Trim Tabs - options - wake surfing (and cruising)

[BigAbe75]

@swatski its 65 degrees and sunny this afternoon... you testing on the water yet?

 

[Mainah]

@swatski its 65 degrees and sunny this afternoon... you testing on the water yet?

Sounds warm enough to me.

 

[swatski]

@swatski its 65 degrees and sunny this afternoon... you testing on the water yet?

Darn I so wish... I'm completely swamped with work cases for the next couple of days...
I think I'm going to go crazy.

EDIT: IDK. I may quit my work. The River is calling.

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[Ed Miranda]

@swatski, Did you use screws to attach the actuators to transom - or use a bolt/nut through hull? Reason I ask is I noted Bruce's install he placed his actuators close to the Ubolt where the hull is thicker - but not sure you have yours that close to take advantage of that. I believe the screws in the Lectro installation calls for 1 1/4' screws and the hull around that area (further from the Ubolt) is probably around 1/2" thick I think or less perhaps. Thanks

 

[swatski]

@swatski, Did you use screws to attach the actuators to transom - or use a bolt/nut through hull? Reason I ask is I noted Bruce's install he placed his actuators close to the Ubolt where the hull is thicker - but not sure you have yours that close to take advantage of that. I believe the screws in the Lectro installation calls for 1 1/4' screws and the hull around that area (further from the Ubolt) is probably around 1/2" thick I think or less perhaps. Thanks

I will post the install details w/pics, but just in short - yes I used screws.

I agonized over what to use. Ended up with:

• self-tapping round head SS #12 1 1/4" (for the top actuator mount)
• pre-drilled w/ 11/64 drill bit (through hull, about 1/2")
• w/countersink (just to chamfer gelcoat, very slight, shallow, wide angle)
• bedded with 3M 5200 (regular)

I considered using the "epoxy-plug" technique (drilling a larger hole for an epoxy plug and redrilling to the screw size), but with those FRP hulls I'm not sure that is the best way to go. I ended up drilling small pilot holes and, to my surprise, discovered there was wood inside -- no idea the exact thickness but I would guesstimate the thickness to be about 1/2" (see below).

The transom built is quite different between model years, @Bruce install used the embedded wood enforcement for the transom U-bolts (left), which inside the transom look identical to my 2012 190 (on the right):
Bruce's (left) My 2012 190 (right)

@Bill D had his U-bolts enforced in the 2010-2015 24 hull, I wish the new hull afforded similar access:

The new (2015+ 240) hulls are quite different. There is sound-deadening material stuffed up in the narrow space in the swim deck, and the access is obstructed by water boxes. I could take those out, of course, but it is a major PIA/project. I could reach the U-bolt (kind of) in the corner of the hull but could not reach the space directly above where the top actuator mounts are installed - roughly 8-9" inside of the U-bolts/tie-downs.
Here is the best pic I could take with my arm stuck under the transom, note the strbd U-bolt in the far corner under the deck:


The install went well, I was able to torque those screws real tight, have a pretty good feeling about it. The key, I think, is the exact hole sizing. In my case - with #12 SS screws (from Menards, self-tapping, sheet metal, full thread) - the best fit was w/ 11/64 drill bit -- which performed best in scrap fiberglass panels I used for testing the fit. Screws from different sources will fit a bit different so I would always test that.

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[swatski]

So - we took off for a quick water test today! the weather was just too nice.

WOW. Those tabs are dynamite! I have to say - surpassed my expectations completely. I wasn't trusting my math and worried with those super short actuators, the range may not be adequate and the tabs would under perform. What a nice surprise!

I am just quickly showing a couple of things here, will run more tests next weekend, hopefully, and then will write it up and report with pics.

First of, the controller works very well and is very intuitive. When I hit and deploy both tabs simultaneously (pushing the "bow down" button) the bow gets almost stuffed, when cruising at 25-30 it is a dramatic effect and the speed drops at least 5mph, the stern pops up about a half of a foot. Almost funny. I was very excited to see such a DRAMATIC adjustment in attitude.

Looking strait down from the swim deck:

Tabs up (retracted) - normal 25-30mph cruise


Tabs down (both fully deployed) - the stern lifts up and rides on the tabs



The same as above but going faster cruise, about 35mph:

Again, tabs up (retracted) - normal fast cruise


And here -- tabs deployed down - riding on the tabs -- the boat really bogs down!



And below are some shots of the deflected wake with one tab deployed (the boat is listed on purpose and kept in strait line - with HARD steering):

Port side (only) deployed


Starboard side (only) deployed


The boat can be steered very effectively with tabs only.


Now, when up at speed the tabs are completely out of the water so, not surprisingly, there is no effect on handling or top speed which is still somewhere in 48-50 mph (7,700-7,800 RPM) range most days in my current my set up.



This system should be a plug and play for simple attitude adjustment, but there is A LOT of testing and work to be done to make it work for surfing. I think the one point most can agree on is that when it comes to wake surfing, any hull/boat would probably gain some benefit from an adjustable trim tab. And in this regard, my tabs were designed with Hippocratic oath in mind (first do no harm) - short actuators and maximum retractability, but appear to still work great!

I think this is going to be one great system - I am cautiously optimistic .

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[FloJet]

There you go! Very glad you are liking it so far. I'm glad you are making progress with it all too. Everyone is anxiously waiting for the final results so we can all stay broke! Keep up the Awesome work!

 

[CrankyGypsy]

AWESOME! looking great!!!

 

[ar240owner]

Man we would of hit the river with you !!!!

 

[buckbuck]

WHERE ARE THE 10 MPH PICTURES?!!!
I want to see if you can enhance the wake.
Take some St Lunatics with and weigh the boat down.
Can't wait for your update.

 

[swatski]

WHERE ARE THE 10 MPH PICTURES?!!!
I want to see if you can enhance the wake.
Take some St Lunatics with and weigh the boat down.
Can't wait for your update.

Oh, that is coming. Keep in mind that without (a lot of) ballast those tabs just lift the stern up.
You really want me to give up my day job, don't you? LOL. Bad Buck.

EDIT: In all seriousness, the un-ballasted wake behind our boats is not pretty at any speed, and at 10mph is just down right ugly. The tabs alone make it just a different kind of ugly. I did not want to cause too too much confusion here.
However, the fact that those do have such big influence is very good -- as long as we can figure out how to harness it.

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[captras]

I guess being on a river, you dont get much in the way of rough water. Would love to know how it affects the ride with 2-3 foot swells.

 

[jcyamaharider]

I guess being on a river, you dont get much in the way of rough water. Would love to know how it affects the ride with 2-3 foot swells.

Don't let being a river fool you, it can get VERY rough.

 

[swatski]

I guess being on a river, you dont get much in the way of rough water. Would love to know how it affects the ride with 2-3 foot swells.

Oh, I'm not even remotely anxious about that after my first water test (I don't mean to sound snide at all). The first test confirmed the range of the boat's attitude adjustments. These custom tabs appear to be robust, meeting and exceeding all expectations beyond my (fairly conservative) calculations/estimates. I also personally regard this design to be about as heavy duty as I would be willing to test in the hull.

It would be very cool to see anyone else coming up with an alternative design/project. There are plenty of ideas out there. I would be thrilled to test side by side. Might get a chance with @1948Isaac but would predict his and mine work very similar in the rough based on the surface area and the range of motion.

As far as cruising in the rough we all know what good tabs can do in Yamaha hulls - based on @Bruce's posting alone I would argue tabs should be a factory option. In 2015+ hulls @1948Isaac is the only one I know of and he vouched to install tabs in his next Yammie before any other upgrades.

I will sure be reporting on the cruising performance, the big river can get real nasty in the big Alton pool, and if it does not I will be tracking to Bimini later this year. That said, at this point I consider that part of the project to be completed.

The remaining open issues/goals are: 1. Long term reliability and structural robustness of this particular design/install; 2. Making those tabs work in creating a killer surf wake.

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[captras]

The only real alternative to the conventional trims tabs that I have seen are the Volvo Penta QL trim tabs. Would be interested to see a side by side test/review!

 

[Bruce]

The only real alternative to the conventional trims tabs that I have seen are the Volvo Penta QL trim tabs. Would be interested to see a side by side test/review!

I had a set of Volvo QL trim tabs but decided to sell them and switch to Lectrotabs before installation. The QLs have to install on a flat vertical surface. If there is any bend to that surface they will be permanently damaged. They stick straight down from the hull. The adjustability is to how far they stick down. The main reason I decided not to install them was thier lack of ability to adjust the attitude at low speed.

An Aussie on YJB did have a set of QLs on a first generation 240 and reported positive results when boating at speed.

 

[swatski]

The only real alternative to the conventional trims tabs that I have seen are the Volvo Penta QL trim tabs. Would be interested to see a side by side test/review!

@captras Be my guest! Those certainly work, @dan144k and I believe other Yammies here run with those. There are several special considerations where the "interceptors", as QL concept is known, absolutely shine.

The QL concept is well proven in many applications over decades of use. Mostly in large ship and military applications but also in some recreational and small commercial vessels where mounting space behind the transom is a consideration and fuel efficiency is NOT. Acting essentially as “water brakes”, those are very effective in converting dynamic water pressure and producing lift at the transom/stern. Generally possible to install almost anywhere, some have a servo inside hull with shaft through transom, so those can be mounted in some boats where where not having traditional tabs makes sense -- for example for on deck storage in a case of a tender on a yacht. In case of a Yamaha, there is just enough dead space under the swim platform for custom built (traditional) tabs.

While they both work to provide lift, traditional trim tabs do work way better at relatively lower speeds which for many vessels is where trim tabs really shine and where real fuel savings can occur.

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[1948Isaac]

So - we took off for a quick water test today! the weather was just too nice.

WOW. Those tabs are dynamite! I have to say - surpassed my expectations completely. I wasn't trusting my math and worried with those super short actuators, the range may not be adequate and the tabs would under perform. What a nice surprise!

I am just quickly showing a couple of things here, will run more tests next weekend, hopefully, and then will write it up and report with pics.

First of, the controller works very well and is very intuitive. When I hit and deploy both tabs simultaneously (pushing the "bow down" button) the bow gets almost stuffed, when cruising at 25-30 it is a dramatic effect and the speed drops at least 5mph, the stern pops up about a half of a foot. Almost funny. I was very excited to see such a DRAMATIC adjustment in attitude.

Looking strait down from the swim deck:

Tabs up (retracted) - normal 25-30mph cruise
View attachment 51130

Tabs down (both fully deployed) - the stern lifts up and rides on the tabs
View attachment 51131


The same as above but going faster cruise, about 35mph:

Again, tabs up (retracted) - normal fast cruise
View attachment 51132

And here -- tabs deployed down - riding on the tabs -- the boat really bogs down!
View attachment 51134


And below are some shots of the deflected wake with one tab deployed (the boat is listed on purpose and kept in strait line - with HARD steering):

Port side (only) deployed
View attachment 51135View attachment 51136

Starboard side (only) deployed
View attachment 51137View attachment 51138

The boat can be steered very effectively with tabs only.


Now, when up at speed the tabs are completely out of the water so, not surprisingly, there is no effect on handling or top speed which is still somewhere in 48-50 mph (7,700-7,800 RPM) range most days in my current my set up.
View attachment 51125View attachment 51126


This system should be a plug and play for simple attitude adjustment, but there is A LOT of testing and work to be done to make it work for surfing. I think the one point most can agree on is that when it comes to wake surfing, any hull/boat would probably gain some benefit from an adjustable trim tab. And in this regard, my tabs were designed with Hippocratic oath in mind (first do no harm) - short actuators and maximum retractability, but appear to still work great!

I think this is going to be one great system - I am cautiously optimistic .

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The install looks great... i am happy you can tell the huge different they make. Just wait untill you get very heavy waves , you put them down and you will get a nice ride regarless off

 

[swatski]

The install looks great... i am happy you can tell the huge different they make. Just wait untill you get very heavy waves , you put them down and you will get a nice ride regarless off

@1948Isaac Like it or not, you are the grandfather of trim tabs in 2015+ 240 hulls, LOL.
It is a tight fit, and I wanted to be able to still mount the wake wedge, or a flap devise - which turned out good with enough clearance.


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[1948Isaac]

@1948Isaac Like it or not, you are the grandfather of trim tabs in 2015+ 240 hulls, LOL.
It is a tight fit, and I wanted to be able to still mount the wake wedge, or a flap devise - which turned out good with enough clearance.
View attachment 51507

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Lol lol...Great job on the wake wedge. Looks great... Have fun with it