Bigger Tabs/drop fins/custom on 44 Sedan Bridge

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

  1. Ray K

    Ray K Member

    50
    Jul 1, 2009
    Toronto, Ontario
    2007 Sea Ray 44 Sedan Bridge
    QSC-500
    My 44 Sedan Bridge is a bit stern heavy and have been reading posts where others have dealt with this issue with larger trim tabs or drop fin addons. I have the GHS hydraulic lift on the boat which adds about 600lbs when it's empty and at a 25mph cruise I still have close to full tab to achieve the best speed. I'm only one or two quick touches of the tab button off full when loaded with fuel, water and gear, much more than my last boat. Was at the boat today (winter storage) and confirmed it currently has OEM Bennett 12" x 24" tabs. There only seems to be 28" along the transom from the prop pocket to where the deadrise flattens out as it approaches the chines. The other problem even if I was to change to a 12" x 30" tab I cannot relocate the cylinder due to underwater lights on that side.

    Many of the posts I have read where various modifications where made where on express cruisers between 30 to 40 feet. Not sure if having a slightly larger tab with drop fins custom made would help a heavier boat like this. Also have the partial hardtop option on this one. Not sure what that weighs. I am looking to just improve the performance a bit as having that much tab down always is adding drag and counter acting the lift to some degree.

    The current tabs are mounted about 1/4" up from the bottom (was surprised as I thought they should be flush) of the running surface so there would be space to perhaps have a larger tab fabricated and attached to the bottom of the existing one without taking anything apart. Maybe 26" x 15" with drop fins. If I had room for the 12 x 30 that would be the way to go but I really don't see how they could be installed as I think it will be necessary to relocate the cylinder
     
  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 a hull extension and trim tab extensions put on my boat. If you have prop pockets you couldn't do the hull extensions but take a look at my tab extensions.

    They were bolted to the original tabs and mounted below the originals so they wouldn't interfere with the cylinders.

    [​IMG]
     
    The Bill Collector likes this.
  3. Ray K

    Ray K Member

    50
    Jul 1, 2009
    Toronto, Ontario
    2007 Sea Ray 44 Sedan Bridge
    QSC-500
    That's quite a lot of extra lift. I do have prop pockets and have heard of some adding a 2nd set of tabs over the tunnels but am reluctant to go this far as an experiment. If it doesn't work it's a lot of holes to fill. Curious though on your modifications, did you keep track of the difference in performance before and after? Did you do it all at once or the tab extensions first? I think in my situation my only option is to do a mod to the tab to make it a bit longer and or wider and maybe the drop fins. Hoping to get some good feed back on the boats of this size and improvement.
     
  4. gdavis67

    gdavis67 Member

    50
    Mar 1, 2017
    Saugatuck, MI
    1990 390ec
    Twin 454 Mercruiser T 340 with Hurth drives
    Ray, look in the 390 EC sticky for the posts people have left regarding adding either 12x12 tabs at the centerline or a fixed tab. Their results have been impressive. Lower speed to achieve planing attitude and lower RPM's at cruising speeds. I added mine this winter and am adding drop fins (available from Bennett) before it goes back in the water. The additional tabs can be plumbed directly into the existing lines. I had the same issue you have with my 390EC. I had to run with tabs fully extended to get on plane with even a half load of water/fuel. The 390 has a heavy stern down attitude. I'm not familiar with the stern shape of your hull, but if you have prop pockets you should be able to get 12"x12" to fit.
     

    Attached Files:

  5. Ray K

    Ray K Member

    50
    Jul 1, 2009
    Toronto, Ontario
    2007 Sea Ray 44 Sedan Bridge
    QSC-500
    I'll have to go down to the boat and take some more detailed measurements. I do have flat topped prop pockets and have heard some have put tabs here. Don't think there is enough room right at the keel but will check. I don't have any issue getting on plane but the fact that I have so much tab applied at cruising speed makes me think I could definitely make this more efficient and maybe have a better cruising attitude and speed. Have a friend with the same boat minus the hydraulic lift and hardtop and he does cruise faster at the same rpm.
    Keep everyone posted on your before and after speed/rpm at different speeds after you get in this spring. Will be interesting to see the change.

    I don't have a pic of the centre of the transom but you can see the difficulty in installing a 12" x 30" tab as the cylinder can't really be moved and I only have about 28" of flat surface between the prop pocket and the curve leading into the chine. I'll take some better pics when back at the boat.

    Sea Ray 44 Sedan stern starboard.jpg
     
    Last edited: Feb 9, 2018
  6. 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.
    Ray, I wasn't able to do a performance comparison because I had them put on when I bought the boat. The boat came from Michigan and when I sea trialed it I noticed it took some application of tabs to help it get up on plane. Not much, but a bit of tab helped.

    The boat yard in Portland, OR where I had the recommissioning done is owned by a guy with a marine engineering degree and an unlimited tonnage master license. He said he was familiar with those boats and knew about the boat being stern heavy. He suggested the tab extensions and I agreed.

    Now, getting up on plane requires almost no tabs, even with full fuel and water and loaded up for a vacation trip. The boat runs on plane just great without tabs now so I'm pleased with the modification.
     
    The Bill Collector likes this.
  7. 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
    A 28X15 SS fabricated plate with 2" drop fins centered and attached to the existing tabs will make a substantial difference. You could have them welded on or attach them your self using several SS pan head machine screws. Make sure the SS plate is heavy enough gauge and decent quality.
     
  8. Ray K

    Ray K Member

    50
    Jul 1, 2009
    Toronto, Ontario
    2007 Sea Ray 44 Sedan Bridge
    QSC-500
    Gdavis, I checked and I don't have enough room in the centre to add the 12" x 12" tabs. A fixed one could possibly installed here like Gofirstclass has installed on his. I guess my prop pockets are larger and the area between the two is not large enough. There is room above the pockets which have a flat area of 12" wide but I am reluctant to make too big a change at once. I think maybe this season I would make some sort of change to the existing tabs and see how it goes.

    Hottodie, I think I will inquire about a slightly larger custom trim plane with drop fins at a local machine shop as there is nothing between the 12x24 and 12x30 size directly from Bennett. If I didn't have the underwater lights I could have probably installed the 12x30 and moved the hydraulic cylinder to centre them but not now unfortunately. Any idea what the gauge of SS Bennett uses? Is it 14GA or greater? I suppose I could just add the drop fin kit for a season too and see what the difference would be. I wonder if a shop could just make a whole new drop fin trim plane slightly larger to swap out.

    Gofirstclass, I was looking at your setup again. Any concerns with the supports for the fixed trim plane on the bottom of the swim platform with the pressure pushing up?

    Has anyone ever just added drop fins on the 12x24 regular tabs and done nothing else with any significant change? Funny thing I was looking at a photo of my other boat today (Cruisers 370 express) and it has 12x30 tabs. A smaller, lighter boat with bigger tabs. Had no trimming issues with this boat even with the tender loaded. Crazy.
     
  9. Ray K

    Ray K Member

    50
    Jul 1, 2009
    Toronto, Ontario
    2007 Sea Ray 44 Sedan Bridge
    QSC-500
    Here are some photos of what space I have to work with. I had posted the question in the Sport Yacht section but maybe more people will see it here.

    20180209_142550.jpg 20180209_142603.jpg 20180209_142640.jpg
     
  10. 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
    Looking at the pictures reinforces my first suggestion. 28X15 with drop fins should be perfect. I think a local shop may have some trouble fabricating the hinge. If so just "piggy back" a new plate onto the existing. BTW Bennett suggests you do not install the zinc anode on the bottom of the tab, only the top. It interrupts the flow of water on the bottom off the tab.
     
  11. Tabman

    Tabman Member

    668
    Jan 11, 2007
    The Tab Cave
    boatless
    boatless
    If it were me I would install drop fins on the existing tabs, and add tabs w/o drop fins over the prop pockets.

    Tom McGow
    Bennett Marine
     
  12. Ray K

    Ray K Member

    50
    Jul 1, 2009
    Toronto, Ontario
    2007 Sea Ray 44 Sedan Bridge
    QSC-500
    Tom, thanks for your feedback. I have considered that. I could possibly fit 12x12 ones here but would have to be a short cylinder as the one I have on the existing tabs (it has 3 rings on it) due to the shape of the hull above the area. I will have another look in the engine room as this would be right around where the rudder tie bar and tillers are. The starboard side is very hard to gain access to the area as it's behind the generator. How much lift do you think the drop fins would add to my existing 12x24 tabs? Does the effect make if similar to a larger tab without drop fins? Any issues with the boat's stern yawing a bit in rough weather and sideway force on the drop fins? Also what thickness is the SS used in these tabs and drop fins? thanks

    Hottoddie, I already noticed the zinc on the bottom when starting to look into the tab situation and it definitely shouldn't be there. I didn't install it that way. It currently has one on the top and bottom. The bottom one will be removed when some of the snow around here melts and it warms up a bit and when I start working on this project. Thanks very much for the observation though as I could have missed it.
     
  13. Strecker25

    Strecker25 Well-Known Member SILVER Sponsor

    Nov 20, 2014
    Rochester, NY
    1998 290 Sundancer
    Twin 5.7EFI/Alphas, Kohler 4kw
    Is this true for all boat sizes? I never thought about it but our little 290 has the anode on both sides
     
  14. 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.
    Ray, I'm not sure you would have to relocate your cylinder. If you were to install a new tab plate below your existing tab you could make it as long as you want (fore to aft) just so it's not long enough to interfere with your hydraulic swim platform. You could also extend it out to the side to make it wider. I played around with one of your photos to see what it would look like and he's what I came up with. Not fancy, but I think you'll get the idea.

    [​IMG]

    As to my hull extension, it's been there almost 8 years and it's still solid. It's made from stainless plate (sorry, don't know the gauge) that's screwed up onto the bottom of the hull and braced with those two brackets.

    Looking at your photo above I think you could do a similar idea, putting it above your pockets, but I'm not sure how effective it would be. Anything you added in terms of lengthening the running surface would give you more lift. But, keep in mind I ain't no nautyical anginear so I'm just guessing.
     
  15. Ray K

    Ray K Member

    50
    Jul 1, 2009
    Toronto, Ontario
    2007 Sea Ray 44 Sedan Bridge
    QSC-500
    Gofirstclass. Thanks for the mockup. In the photo of the starboard tab I have 2" to the left to the prop pocket and 2" to the right before the curve starts to happen that goes to the chine. So if I want to widen and leave the hydraulic cylinder alone and centred I can do a 28" wide tab max. If my underwater light was not there I could have probably done the stock 12x30 tabs and moved the cylinder (don't really want to fill a lot of holes under the waterline). My other boat has a 12x30 tab that on the outboard side went past the flat part towards the chine. I do like the idea of the drop fins to give it some more lift.
     
  16. Tabman

    Tabman Member

    668
    Jan 11, 2007
    The Tab Cave
    boatless
    boatless
    The Tabs are different gauge stainless depending on their size. I believe the drop fin add ons (DF12) are 12 gauge. In my 20 plus years with Bennett I wave not seen an issues with yawing or side force. I have seen them damaged by forklifts and travel-lift slings but that is a different story.

    The drop fins will add some lift and are worth it. But given the weight aft on your boat there is no substitute for additional surface area. That's why the second set of tabs would be my choice.

    Using the short actuators will be fine, and we have some options to connect the tubing to the actuator in confined spaces if need be.

    Tom McGow
    Bennett Marine
     
  17. 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
    FWIW when I added the tabs between my tunnels I fix mounted them at a slight (about 5*) down angle. I had a spare pair of old Bennett actuators that I mounted to the tabs and transom without plumbing them into the hydraulic system. Those along with the oversize area I added to the QEM Sea Ray tabs has transformed a stern heavy beast into a well behaved boat that will stay on plane down to 12-14 knots and 2700-2800 rpm. I

    I did notice that in August when out on a whale watch off Cape Cod that the oversize trim tabs were extending and retracting quickly while drifting in 2ft seas. I could sea the dash tabs indicators going a little crazy. No harm was done however. I believe this is the reason Bennett doesn't like to recommend added "cord" the trim plane dimension. It can add a lot of stress to the cylinder mounting screws while drifting in rougher water. You hear story about fishing boats losing trim planes when offshore. I think this is the reason.
     
  18. Tabman

    Tabman Member

    668
    Jan 11, 2007
    The Tab Cave
    boatless
    boatless
    That is exactly our concern. Fishing boats can put a lot of strain on the Tabs when backing down on a fish, as can installing "over sized" tabs.

    We manufacture a "retention device" designed to take the strain off the actuator when the tab is forced all the way down by water pressure from above.

    [​IMG]Retention_Device_Insta_Instr_2.jpg~original

    Part number RD001. It can be special ordered from a dealer.

    Tom McGow
    Bennett Marine
     
  19. PlayDate

    PlayDate Well-Known Member SILVER Sponsor

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

    Tom,

    Bennett tabs are one of the most reliable systems we see on boats. Personally, I have only rebuilt the cylinders once in 15 years of owning my boat.

    I installed a hydraulic lift years ago which added more weight to the stern. Over time the lift and adding progressively heavier dinghy + motor combinations means longer time to plane. I'm considering adding a couple of 12"x12"s to my boat to help it plane better. One of the posters on this thread indicated that they tied the smaller tabs into the larger tabs hydraulics. Is this what you would recommend?
     
  20. Tabman

    Tabman Member

    668
    Jan 11, 2007
    The Tab Cave
    boatless
    boatless
    Yes, that is one of the advantages of hydraulic systems. The new tabs can be simply "teed" into the existing ones on the same side. They will be a bit slower but will work together as one big tab.

    Tom
    Bennett Marine
     

Share This Page

Show Sidebar