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View Full Version : The basics of Surf Systems (and platform modifications)



trayson
08-26-2014, 12:13 PM
I've had some questions from people that are newer to the surf system game, so I'll start a thread here to hopefully answer some questions and help out more than just one person.

What is a surf system?
A surf system is any device that's added to your boat that operates on the non-surf side to delay the convergence of the two wakes coming off the back of your boat. By delaying the convergence, it cleans up the wave on the surf side and lengthens the pocket. It also has the tendency to allow you to weight your boat evenly (or more evenly) as opposed to slamming the rear corner. When you add a surf system device, there's an inverse relationship between the angle to the hull at which it deploys and the length of the blade/tab. (for example, a surfgate is easily a foot an a half with a shallow angle {~20 degrees} while the NSS is only 3" but is at a 90 degree angle to the hull)

Why would you want a surf system?
The ability to evenly weight the boat allows for a more comfortable experience for the driver and passengers. It also allows for quick changes from regular to goofy because you're not having to drain ballast, move ballast and refill ballast. Often a surf system will allow you to run less overall weight and still maintain a clean, surfable wave. Sometimes a surf system is used to clean up or lengthen the wave.

What are the drawbacks of a surf system?
Many people are adverse to making permanent modifications to their boat. If you're going to do the direction of a temporary system, then you've got something that you have to figure out how to attach and stow when not in use. You've got to have a little DIY knowhow and be willing to fabricate and EXPERIMENT.

Most will attest that to get the absolute BEST wave period, that there's "no replacement for displacement". Simply put, MORE WEIGHT is typically hard to beat when it comes to getting the BEST wave you could get. That said, life is about tradeoffs and those of us with surf systems are using them to get a good/great wave while simultaneously making things better as far as boat drivability, fuel consumption, convenience, etc.

What surf systems are out there?
There are a handful of surf systems out there, and most of them have been copied or retrofitted in some way or another.

1) Malibu/Axis Surf Gate.
http://theskimonster.com/files/theskimonster/ckfinder/images/Malibu-Surf-Gate-Deployed.jpeg
This is the original. it's a gate on the side of the boat that deploys at around a 20 degree angle. They are powered by a Lenco trim tab actuator and are basically functioning as a sideways trim tab. in the most recent 2014 versions, they have been upgraded with faster actuators so the gates will deploy/retract in about 3 seconds, allowing transfer tricks from regular to goofy and back.

2) Natique Surf System (NSS) {also used by Pavati}
http://www.nautique.com/img/nss/feature-wakeplate-large.jpg
The NSS is a blade that is deployed on the edge of the hull. It extends about 3" out and about 3/4" to 1" down. It had varying levels of adjustability to change the wave from surf to skim. It is likewise power actuated and enables on the fly side to side transfers.

3) Supra Swell (Also MB Switch and sort of Mastercraft Gen2 surf system)
http://www.marine-products.com/blog/wp-content/uploads/2013/11/SURF-CLEAN-CUSTOM-SHAPED-WAVES-WITH-SUPRA-SWELL.jpg
Supra stepped into the game by putting special shaped trim tabs on each side of the BOTTOM of the transom. Supra and MB systems will actually deploy a trim tab fully horizontal on the opposite of the surf side. Mastercraft does the same type of thing, but I don't think their tabs go as far down (so they're accordingly longer).

4) Moomba Flow
http://www.idahowatersports.com/shop/wp-content/uploads/2014/05/2014-05-02-15.09.jpg
Moomba is kind of unique in that they stepped up with a manually actuated surf system. It's a blade that can be deployed in 4 different settings from more outward to more downward. It pivots with a spring loaded locking pin.

What system is the best?
Honestly, all of the systems have their advantages and disadvantages. Each manufacturer will praise their own system. Some offer adjustment of the wave, some offer simplicity, some offer a price advantage. But all of them are attempting to do the same thing: Delay convergence of the wakes coming off the rear of the boat.

What DIY systems have been created to mimic/retrofit what the new boats are getting?
Keep in mind that some of the boat manufacturers have filed for patents on their systems. And many of the boat manufacturers have copied other people's systems or made knockoff's anyway. I am not a lawyer and can't advise what's okay and what's not okay when leveraging someone else's ideas. But I guess I will say that you're less likely to encounter problems if you don't try to sell retrofitted surf systems that greatly resemble something one of the boat companies has a patent on.

The first system to be retrofitted was of course the surf gate. There are many iterations of this that have been done. You can search on these terms and find lots of write-ups that have been done on these. The first two are automated and permanent, the last two are manual and able to be taken off when not in use.

Poor Man's Gate
Teak Gate
Cornrickey Surf gate
Ghetto Gate (note, there are versions of this that come out at an angle to the hull like the Malibu surf gate, and versions that come straight out as an extension of the hull. Both work but the straight ones tend to be longer)


A few of us have retrofitted an NSS style system onto our boats. I chose to go this way because the rear hull of my boat is basically flat and it would allow me to have something that's out of the way when not in use that I DON'T have to take on or off. This is a manually actuated system with blades that slide out sideways from the hull. It's made from HDPE and stainless bolts. The install on this is more time consuming than some and materials aren't too bad but are more than some of the basic designs. It's most certainly permanent and required drilling quite a few holes in my hull.
My write-up: https://forum.supraboats.com/showthread.php?16402-Trayson-s-DIY-quot-Supra-Surf-System-quot-(SSS)-modeled-after-the-NSS

There are always going to be critics about the extra force/strain that's being put on your hull. All I can say is think it though and install things as robustly as you can. Obviously, if you wreck your hull, it's not my fault and I take no responsibility! Ha!

I know there have been a handful of retrofits of surf tabs. I mean, all you really have to do is get a trim tab kit and mount it up. I think the most effective designs are those that deploy fully downward like Supra Swell, and not many people have been able to fab up the extra bracing/reinforcement for the trim tab actuators... yet.

Which system should you try to retrofit?

Really, I can't answer that for you. Again, you have to determine your goals.
What is the shape of your hull that you'll be installing the system on?
Do you want adjustability?
Do you want it automated?
Is cost of the project a big factor?
Are you okay with something permanent?
Do you want quick side to side changeovers?
Do you want something that doesn't require being taken off and stowed when not in use?
How handy are you at fabrication?


Swim platform effects
I'll briefly touch on the effects of swim platform on the surf wave. In short, if your platform is dragging in the surf wave as it comes off the back of your hull, that's typically bad. The worst is when you have a fiberglass platform with a big lip that's cutting into the wave. This will typically rob the wave of power and make it less clean.

The solution is simple. Have a platform that is smooth on the bottom and best case scenario, NOT dragging in your wave.

If you have a teak platform, you can trim it. If you have a fiberglass platform, you'll likely just replace it. Some have made them out of teak, or wood coated in fiberglass, or out of HDPE, or even textured HDPE (Like Grip-X). the basic shape needed is a trapezoid where the corners of the platform that would ordinarily drag in the wave are cut off. (like cutting the corners off the rectangle of the platform).


I hope this article gives some overview and insight into why a surf system might be attractive and the things you need to start thinking about when deciding if and how you might put one of these on your boat.

Happy Surfing!