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Wakeplate on A20


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Dsthomas05

Hi all,

I was wonder if anyone had thought about or tried removing the floating wedge on the A20 and replacing it with a wakeplate (i.e. center trim tap)?

Now, before you slam me too hard, hear me out. 

I've been in looking at getting a new boat for some time now and I'm really ingested in the crossovers because we like to do it all (ski/wakeboard/surf). Of the newer boats, the A20 is smaller and lighter than most, including the purpose build crossovers like the VTX and GS20. Now there's more to be a good crossover than weight but it's a good start point  since its harder at remove weight than to add it. The boat is also much more affordable than most boats of its vintage, fits in a standard garage, and looks pretty cool.

Unfortunately, the wake hull keeps the noise high and the wake big until about 36mph (as its designed to). Above that, the noise seemed to come down and the wake really flattened out (at least that is what I saw when test driving a 2020 model).

This made me think that a wakeplate could he used to push the noise down at lower speeds and flatten the wake out.  This would make the boat much better to ski behind, especially at lower speeds.

The wakeplate had other advantages as well, including better hole shot, handing chop, and adjusting steepness/length of the wake when surfing or wakeboarding. Our 20ssv has one and I'm always adjusting it to tweak the ride and the wake.

The obvious down side is you loose 600-1200lbs of down force that the wedge provides. However, with the available ballast and the weight of the boat, I don't think it will be missed [especially coming from a 2800lbs boat with 1200lbs of ballast, as i am :)].

Love to hear your thought.

Dave

PS- not sure if this is the best place for this thread so let me know if I should move it.

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I would think that converting from a floating wedge to a power wedge might give you the best of both worlds.  Having a wedge that will provide lift should get you a better wake than having a tab that just pushes the nose down.  It isn't clear to me why you couldn't use an old outboard trim/tilt unit to make a power wedge that would not crap out every other week and would withstand the forces for both down and up lift.  Yes, you would have a few pesky problems to solve, but that's most of the fun anyway.

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i think @justgary has an interesting idea if you like projects; maybe a trim tab addition could help without losing the wedge for surfing or wakeboarding.  or if you were looking new, an A20 that has the power wedge (though i've gotten beeps when i have the wedge down at >25mph, so skiing at 30+ with it may be a no-no).

id say it comes down to are you seriously skiing or just whipping side to side for fun?  a ski boat isn't gonna surf well and a surf/wakeboard boat isnt gonna ski "well."  both 'can' do the other items, just depends where you'd rather have good performance vs messing around.  @ahopkinsVTX is probably the best to chime in on that crossover VTX-experience but probably comes to priorities/use case.

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Posted (edited)

This is on my project list (that I've put off 2 winters now) on my 2006 21 Vride.

I want a better ski wake by effectively moving the engine a foot forward. I want to keep the nose down in chop. I also foresee a slight length increase for surfing (if I can increase weight anywhere and have a slightly negative degree tab)

I purchased a set of 24x12 lenco trim tabs and actuators to try to achieve this. What I'm running into, the Malibu drain plug is on the hinge, so I need to slot and braise the pin. Like the MasterCraft plate, the exhaust requires the hinge plate to be reduced. Finally, I don't have a lot of height for the actuator below the swim deck, so a 0 or - angle is going to be more difficult for me.

I also want to add some angle brackets as fins to the tab so that the turbulence will be softer (MasterCraft does this)

My context is coming from a moomba outback where the wakeplate turned an temporary/almost tournament slalom boat into a great wakeboard boat (or vice versa, as the outback was a great wake hull with the tab up)

 

 

 

 

Edited by smileysteve
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1 hour ago, smileysteve said:

I want a better ski wake by effectively moving the engine a foot forward.

Talk to @Woodski.  Removing all of the rest seats and swapping a few engine parts can move the CG forward quite a bit, as can moving the fuel tank.  He has done several mods to improve his ski wake.  Last I heard, he was looking for an aluminum engine block.

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@smileysteve - commenting based on @justgary tag, but are you asking or simply commenting?  Moving CG forward does typically improve the wake for slalom and given the engine is a significant % of total weight, to your comment, it will move the CG.  Based you your approach, I would do a weight location calculation to see if adding the (heavy) tabs and required hardware would actually move the CG and get you what you are after.  The tab effectively is a transom hook modifier or simple a hull trim adjuster.  As Gary noted, there are a lot of components that can be shifted, or made lighter to also move the CG of these boats.  All my mods / changes without adding any tabs moved the CG a foot forward, of which an aluminum block is one of them.

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I was commenting on the tab setup and my plan to help @Dsthomas05

I am not terribly interested in an effort of replacing the block, moving my fuel tank, or modifying any seats.
 

3 hours ago, Woodski said:

Moving CG forward does typically improve the wake for slalom and given the engine is a significant % of total weight, to your comment, it will move the CG.  Based you your approach, I would do a weight location calculation to see if adding the (heavy) tabs and required hardware would actually move the CG and get you what you are after. The tab effectively is a transom hook modifier or simple a hull trim adjuster. 

A single tab and lenco strut aren't heavy (for example, about ?10% of the swim platform weight). Modifying the hook on the fly is exactly the effect that I am pursuing with my project. (a wake plate that functions very similarly to Moomba's wake plate on their ~2008s Outback, LS, LSV etc models to make their boats more crossover)

The "effectively a foot forward" is only to suggest that by extending the hull 24x12 the rest of the boat's weight will be spread out slightly at even a slightly negative angle (but especially with more hook as, it would plant the bow)

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Dsthomas05
On 5/21/2022 at 5:19 PM, CaptainMorgan said:

i think @justgary has an interesting idea if you like projects; maybe a trim tab addition could help without losing the wedge for surfing or wakeboarding.  or if you were looking new, an A20 that has the power wedge (though i've gotten beeps when i have the wedge down at >25mph, so skiing at 30+ with it may be a no-no).

id say it comes down to are you seriously skiing or just whipping side to side for fun?  a ski boat isn't gonna surf well and a surf/wakeboard boat isnt gonna ski "well."  both 'can' do the other items, just depends where you'd rather have good performance vs messing around.  @ahopkinsVTX is probably the best to chime in on that crossover VTX-experience but probably comes to priorities/use case.

I love the idea of using the wedge to create lift but the drag at 30mpg would significantly (it increase expediently with speed) and would put a lot of stress on the hull. That is why the boat is beeping at you. I'm sure you could do it but I'm not sure if I'd want to take that on for DIY project.

As for my skiing, I mostly just like cutting hard and whipping side-to-side. Currently, we have a 20SSV and I ski at 30mpg, 15off, with the wakeplate fully down.  The wake is hard but small enough to absorb with your legs. However, it gets significantly bigger at lower speeds.  If I could get a similar result to our current setup I would be happy.

 

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1 hour ago, Dsthomas05 said:

I love the idea of using the wedge to create lift but the drag at 30mpg would significantly (it increase expediently with speed) and would put a lot of stress on the hull. That is why the boat is beeping at you. I'm sure you could do it but I'm not sure if I'd want to take that on for DIY project.

As for my skiing, I mostly just like cutting hard and whipping side-to-side. Currently, we have a 20SSV and I ski at 30mpg, 15off, with the wakeplate fully down.  The wake is hard but small enough to absorb with your legs. However, it gets significantly bigger at lower speeds.  If I could get a similar result to our current setup I would be happy.

 

Makes sense. I'd go read the vtx review @ahopkinsVTX wrote (it's on here somewhere). Sounds like he is a skier who also wants to do other things and the vtx soundss decent at all. (I've never ridden behind it myself)

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ahopkinsVTX
6 minutes ago, CaptainMorgan said:

Makes sense. I'd go read the vtx review @ahopkinsVTX wrote (it's on here somewhere). Sounds like he is a skier who also wants to do other things and the vtx soundss decent at all. (I've never ridden behind it myself)

 

@Dsthomas05 Here is my review of the latest generation vtx. It truly does everything great and the other generations do too. It’s a long post but I think is worth it.

Honestly I think the key to getting an a20 to ski well is bow weight, little to no weight in the stern and finding the best line length for the ski wake. And maybe using the power wedge 3 in lift. I think removing it for a wake plate would hinder the boat much more than benefit it. 

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Dsthomas05

@ahopkinsVTX awesome review.  thanks for sharing.

The VTX has definitely been on my list for a long time but it's always been just out of reach for me on cost. Also, my understanding is anything new then 2016 wont fit under a 7ft garage door, which is not ideal.

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Dsthomas05
13 hours ago, ahopkinsVTX said:

I think removing it for a wake plate would hinder the boat much more than benefit it.

I'm interested in why you think this.

Do you think the wedge is that beneficial for surfing and wakeboarding, or do you think the wakeplate won't be affected at pushing the noise down, or something else?

I can tell you from experience, on our boat, the wake plate makes a huge difference. It also gives me control to adjust the boat on the fly, depending on the condition and where people are sitting. I know the hull is different and this matters a lot but the basic physics should be the same (create lift at the back by pushing the water down).

On the other hand the floating wedge just creates downforce but this could also be achieved by adding ballast to the back of the boat. The big benefit of the wedge is that it doesn't take up space in the boat and it doesn't take time to fill. However, today's boats have a lot more room and much better pumps so these benefits are less important. 

Now if the boat had a power wedge it would be a different story, removing it would be a really hard sell. However, assuming the boat didnt come with one, adding it after the fact would be much harder and more expensive than adding the wakeplate.

Really interested in you thoughts on this.  

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ahopkinsVTX
50 minutes ago, Dsthomas05 said:

I'm interested in why you think this.

Do you think the wedge is that beneficial for surfing and wakeboarding, or do you think the wakeplate won't be affected at pushing the noise down, or something else?

I can tell you from experience, on our boat, the wake plate makes a huge difference. It also gives me control to adjust the boat on the fly, depending on the condition and where people are sitting. I know the hull is different and this matters a lot but the basic physics should be the same (create lift at the back by pushing the water down).

On the other hand the floating wedge just creates downforce but this could also be achieved by adding ballast to the back of the boat. The big benefit of the wedge is that it doesn't take up space in the boat and it doesn't take time to fill. However, today's boats have a lot more room and much better pumps so these benefits are less important. 

Now if the boat had a power wedge it would be a different story, removing it would be a really hard sell. However, assuming the boat didnt come with one, adding it after the fact would be much harder and more expensive than adding the wakeplate.

Really interested in you thoughts on this.  

Well specifically for the manual wedge you maybe right? If it was the power wedge then it is a no brainer. In my experience the wedge, manual or power out perform wake plates for wake creation tuning though. It would be an interesting experiment.

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@Dsthomas05 why not look at trim tabs on both sides, vs. in the middle? I spoke with Rob Andrus (Evolution) and he said on an earlier version of the tabs that he put them on an older VTX and said that it looked to flatten the wake, but didn't get any feedback on someone slaloming behind it. I probably have tabs on the list for my 04 LSV in the next year or so. I am not sure how the tabs would affect the wake going that fast. Also people have created the "hook" where the transom meets the bottom of the hull. On BOS there is talk of caulking a temporary bead, or taping bondo knives to the transom with 1/4 of an inch or so sticking out for testing. From there I believe folks have permanently installed a hook with marine tex or something similar.

 

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Dsthomas05

It's a good question, I guess I just assumed that it wouldnt work well since trim tabs have been around for ever yet no ski boat manufacturer had used them yet. At least not as a way to improve the wake for ski. 

I always thought trim tabs would be nice because you could even out the wake without moving people or shifting ballast around. 

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@Dsthomas05 I am probably 1-2 years off from putting trim tabs on, maybe next spring considering I have used up all of my "wife bucks" on plumbing in pumps and other misc boat stuff and equipment. If you beat me to it, let me know!!!

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