Trim Tabs - options - wake surfing (and cruising)

[swatski]

I finished a major part of the install and (I think) it went well! It was a bit nerve-wracking as this design is pretty much THE EXACT FIT on so many levels...LOL. I still need to run the cables/ install the controller but when run off of a spare battery the whole set-up seems to work as designed!

Now, I'm anxious about water testing, but in reality there is not much that I would be willing to change. Really the space of the transom/swim deck and their contours give very little design freedom, and there is only that much size-wise I would install there (safely).

I''l post all the install details and more pics when done, but I won't be able to work on it this week.
But - there is progress - here is the evidence !

Retracted vs deployed:




EDIT: more details to follow, but note that in fully retracted position the tabs' upper surface touches the rim of the actuator's ram. These are the shortest actuators available - to afford maximum upward angle possible in these boats, and also to not obstruct anything connected to or going through/across transom U-bolts/hookups.
These tabs will be completely out of the water at speed and should help list the boat but not obstruct the wake on the surf side. That is the idea, anyway!

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[Bruce]

@swatski, I installed with the folded edge of the tabs down. I feel like it gave my boat a little bit of a keel effect and allows for trapping water. I believe your install is more common than mine. I am curious if you had reasoning for pointing the edges up?

 

[Bruce]

Your install looks great and more out of the way than mine.

 

[swatski]

@swatski, I installed with the folded edge of the tabs down. I feel like it gave my boat a little bit of a keel effect and allows for trapping water. I believe your install is more common than mine. I am curious if you had reasoning for pointing the edges up?

@Bruce -- Oh, you better believe I studied this — before I put 24 holes in my brand new transom!!!

The taper bend (fold) was one thing I went back and forth about the most (and the tabs' hinge is directional, so one can not swap them post manufacture).

In most cases, most "sport" tabs are tapered down (like yours) -- to provide maximum grip and lift. While I believe that with your tabs (12"x12") you would achieve sufficient lift either way, in most boats' the tabs tend to be undersized. Hence there is a tendency for manufacturers to sell those with the fold down, and even make an extra fold in some tabs like some newer Bennetts - just to provide sufficient grip and lift.

Ultimately I decided that I have enough span (width, 16’’ - the max that can be fitted, IMO) and enough chord (length or depth, 9” - which is what many consider optimal) to provide more than enough lift for cruising purposes for the boat. As far as surfing - you would want to go more extreme, but these tabs kind of need to be like my Yamaha - versatile first! So, given I THINK I have enough lift, the rest is about minimizing drag. So - taper up was a no brainer (if that is the case). (Taper serves two purposes, one is to increase the strength - and in this regard "up" or "down" does not matter much; the other is to grip the water to increase lift - here I decided I already had enough lift with the taper up, as above).

The way the tabs work to create lift — some drag must be created. However, drag does not equal lift. The reality is that hydraulic pressure against the angled surface creates lift. Drag is simply a byproduct. The smaller the tab, the greater the byproduct of drag for a given amount of lift. Wider tabs (span) create more lift and less drag than do tabs that are deeper (chord) off the hull.
(that is not some bs random idea, this notion has actually been thoroughly tested and confirmed in the literature - in case you wonder if I'm just running my mouth, LOL)

My other important objective was to also minimize the drag on the surf side for wake surfing (in fully retracted position on that side).

You see, @Bruce, I did think about it! LOL.

I hope the rest of the install and water testing goes well, but the tabs sure look good, and they are kind of massive, hehe:


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[Glen]

and they are kind of massive, hehe:

the 12 year old in me: "That's what she said!"

Awesome!!!!

I'm ready to drive to your place this week and drive a few dozen hours south to find water we can test this in!
(@swatski, you ROCK!!!)

 

[Bruce]

Oh, you better believe I studied this — before I put 24 holes in my brand new transom!!!

I knew you would have!

 

[swatski]

So - I couldn't leave it half-baked, and just had to finish the install tonight. Everything seems to work! The semi-auto controller looks very OEM-ish (good) and is very intuitive. Love the auto-retract feature.

I played around with the placement of the controller before I settled on the spot right on top of the throttles -- probably a winner. Except for one thing: the install -- you need to be a freaking contortionist to do it! -- I'm in so much pain, LOL.

But whatever - it looks good. The 23' of cable provided with actuator was just barely enough for the port side actuator assembly as it runs across the swim platform and then up the gunnel, would probably ask them for few more feet on that side just to be safe. I think I will do a short write-up on the install anyway just to list what I used. The install is simple enough, but there are a couple of tricky-ish steps.




As far as the MLC-1 controller ("semi-auto"), it operates as follows:
(indicators show both tabs fully deployed in this picture)

When you press the top “bow down” button, both tabs deploy simultaneously.
When the bottom “bow up” button is pressed, both tabs retract simultaneously.
When the right “stbd bow down” button is pressed, it first retracts the starboard tab and then, after the right tab is fully retracted, it immediately begins deploying the port tab, and continues if you keep pushing - until fully deployed. And vice versa. (So - by holding the button on either side you can force the boat to list)
If the bow is riding a little high once the roll is corrected, you can press the top button to bring the bow down and still maintain level from side to side. Brilliant!
And then at the end, after switched power goes off, it first retracts both tabs fully and then turns itself off when done.

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[Mainah]

@swatski - Nice work! Must feel awesome that it all came together after all the research. Well aside from the fiberglass splinters and back pain. Could I request that you post some side profile photos both retracted and deployed? Also If you made paper or cardboard templates please save them as there could be one or more interested parties.

 

[zipper]

@swatski - Nice work! Must feel awesome that it all came together after all the research. Well aside from the fiberglass splinters and back pain. Could I request that you post some side profile photos both retracted and deployed? Also If you made paper or cardboard templates please save them as there could be one or more interested parties.

Ditto, NICE, I want to add these, had them on my Sea Ray. Although I probably would not use for surfing but use more for leveling boat as people/loading cause a list. Trim tabs and soundproofing on mods list as soon as it warms up. And new speakers...

 

[jcyamaharider]

Love the install @swatski !! This is going to be a kick butt system when you get it working properly. I only have one question. Please keep in mind that I know this serves for more then one function and I fully support what you are doing.

1. How much ballast are you planning on using to surf?

Listing is key but the way we get the boat to list is actually more of the key. You must displace the water to create a wave. Without proper weight I fell you are just going to lift the boat out of the water more. L:ike jet out of the water and loose " traction" . I have done this and had to add weight to the starboard side of the boat to keep that jet in the water.

Just something to think about when you are doing your testing. And if you do a day of testing I would love to come along and see this system in action!!! Maybe help apply some of what I have learned to get a Yamaha to surf.???

 

[ar240owner]

Love the install @swatski !! This is going to be a kick butt system when you get it working properly. I only have one question. Please keep in mind that I know this serves for more then one function and I fully support what you are doing.

1. How much ballast are you planning on using to surf?

Listing is key but the way we get the boat to list is actually more of the key. You must displace the water to create a wave. Without proper weight I fell you are just going to lift the boat out of the water more. L:ike jet out of the water and loose " traction" . I have done this and had to add weight to the starboard side of the boat to keep that jet in the water.

Just something to think about when you are doing your testing. And if you do a day of testing I would love to come along and see this system in action!!! Maybe help apply some of what I have learned to get a Yamaha to surf.???

I would love to see in person also !! If posible

 

[FloJet]

OK @swatski You the man! Really appreciate this project post. Now how can I convince you to come install mine for me? You name the price

 

[swatski]

Love the install @swatski !! This is going to be a kick butt system when you get it working properly. I only have one question. Please keep in mind that I know this serves for more then one function and I fully support what you are doing.

1. How much ballast are you planning on using to surf?

Listing is key but the way we get the boat to list is actually more of the key. You must displace the water to create a wave. Without proper weight I fell you are just going to lift the boat out of the water more. L:ike jet out of the water and loose " traction" . I have done this and had to add weight to the starboard side of the boat to keep that jet in the water.

Just something to think about when you are doing your testing. And if you do a day of testing I would love to come along and see this system in action!!! Maybe help apply some of what I have learned to get a Yamaha to surf.???

I would love to see in person also !! If posible

Sounds like a Pool-26-Trim-Tab-Warming-Par-te is in order, right??! Lets do that!!!

In the meantime, I will post a bunch of pics.

Now, regarding the rest of the setup: Ballast is and has been the priority!

The tabs should help to intentionally list the boat for sure, but those are really only intended as ancillary there. No replacement for displacement - as you guys would put it! Those tabs' primary function is to smooth out the ride in heavy seas, and frankly I payed more attention to having them retract as much as possible and out of the way when up (and keeping the chord relatively short) -- to NOT disrupt the wake on the wake side. Initially, I considered a recessed mount, such as in the previous hulls with a little step, but that would prevent the tabs from fully retracting up/ out of the way. @OperationROL pointed out at some point how his old tabs mounted that way did not help the wake.

So, to the question of how much ballast? - the answer is: as much ballast as the boat can come up on plane with. Hence my L13 cone mods, which I already have in. There is a couple other things that may need to be tested, but I really want to keep it all pretty simple, as much as possible!

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[swatski]

@swatski - Nice work! Must feel awesome that it all came together after all the research. Well aside from the fiberglass splinters and back pain. Could I request that you post some side profile photos both retracted and deployed? Also If you made paper or cardboard templates please save them as there could be one or more interested parties.

@Mainah I will absolutely post more pics in short order. Most of my work so far has been done under cover of night, LOL.

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[swatski]

OK @swatski You the man! Really appreciate this project post. Now how can I convince you to come install mine for me? You name the price

The idea is to put together a nice write-up and a "to-do" and parts list, I'm hoping we can tap @Bruce skills here, there is a few things that we could also ask the manufacturer to do for us to make those custom plates simpler to install.

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[Bruce]

@swatski, have you mounted the controller?

Mine is on the wall in front of the throttles. I have found that while in really rough water I can use my fingers to adjust the tabs while keeping my palm on the throttles. It looks like the gap is larger on your boat so that may not work.

 

[swatski]

@swatski, have you mounted the controller?

Mine is on the wall in front of the throttles. I have found that while in really rough water I can use my fingers to adjust the tabs while keeping my palm on the throttles. It looks like the gap is larger on your boat so that may not work.

Yep - post #67 above is mounted as in permanent mount. I considered several options, that just seemed like the best one. The JBP Perfect Pass controller mount will go directly above - where the arrow is pointing.


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[blacksapphirez]

I have a question...may be a dumb one...

The jetskis have the adjustable trim on the nozzle....WHY is it that the Boats can't have this same feature?

 

[Mainah]

I have a question...may be a dumb one...

The jetskis have the adjustable trim on the nozzle....WHY is it that the Boats can't have this same feature?

I have been thinking the same thing. If the place diverter/steering nozzle from a yamaha ski fits on a boat why not give it a try? Just temporarily fix the position of the diverter to point full down and see what happens. Or make your own external cable for the testing. Of course you won't have reverse in this test so just plan for that. This is something that I want to try but have no idea when I will get around to it.

I would think that with a diverter pointed down there would be less wash on top of trim tab type functionality. Of course with the length, weight, and drag of a boat this may not work well. It does work for classic berkley pump jet boats though so I don't see why not.

 

[captras]

@Mainah I will absolutely post more pics in short order. Most of my work so far has been done under cover of night, LOL.

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Great post and info. Seriously considering this mod. Will really be interested in the results. We wakeboarders and ski, no surfing yet, but most interested in the ride affect in rougher water. Thanks for taking the time to write all this and share with the group