wake tuning

[Myoung42]

I've done a bit of reading on wakeboard boat manufacturers' websites, where they talk about engineering or tuning the wake for shape and crispness (typical boats are ~20'-24' LOA and are v drive or inboard). Seems like they may guard design resources pretty tightly since I haven't been able to find anything on the subject.

Anyone have any papers, books, or tribal knowledge on the subject?

Thanks

[messabout]

Are you confident that wave forms can be custom arranged to suit a particular application? The advertisers may claim some sort of sorcery like this but that does not make it so.

I suspect that the shape of a wake changes in proportion to the distance from the boat. If a wakeboarder can adjust the length of the tow line he can probably get to experiment with a number of different waves, all from the same boat.

[nautique210]

Hey mark, Most wake boat mfg market a small trim tab that they say cleans up the wake. Just gimmicks to sell to people who don't know much about wakeboarding. Malibu's wedge hydrofoil does steepen the wake but does not make it bigger. The only way to make the wake bigger is to add lots of ballast and as messabout says depending on the line length, speed and ballast will dictate the wake. Generally wide beam = rampy wake, narrow beam = steep and firm wake. The wider boats need a lot of weight to get the wake up but I personally prefer a rampy wake, as long as it's big

As for the hull design, doesn't look like anything really tricky. I suppose the biggest problem is to get them to turn properly fully loaded as they love to chine lock.

Cheers, Shaun

[Myoung42]

Thanks to both of you for your input!

Shaun - ok, the weight and beam portion of your reply make sense. Seems like the hull design would determine the crispness of the wake (foamy or crisp). What do you mean by "chine lock?"

[nautique210]

Chine lock tends to happen when turning reasonably hard. The boat wants to lay over and seems to get stuck on the chine. The result is a boat that will not continue to turn and normally results in the need for some serious reverse gear depending why u are turning.

Back to the hull design, if you compare the 3 most 'hard core' wake boats, Malibu VLX, Mastercraft X-Star & Nautique 230 the hulls look really different. The Mastercraft & Nautique's running surface taper off in width significantly at the transom (The Malibu's doesn't). I've heard that it's to get the stern deeper thus making the wake bigger but I can't see it plus I don't know enough about it. Cos the Malibu doesn't taper off much at all and the wake is really good. The MC has all sorts of steps and strakes going on but the Nautique dosent, it does have a lot more deadrise though. Not a topic that gets much discussion on these boards. I suppose wake boats are the pigs of the water and most other boaters hate them.

So why the interest? Do you wakeboard? or designing / building a wake boat?

[das boot]

all fudge, these guys are right, the salesmen make non naval architects believe that this is the case but I'm sure the wake created by the boat is at the bottom of the list when it comes to the hull design.

[Doug Lord]

This may be of some interest-check out the electrically controlled ballast tanks and "wake plate":
http://wakeboardingmag.com/boats/200...zo-sv220-2008/

[jonr]

It is funny that after so many years of flattening the wake for slalom skiers, they are now making it bigger.
-- '93 Nautique

[Myoung42]

Originally Posted by nautique210

Chine lock tends to happen when turning reasonably hard. The boat wants to lay over and seems to get stuck on the chine. The result is a boat that will not continue to turn and normally results in the need for some serious reverse gear depending why u are turning.

Back to the hull design, if you compare the 3 most 'hard core' wake boats, Malibu VLX, Mastercraft X-Star & Nautique 230 the hulls look really different. The Mastercraft & Nautique's running surface taper off in width significantly at the transom (The Malibu's doesn't). I've heard that it's to get the stern deeper thus making the wake bigger but I can't see it plus I don't know enough about it. Cos the Malibu doesn't taper off much at all and the wake is really good. The MC has all sorts of steps and strakes going on but the Nautique dosent, it does have a lot more deadrise though. Not a topic that gets much discussion on these boards. I suppose wake boats are the pigs of the water and most other boaters hate them.

So why the interest? Do you wakeboard? or designing / building a wake boat?

Shaun - thanks for all the input. Yes, I am a pig of the water, but I've never had much chance to ride behind a "real" wakeboat, so the input is very much appreciated.

And yes, I am interested in designing/building a boat that can be used as a family day boat, but is optimized for wakeboarding, similar to the mastercraft wakeboard boats. Beautiful form with well thought out function and quality construction. I love the look of wood boats like the Susan C by Van dam, but I haven't seen any plans that really fit how I want to use the boat, so I'm slowly working up a design of my own that I plan to build...when the time is right.

I became an engineer because I love engineering, but as it turns out I don't get to do much real engineering at work (let's not use the "w" word more than once here). Boat design is an escape that keeps me sane. I'm not in any hurry. I'm not looking to save money or make money. It's just something I enjoy. So I'm here to learn from those who know.

[Zoe]

I just came across this thread and I was hoping someone might help me out. I am writing an article on planing and need someone to interview. Questions would be about hull shape for ease of planing and wake shape.

[rxcomposite]

Originally Posted by jonr

It is funny that after so many years of flattening the wake for slalom skiers, they are now making it bigger.
-- '93 Nautique

In wakeboarding, you need to create large wave so the wakeborder can jump over the waves. The bigger the waves the better. The boats are designed so that the transom sits deep in the water, thus throwing a big wave.

[Leo Lazauskas]

Michlet (specifically Godzilla) can be used to find a hull (or hulls) that make a user-specified wave pattern.

Mr. rxcomposite pointed out that wave wake-generating boats have deeply-immersed transom sterns to create a large (transverse) wave. That's a bit of a problem for Michlet (and most computer codes) because the flow behind a large transom stern is poorly understood.
However, you still might be able to get some ideas by trying out different hulls and seeing what wave wakes they make. The predicted height of the waves might be inaccurate if you use stubby hulls, but the shape of the wave-wake should be reasonable.

Steven Schmied, working with people at the Australian Maritime College, has been developing an idea for a circular wave pool. He began by using Michlet but, as I warned him, it is not appropriate for that type of application. His work with other computer codes and some experimental work is available on the net.

There are also several videos of his wavepool concepts on YouTube.
Although they are not directly related to your work they might provide some inspiration:
http://www.youtube.com/watch?v=6Ud_h...eature=related
http://www.youtube.com/watch?v=tdv0_...eature=related

Good luck!
Leo.

[rxcomposite]

Hi Leo,

I am attaching a copy of what we researched several years ago. This came from Sorensen's Guide to Powerboat. The book says about loading the stern with ballast. Another suggestion is to use an adjustable foils to keep the stern down.

It appears to be fairly flat bottom boat riding bow up, inefficient trim and throwing a lot of wake.

[Leo Lazauskas]

Originally Posted by rxcomposite

Hi Leo,

I am attaching a copy of what we researched several years ago. This came from Sorensen's Guide to Powerboat. The book says about loading the stern with ballast. Another suggestion is to use an adjustable foils to keep the stern down.

It appears to be fairly flat bottom boat riding bow up, inefficient trim and throwing a lot of wake.

Thanks, rx.
It really is a strange sort of optimisation/search problem.
You want large waves, with the right shape and in the right place, while also trying to keep the total drag reasonable in order to reduce fuel costs.

I prefer the simpler (but very interesting) inverse problem - given a wave wake, what hull or hulls made it?

Leo.

[rxcomposite]

Myyoung42,

I seem to remember there is one engineer who studied bow waves and his first model was a barge with a "swim bow" (straight flat bow) that threw a lot of wake. I will try to search for the copy. He has some mathematics in his paper. I know there were other heavy research with a lot of math but it is about bulbous bow. Could be related.

Leo could be of help as he is a very good researcher and can understand the math involved.