Bigger Tabs/drop fins/custom on 44 Sedan Bridge

I can only speak from personal experience (and mine are probably heavier than yours as the enlarged tab is welded to the bottom of the existing tab), but I've had no issues in the 12 months I've installed my larger tabs. If anything, I'd probably change out the lower hinge/stainless steel pins so you have fresh mounting hardware.

..........and don't forget to post pics.
 
Juggernaut, I've already ordered new lower hinges with the stainless pins and thanks for the feedback. I will definitely post pics and detailed stats on performance. I find too many threads die after something is implemented and one never knows the end result. I'm not relaunching the boat until mid April so it will be a while for the in water test though. It's 2deg C here today so I'm not sure when I'll even get them installed again. Getting very anxious though.

I have a question on a post I believe you made once regarding having them auto retract at lower speeds. How did you accomplish this as I've only seen the auto retractor connected to an ignition sense wire to retract when the engines are off.
 
Ray, my new tab additions were bolted directly onto the existing tabs. I don't know the measurements or the weight, but the weight of the new tabs was added to the weight of the existing tabs.

In 8 years of operating them I have had zero issues with them. But then, I don't use my tabs much. When I do use them, it's more often balancing the boat left to right to compensate for uneven loads (fuel and water) than bringing the bow down.
 
Ray K said:
I have a question on a post I believe you made once regarding having them auto retract at lower speeds. How did you accomplish this as I've only seen the auto retractor connected to an ignition sense wire to retract when the engines are off.
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...sorry to hear about the weather.....we've got 30's C here in Perth WA at the moment.

I installed the Mente Marine ACS which auto retracts when not on the plane. So at no wake speeds the tabs are fully retracted (and of course when backing into your slip). Whilst the MM ACS does have an optional ignition sense wire it's not needed for this functionality as it uses GPS to determine speed.
 
Mine are 30 X 15 with drop fins and have no issue retracting them for the last 7 seasons with a single cylinder.
 
Got the new trim tabs installed yesterday. Going to replace the hinges with the ones with SS pins still. Will launch mid April. Anxious to see the difference these will make.
20180318_163948.jpg 20180318_163936.jpg
 
HOLY CRAP THOSE ARE WAY TOO BIG!!

Just kidding. They look good. Now I'm waiting to hear what you think of them.
 
Just an update.....

On my 370 the tabs are a trapezoid shape and were 28"(span) x 9"(chord) in dimensions. They were marginal before I added the hydraulic lift and the added weight made it worse. I believe the chord length was the problem. Tabman had recommended drop fins but that presented a problem since the Bennett Drop Fin Kit ($29) has a chord length of 12". To solve it, I extended the chord on each tab by 3" to accommodate the drop fin (instead of cutting the drop fin to 9").

In my case, that involved adding a 6"x28"x.125" stainless plate to the bottom of each tab and attaching the drop fins. I bolted the plates on with stainless bolts and locknuts so that I could try the configuration out before welding them on. I wasn't thrilled with the thought of 1/8" drag line on the span of the bottom of the tab and the drag of rounded bolt heads but it was a way to try out the idea for this season.

On Tabman's recommendation I also ditched the bottom half of the zinc (I removed the zinc after I took the picture below).

The results are pretty impressive. At cruise (3200 rpm), the boat picked up 2 mph. Equally impressive, is that it jumps up on plane which it has never done. Additionally, when backing the stern would seem to have a mind of its own. With the drop fins....it tracks much better. I have owned the boat for 18 years and from a performance point of view, this is one of the best/least expensive upgrades I have done.

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Ray K said:
Got the new trim tabs installed yesterday. Going to replace the hinges with the ones with SS pins still. Will launch mid April. Anxious to see the difference these will make.
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That looks great! After reading this, and other threads, I think I’m going to call Bennett in the fall and see if they have anything to replace my current 24”x12” tabs on my 410 Sundancer with.
Ideally, I’d like to keep it as simple as possible by just swapping out the tabs, staying with single actuators, and leaving the actuators where they are.
I know that I could probably get better results with a whole different set up, but I’d rather just keep it as simple as possible and get some improvement.
 
The boat has been in the water now for 2 months and have done a variety of trips every weekend and compared the results with previous years fuel burn. I have found that I can run with a little less tab now to find the sweet spot for speed but not much less. When changing the tab position it does respond a bit quicker as they are larger. My fuel burn, mpg, speed has not changed noticeably at all much to my disappointment. I did notice that my engine load in smartcraft has gone down about 2-3% overall at cruise speed rpms ranges.
I did however have my props scanned over the winter and there was a minor tweak to the cupping and leading edge as they were slightly off and I was trying to correct the slight difference in WOT rpm between the two engines. The tweak would have increased rpm slightly. Port is still about 20rpm slower then Starboard though. May have gained about 10rpm on both so I'm thinking this is factoring in to the performance figures a bit. I'll have to check this again later in the season and with different fuel and water loads on the boat. Perhaps this boat is just heavy enough that a but more tab doesn't have as great an effect than on a lighter model. I am still glad I made the change as they are now more appropriately sized to the boat. Will also have to see when taken out of the water in the fall if everything held up with the added load on the cylinders, hinges etc. Will have to decide if I want to explore more tabs in the centre like a few others have done.
 
Ray K said:
Got the new trim tabs installed yesterday. Going to replace the hinges with the ones with SS pins still. Will launch mid April. Anxious to see the difference these will make.
View attachment 54256 View attachment 54257
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Hi Ray, I know it’s been quite a number of Months since you posted this, but would you mind providing an update on the results of your modifications? I’m looking at doing a similar thing to my 44DB. AEO.
 
Yes I did. The first attempt had good results but the chord of the tabs (length) was a bit too large. I can really get the bow down now. The problem was it was too hard to get the tabs down once on plane if I had raised them up too much. Last winter I cut about 1 1/2 off the chord. I can now get them down further when onplane to below the sweet spot. I can still not get them all the way down unless I slow down a bit. I could cut another inch off to probably achievethis. I may do this over the winter or not.
 
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Ray K said:
Yes I did. The first attempt had good results but the chord of the tabs (length) was a bit too large. I can really get the bow down now. The problem was it was too hard to get the tabs down once on plane if I had raised them up too much. Last winter I cut about 1 1/2 off the chord. I can now get them down further when onplane to below the sweet spot. I can still not get them all the way down unless I slow down a bit. I could cut another inch off to probably achievethis. I may do this over the winter or not.
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I’m glad to hear you had a positive result. So many stories of modifications with little changes reported, hence I’ve all but given up... may I ask in your opinion what the plane dimensions should be to get the right balance? Thanks.
 
Ray K said:
Yes I did. The first attempt had good results but the chord of the tabs (length) was a bit too large. I can really get the bow down now. The problem was it was too hard to get the tabs down once on plane if I had raised them up too much. Last winter I cut about 1 1/2 off the chord. I can now get them down further when onplane to below the sweet spot. I can still not get them all the way down unless I slow down a bit. I could cut another inch off to probably achievethis. I may do this over the winter or not.
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This seems like a time when a second set of actuators would be required. They are not that expensive and the installation shouldn't be that hard at all.
 
After the 2018 season and taking off about 1 1/2" of the length (chord) I now have tabs about 29 x 13 1/4" with drop fins. The tabs are a parallelogram shape as the transom is not completely 90 to the sides. I could reduce the size a bit more still to be able to push them all the way down while at cruising speed but I may lose some of the gains I've made. During the 2019 season with the reduced size above, if I'm at a cruising speed of 24-25mph I can't get them all the way down again, but if I slow down to below 18-20 I can get them down lower then I would need them. I will probably leave them for now this way.

With the original 24 x 12 tabs I would have them almost fully down all the time to get the best speed. Now I start off with them down and when getting on plane the bow stays very low and I am usually starting to retract even before fully on plane. Now I have them about 4-5 quick presses up from fully down to achieve the best speed so they are not angled down so far to give much better lift.

I would have loved to have added 2 cylinders to each tab, but due to the location and centering them there was too much interference on the transom. Either the hydraulic platform frame on one side or the thruhull underwater lights on the other side. This would be the best solution but so far it's worked out much better than the original setup.

I could probably cut them back to 29 x 12 and then be able to get them fully down with the single cylinder as I feel the drop fins and having them a parallelogram shape really makes them capture a lot of water. But then they are going to angle down farther again.
 
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