Designing surf tabs out of auto trim tabs

[wolff supra21v]

Here is what I was thinking, please any input on this would be great.
I am trying to make a shopping list for black Friday/ cyber Monday.

Here is my shopping list right now.

(2) Lenco Trim tab Edge mounted 9"Wx12"L Part # 20159-001 Cost $94 each
(2) Lenco Actuator 4-1/4 stroke Part # 15059-001 Cost $210 each
(2) Lenco upper actuator mount Part #15070-001 Cost #18 each
(2) Lenco Lower actuator mount Part # 50015-001d Cost $16 each
(2) Lenco 20' wiring harness Part # 30133-103D Cost $33 each
(1) Lenco Switch Led indicator kit Part #15070-001 Cost $320
(This switch kit has the wrong part number this one is for a 2-1/4 stroke actuator I need the one for a 4-1/4 stroke actuator but the said it is the same cost) (I am trying to get a part number for it now but it may be a special order the local lenco dealer.)

If I ordered today I would be looking at $1062 plus any taxes or shipping if required.


Okay now here is my plan

Install the two trim tabs Like they are designed for but use a longer stroke actuator to use them as Surf tabs.

I was looking at a kit with the standard 2-1/4" stroke actuators but the plates will only go down to about 22 degrees.
with the 4-1/4 stroke actuators it will go down to about 60 degrees. this was verified with cardboard and a tape measure this weekend.

I think I will be good on the controller it has an input on it. So if it does not have 12 volts on it, it automatic raises the plates to the all up position. (I was going to put this in a rocker switch to turn the system off and on with.) It also has led indicators to tell you were the tab is.

This weekend I winterized my boat and a cut out a piece of cardboard for the tabs.
Here is what I came up with.

1. The back of the supra 21v has a 1/2 in surface change where I want to put the tab.
My plan is to use a piece of Trex decking I have left over to shim this level.

2. The lip of the platform will be in the way. and it is going to be tight against the platform.
It should not be a problem cutting 2 or 3 inches of the lower lip off the platform(It is the part that is against the back of the boat no one should be able to see this.). I might have to raise the platform a inch or two.

[trayson]

I'll be following your progress, that's for sure.

[wolff supra21v]

Broke down and order all the parts for the trim tab system. I was hoping to save some money but all I save was shipping taxes and just a little more than that.
everything should be in 5 to 7 days. but I still have 3 plus months to get in on the boat for testing.

[wolff supra21v]

Everything but the controller has came in for the system. it is suppose to ship on the 28th I am hoping to move the boat from storage to the work shop Friday or Saturday this week. to start the install.

I also have a second guy looking at redoing the vinyl today.

[viking]

If your going to build a system do it right and do an NSS type like this guy:
http://www.wakeworld.com/forum/showt...ht=surf+system

Best DIY System I've seen to date!!

[bergermaister]

Right.... Look how nice and square his back corners are transitioning from bottom to transom. No step.

Badazz work though.

[jasonwm]

I can't comment on the design specs of other systems, except to say there are two schools of thought here; either create lift to list the boat, or create drag to force the boat to crab. SurfGate falls in the former category, NSS and other systems, like Swell, land in the latter.

Testing on our product (which is decidedly different from anything else that has been posted thus far) has shown that unless you're going with the drag model, deploying the tab any further than 10-12 degrees just makes it act like a brake, and eliminates the lift that is needed to list the boat at speed.

Obviously this is all dependent upon the design specs and engineering for the system and what it is trying to do. But for anyone thinking they'll just bolt some trim tabs onto the transom of their boat, I think it would be a mistake to have them deploy very far. Obviously this needs to be modeled and tested in detail, and I could absolutely be wrong, but I feel pretty confident in the results.

[trayson]

I can't comment on the design specs of other systems, except to say there are two schools of thought here; either create lift to list the boat, or create drag to force the boat to crab. SurfGate falls in the former category, NSS and other systems, like Swell, land in the latter.

Testing on our product (which is decidedly different from anything else that has been posted thus far) has shown that unless you're going with the drag model, deploying the tab any further than 10-12 degrees just makes it act like a brake, and eliminates the lift that is needed to list the boat at speed.

Obviously this is all dependent upon the design specs and engineering for the system and what it is trying to do. But for anyone thinking they'll just bolt some trim tabs onto the transom of their boat, I think it would be a mistake to have them deploy very far. Obviously this needs to be modeled and tested in detail, and I could absolutely be wrong, but I feel pretty confident in the results.

While I appreciate your explanation, I can't say that I agree completely with it. You're saying that the goals of a surf system are to list or crab. I don't really agree. The goal of a surf system is to delay the convergence of the wakes.

There are members here that have made "ghetto gates" that don't have an angle at all and essentially extend the running surface of that side of the hull, but in a straight line, not in the Malibu 22 degrees. I guess it could be argued that even with a straight ghetto gate that it's effectively making the boat crab because you're kind of placing a straight rudder on the non-surfside corner. But then we're talking semantics.



I guess the only thing that I really disagree with you on is that NSS is in a fundamentally different school of thought from the surfgate. they're not. And that's why Nautique LOST the lawsuit and is paying millions to Malibu.

I retrofitted my own manual version of an NSS onto my supra. Mine was modeled after the Nautique's in that it extended 3" OUT from the hull and only .75 to 1" DOWN. My boat sat level, just like the G23's do when they're deploying their NSS. (I've ridden a G23 and a G25 with NSS.) Likewise, my NSS most certainly affected the turning of my boat. we got used to only turning away from the surf side when it was time to come back and pick up our rider.

The NSS is most certainly affecting the side of the hull, just like the Surfgate. however, there's an inverse relationship between length of the delayed convergence device and the length necessary for it to be effective. My NSS stuck up 90 degrees from the hull. At full deployment it only needed to be 3". The surfgate is 17.5" and is at a 22 degree angle. The members that have made 0 degree ghetto gates have found that they needed to be even longer than a surfgate because they had no angle of deployment.

I would imagine that my principle holds true on downward deployed devices, that the length and surface area are inversely related to the angle of deployment...

This seems to hold true in the marketplace.
Surfgate = BIG with a moderate angle
Moomba Flow = smaller with a 90 degree angle
Centurion quicksurf = big surface area with a more moderate angle
NSS = small with a 90 degree angle
Mastercraft Gen 2 = more moderate angles with big surface area
MB Sports Gen 2 = 90 degree angle with a smaller surface area beyond the hull (basically an NSS with a different method of deployment)

The Supra Swell seems to be the one that I can't quite nail down as far as the angle vs. surface area. Because it's certainly a reasonable amount of surface area, but they crank that thing all the way down as well. Yeah, it's likely acting like a brake in addition to delaying the convergence? And maybe that's having it function like a surf system and a "wedge" type device at the same time?? Not sure. Sadly it's one of the systems I didn't get to ride last year. I will try to get on one in May.

I'm by no means an expert. But I do have first hand experience with a handful of surf systems...

[viking]

Looking forward to seeing this all come together. Pics pics pics along the way!

[ISUclonesrule]

Any further work/design done on the trim tab surf system? I know it's winter and you are probably not in a big hurry but this seems like a great project! Thanks for posting!