Tabs functions as a "keeper" for the pin.

    Tom
    Bennett Marine
     
  12. Ray K

    Ray K Member

    51
    Jul 1, 2009
    Toronto, Ontario
    2007 Sea Ray 44 Sedan Bridge
    QSC-500
    Tabman, Is A1114 the best one to order then that comes with the SS pin? My boat is a 2007 so I don't know if it has the SS pin. I'm going there today so I should be able to see. Otherwise it's A1113 I guess.

    Juggernaut, My current 12x24 tabs are perfectly rectangular. Are you saying your originals where a parallelogram to keep the edges parallel to the running surface? They must have been custom then I guess.
     
  13. Ray K

    Ray K Member

    51
    Jul 1, 2009
    Toronto, Ontario
    2007 Sea Ray 44 Sedan Bridge
    QSC-500
    Tabman, Should my goal be to have the drop fins parallel to the centreline of the boat or sides of hull? I don't want to be adding any drag or sideways pressure to them.
     
  14. 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'm not sure but Tabman my be reluctant to recommend adding a "piggy back" trim planes onto your existing ones. It may be company policy so you may just have to "do you own thing". Many of us have done so with successful results. I would do your homework and have the "piggy back" drop fins run parallel to the direction of travel. FWIW I have had the mounting screws become stripped out and thru bolted using 1/4" SS bolts with no problems.
     
  15. juggernaut1

    juggernaut1 Active Member PLATINUM Sponsor

    727
    Apr 19, 2015
    Perth, Western Australia
    2006 38 Sundancer
    8.1S / ZF 63V Drives
    Correct, originals were a parallelogram shape.
     
  16. Tabman

    Tabman Member

    673
    Jan 11, 2007
    The Tab Cave
    boatless
    boatless
    Yes, A1114 is the lower hinge with ss pin. It's good to replace the lower hinge so you have "fresh" threads to receive the mounting screws. Older systems did have a nylon pin.

    The drop fins should be parallel with the center line of the boat. We have made custom parallelogram Tabs for SeaRay.

    Yes indeed we can only recommend our stock Tab sizes as we do not have first hand experience with other applications.

    Tom
    Bennett Marine
     
  17. Ray K

    Ray K Member

    51
    Jul 1, 2009
    Toronto, Ontario
    2007 Sea Ray 44 Sedan Bridge
    QSC-500
    Thanks everyone for your feedback. I'll have a good look at the lower hinges and likely replace as part project. I do understand a formal endorsement of an aftermarket alteration cannot be made. I am going today to make some templates and confirm angles. I will have to also do a parallelogram shape I am sure mine are 90deg. Will confirm though. Too bad as bolting on Bennett drop fins would have been easier. Since I will likely have a bit of custom work done now is my chance to have them done so the alignment to the boats centreline is done. Hope if warms up a bit today as promised.
     
  18. Ray K

    Ray K Member

    51
    Jul 1, 2009
    Toronto, Ontario
    2007 Sea Ray 44 Sedan Bridge
    QSC-500
    An update and a couple of questions for those who have made larger trim tabs. I got the new custom trim tabs back from the SS fabricator. I was lucky that he made me a pair of tabs that included the hinged part so I don't have to deal with bolting, welding or added weight. I ended up with 29" x 14 3/4" with drop fins. If I have to shorten the chord it would be easier to cut then weld on more material. They are also a parallelogram shape to line up with the centreline of the boat exactly. The originals were not.
    I've test fitted them at home to a piece of plywood in my shop as it was too cold out over the last few days to work at the boat. The hinge works perfectly and has the exact same travel as the original which I mounted next to it to verify.

    I am however a bit concerned about the additional weight and the lifting force it takes to lift them from the hydraulic cylinder mount point. I will have to test fit on the boat to see for sure how they function. I know a few of you have similar size mods and especially those who attached the new tab extension to existing ones definitely added some weight to them. I'm just a bit concerned the cylinder is going to have to work too hard to retract them. Anyone encounter any issues with retracting or am I worried about nothing? The originals are 11lbs, new ones 18.5lbs.
     
  19. PlayDate

    PlayDate Well-Known Member SILVER Sponsor

    Dec 25, 2006
    Washington DC
    1994 370 Express Cruiser
    454 Mercruisers
    You may be overthinking it. Retraction shouldn't be an issue because the physics of the water leaving the stern are pushing the tabs up not down. In regards to whether the existing actuator can handle the pressure from the increased surface area. You have increased the area of each tab from 288 sq inches to 427 sq inches.

    That represents a 32% increase in surface area. Perhaps Tabman might opine on whether this will present a problem for your existing rams.
     
  20. Ray K

    Ray K Member

    51
    Jul 1, 2009
    Toronto, Ontario
    2007 Sea Ray 44 Sedan Bridge
    QSC-500
    No doubt I'm overthinking it a bit at this point. I was more concerned with retracting them when not moving forward due to the increased weight. I do remember being able to push them down when the boat was out of the water before and they were all the way up. The new ones need about twice as much upward force. Prior to making these I read that a single actuator can work on a 12x42 tab which is 504sq in so I thought mine should be able to handle the pressure when underway. Also if there are any issues I could always cut the chord back down closer to 12" again easier than adding material if made too small. I am just waiting for a bit warmer weather to do a dry fit on the boat to see how they do.
     

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