Vertical trim tab (Surfgate) testing results

[High altitude]

Thanks for the update. Were you able to go ropeless? The actual wave looks nice, but a bit small. Of course, I realize pictures can be deceiving. I am looking forward to reading about your second attempt.

[jjsaustin]

Thanks for the update. Were you able to go ropeless? The actual wave looks nice, but a bit small. Of course, I realize pictures can be deceiving. I am looking forward to reading about your second attempt.

I have only been surfing 3 times and the last 2 were goofy foot (which I was able to go ropeless goofy foot). So when I got up this time regular, although I had slack in the rope, it felt like I was goofy foot and unstable... go figure.

I was encouraged enough though to drill a hole in my swim platform bracket for a mounting point to clean up some of the mounting hardware.

Here are the pics of rev 2: The gate is raised up by 1.5-2 inches, it is angled similar to the hull (not vertical), and it has a lip on it. This should solve the water washing over the tab and allow me to add more ballast.

I hope to experiment varying the angle of the tab. My theory is if the tab is out too far, it will delay the convergence too long and the wake washes over from the port side softening the lip. This is similar to the wake without any gate, but the wash is coming from the opposite side.

[jjsaustin]

Below are today's results. I was able to get a some pics of the wave with and without the tab. I think the pictures are pretty clear that the tab is having significant effect on the wave. Without the tab, it is totally unsurfable.

Water was still coming over the lip, but not as much as before. Unfortunately, I ran into mechanical problems with the tab set up before we got to surf.
1) First the lip on my tab came off and a lot water was shooting over the tab again, so we had to dial down the starboard ballast to 1/2 tank.
2) The adjust-ability on the gate got hosed, so I had to resort to using vise grips and I did not experiment as much with the angle of the tab.

Pic 1: No tab and port filled and starboard half fillled.
Pic 2: Tab (lip on tab intact) with port and starboard filled
Pic 3 and 4: Tab (no lip) port filled and starboard half filled with son surfing ropeless

I was able to go ropeless briefly, but the sweet spot was tough to stay in. Perhaps with full ballast and the next gen tab it will be easier.

I pretty much have the starboard wake delayed enough and I don't think adding more delay to the convergence will help. What I can now see is clearly messing up the wave is the prop that is washing up and over the wake from the port side of the boat. It is hard to explain without seeing a picture, but the angle of the wake from the port side of the boat is shallower than the angle of the prop wash. So the prop wash eventually is higher and rides over the wake from the port side of the boat. I think the only thing that will over come the prop wash is more weight and displacement on the port side.

Gen 3 Tab:
The next gen tab will be taller (more above the water and perhaps add some depth too).
I may consider adding some length to the tab to have a shallower angle and perhaps have the water flow more smoothly around the tab versus having to abruptly hit the tab.
I will also add a stronger lip (the original one only had screws that went into the tab about 1/2")

Any thoughts or ideas?

[High altitude]

Interesting results. It is amazing to see how similiar some of the results are to my SN. The biggest observation (and one I'm not too happy about it) is that the gate really only happens to help shape up the wave. The Nautique hull seems to react to weighting a bit more than the Malibus. Thus, the advantage of the gate might be smaller. A possible test (if you have the time) would be to just fill up the port side and run that with no gate. That is really the "baseline" because that would be close to an optimal setup versus both sides full. (Does anybody have the ideal setup for a 226 on the port side??)
I think deeper and taller are going to help a bit but I think as you said before, the delayed convergence is already happening. When you start to weight one side you will need the extra depth because the whole thing will start to come out of the water as the opposite side is leaning more.
I can't think of much more. The weather is nice again in Colorado so I might have a chance to try a few things this weekend as well. Thanks for sharing the results. -Marc

[DealsGapCobra]

I love that you guys are trying these and posting the results, I am considnering makeing one for my boat too. I will never have a "real" wave but would love it if my crew can learn to go ropeless. As for suggestions, I would assume that Malibu did a bunch of tests so I would model them a bit more closely with defelction angle. Based on that, yours is too far out which is probably what is causing a lot of the water going over the top.

Keep up the good work and please keep us updated!

[jjsaustin]

Marc, I tried just filling the port side and having the starboard empty, but did not seem much different than with full port and half full starboard, but I will try again because I think it should make a difference.

I wanted to experiment with the deflection angle on my last outing, but ran into technical problems. I am getting plenty of delayed convergence, so I think I can go with a smaller tab with less deflection. I think if you delay the convergence too much you can reduce the volume of the overall wave. So more is not necessarily better.

The other item I am questioning is could the Hydro-gate technology from the SV211 help to diffuse the prop wash. As I mentioned previously, once the starboard wake is delayed, I think prop wash is now the biggest culprit in messing up the surf wave. By deploying the Hydro-gate just a little, it would help to flatten the prop wash and diffuse it.

BTW: I am not aware that Hydro-gate was an option on the 2006 era 226 boats, but I could be wrong. On later 226 boats I think it was an option and now it is automated on the new boats and called Hydro-Plate.

[scottb7]

In case it helps, here is a very good pic of the malibu tab.

[jjsaustin]

My Gen 3 tab worked pretty good. Both pics are with full port ballast only. I was able to go ropeless several times relatively easily. I tried adding half and quarter tank of starboard ballast, but my son said the wave was not as strong (he's only 13, so not an expert by any means). This design seemed to be the best so far. It is ~14" tall and 13" wide on top and 15" wide on bottom. It is completely vertical and has ~2" lip angled at 45 degrees. I think for Gen 4 tab I may try to reduce the tab width to 10". I want to see how narrow is too narrow for the tab.

First pic tab.

Second pic with tab.

There are a couple pics of the tab itself and then a pic the non surfside wake

I tried uploading a short mp4 surf video, but it says 25MB is too large, but it may not be a supported file type.

[DealsGapCobra]

If the first pic is without the tab and the second is with, it looks like it was more than worth the effort! Thanks for sharing the info.

[High altitude]

Nice work on the gen 3 tab! Looks like it cleans the wake up pretty nice. Were you able to experiment with the angles?

I had a chance to run a few more tests this weekend. This is probably it for me for the season because the water temp was 46. I have a drysuit and don't mind surfing or skiing at that temp (air was 60) but it is just too cold to be fiddling with things under the waterline.

For this test I changed the angles and added weight to the surf side. I was opposed to adding weight on the surf side originally because my original goal was to had a system where I could weight the back but use the trim tabs to optimize each side. I have now abandoned that goal. My Nautique just doesn't put out a useable wave unless it is leaned over.

Because of this I will be looking at using a completely detachable system so I know it won't effect my ski wakes. I think the size that you are using is about right. The angles did make a difference. I think I am going to use less angle than more. I know that's not very specific... but I have not found the optimal angle yet. The angle really effected how the wave started to form. A greater angle (more towards perpendicular with the hull) tends to delay the convergence more and ends up shortening the wave. It becomes steeper but it has a very short pocket and is less useable. A reduced angle kept a longer, more natural wake, but helped clean up the lip (like in your pic 2 above). It also had a side benefit of helping with steering. When I used a greater angle, steering became almost impossible at slow speeds. Sorry I don't have pics, but it was just me in the boat when I had the tab on. (My neighbor showed up to surf but we both surf goofy so we removed it)

Over the winter I am going to work on a few things. The first will be to refine my ballast system (I use 3 Johnson pumps) and build out the area to hide all the ballast in the back. I will then work on fully adjustable tabs for each side and a quick connect system so that I can attach while the sacs are filling.

Keep posting if you change anything. The work you are doing is awesome! -Marc

[jjsaustin]

Thanks for the feedback.

Yes the pics are with/without the tab (same setup) and I agree it is well worth it it you have time to experiment.

Marc, I have various holes in the rod for adjustment (see pic 1). I started out in the 2nd hole and the wake was OK. Once we moved it to the 3rd hole, the wake clean up and my son said is was great and just wanted to surf. BTW: I just have a long screw resting in the hole and it pull in and out to move holes, it is not even attached. I have 1 more hole in the rod that I should have tried, but honestly, I'm not sure it is going to get much cleaner given all that is going on back there. Maybe next time.

As for the angle, I have included various pics. If I had to guess, I would say the angle of the tab is ~135 degrees from the hull. The blue yardstick in pic 2 is roughly perpendicular to the hull. When the setup was in the 2nd hole it was probably ~140-145 degrees from the hull. Also, I thought the tab was vertical, but in pic 3 you can see that it is tilted about 20 degrees (the yardstick is vertical and the camera is tilted slightly). In pic 4 you can see the position of the tab is behind and at the same depth as the one chine and roughly the same angle as the hull and goes all the way up to the rub rail.

If I find that I can keep the tab on and fold it up to the swim platform without interfering with the ski wake then I may go with an adjustable system. Otherwise I am fine just to have a quick connect system that I take on/off. I removed/installed this setup several times as we switched riders yesterday. All I have to do now is pull the hinge pin so it only takes a few seconds and can be done while we are switching the ballast.

Eventually, I will clean up the entire mounting bracket and have a metal shop create me a simple bracket at the proper angle. I could permanently mount it to the swim platform brace with screws to eliminate the wood.

Next time out, I will try position 4, and possibly an even narrower tab (Gen 4 maybe 25% smaller) and try out some different scenarios (ie. does shorter tab in position 4, the same/better/worse that the current tab in position 3). I would like to get to the point where the wake starts to degrade so I know I went as small as I can. Working with wood is so easy to experiment with different size tabs.

Hope this helps.

[kmgs]

Hey guys - first, thank you for posting all this detail, it is greatly appreciated.....you're certainly innovators!

Please continue to keep us posted on progress, as I am sure many of us will be using your testing as the foundation for our fabrication! Thanks again!

[High altitude]

Nice pics. The system you designed is nice and the results speak for themselves. Here is a link to a guy on another forum who has done a lot of work. It might help you. The results on his boat have been simply amazing and has reinvigorated me to try make an automated permanent setup. I think I need to work on optimal weighting, then the angle and size of the gate. I will work this winter to come up with the right testing regimen as well as all the parts. It would be nice to build the automation (pistons and a switch) but I'm slightly worried that I would make a mistake that would be hard to fix later on. The automation would allow me to make dozens of angle changes in a short period of time which would be very nice. I will have to think about it some more to determine my best course of action.


Here is the link: http://www.themalibucrew.com/forums/index.php?/topic/40613-teakgate/

[High altitude]

Also, here is a link to all the work that went into building the above-mentioned gate as well as several others. Fascinating reading (other than my posts at the end )

Link: http://www.themalibucrew.com/forums/...poormans-gate/