wake tuning

[rxcomposite]

Originally Posted by Leo Lazauskas

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.

I think in this type, fuel cost is not the problem. They pass it to the customer. But something was developed after this. There is a wakeboarding resort in the Philippines where the wakeboarder is towed by an overhead cable and the wave(s) below is/are created mechanically.

At the time we made the research, I was thinking also of efficiency but I guess I approached the problem wrong. The customer wants a boat that can be used for water skiing (fast and no wake), can be used for wakeboarding (large wake, not so fast), and can be used for parasailing (slow, wake does not matter, but pulls like a tractor). We told him you can get one but not all three.

[Ike]

Wake boat builders started with basic skiboats. First they added ballast tanks as far aft as possible to get the stern down. They also tow slower than ski boats. Skiers like speeds around 35 mph. Wakeboarders like around 20 mph. Slower with the stern down throws a bigger wake. They added a tower to attach the tow rope to. This moved the rope higher, kept it out of the water and allowed the boarder to soar higher and farther, and the tower was farther forward than a ski pylon so it moved the pivot point forward. I also think they fiddled with the bottom of the boat aft, but if you look at most wakeboats they look just like ski boats on the aft planing surface. The problem here is that skiers want a flat wake and boarders want a big wake. So how do you reconfigure a hull to throw a bigger wake?

[Leo Lazauskas]

Originally Posted by rxcomposite

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

He is also weeks away from unemployment so he doesn't do unpaid work. The selfish bastard is a "dole bludger" who has no time for anything except his own research.

[rxcomposite]

Originally Posted by Leo Lazauskas

He is also weeks away from unemployment so he doesn't do unpaid work. The selfish bastard is a "dole bludger" who has no time for anything except his own research.

Time to get paid Leo. No more freebies. You have given away one of the greatest contribution to the marine engineering world. Why, even fortune tellers charge for "professsional fees".

[Leo Lazauskas]

Originally Posted by rxcomposite

Why, even fortune tellers charge for "professsional fees".

And for similar work, too!

[rxcomposite]

Originally Posted by Ike

Wake boat builders started with basic skiboats. First they added ballast tanks as far aft as possible to get the stern down. They also tow slower than ski boats. Skiers like speeds around 35 mph. Wakeboarders like around 20 mph. Slower with the stern down throws a bigger wake. They added a tower to attach the tow rope to. This moved the rope higher, kept it out of the water and allowed the boarder to soar higher and farther, and the tower was farther forward than a ski pylon so it moved the pivot point forward. I also think they fiddled with the bottom of the boat aft, but if you look at most wakeboats they look just like ski boats on the aft planing surface. The problem here is that skiers want a flat wake and boarders want a big wake. So how do you reconfigure a hull to throw a bigger wake?

Our imagination was limited then. We were thinking of a "fast barge" with semi streamlined bow, then shift the cg one way or the other for ski/wakeboarding. The barge idea was for the parasailing. Wide deck, slow, lots of pulling power. Use automotive gearbox so we can have at least "different gear" choice. We gave up on this weird design so we said you can have one but not the three.

[rxcomposite]

Originally Posted by Leo Lazauskas

And for similar work, too!

ROTFL. I got the joke. You are deep Leo.

[Leo Lazauskas]

Originally Posted by rxcomposite

ROTFL. I got the joke.

I had to beat Ad Hoc to the punch!

[Ad Hoc]

Originally Posted by Leo Lazauskas

I had to beat Ad Hoc to the punch!

Who...me....would I???

[rxcomposite]

found the paper but I dont have a name of the author. Seems the site is The Bulbous Bow .mht and it is titled "The wedge bow and the bulbous bow"

I cannot find my papers on "bow wave height" but i know I downloaded it from the net.

[Leo Lazauskas]

Originally Posted by Ike

Wake boat builders started with basic skiboats. First they added ballast tanks as far aft as possible to get the stern down. They also tow slower than ski boats. Skiers like speeds around 35 mph. Wakeboarders like around 20 mph. Slower with the stern down throws a bigger wake. They added a tower to attach the tow rope to. This moved the rope higher, kept it out of the water and allowed the boarder to soar higher and farther, and the tower was farther forward than a ski pylon so it moved the pivot point forward. I also think they fiddled with the bottom of the boat aft, but if you look at most wakeboats they look just like ski boats on the aft planing surface. The problem here is that skiers want a flat wake and boarders want a big wake. So how do you reconfigure a hull to throw a bigger wake?

I'm really not familiar with how the boarders move around behind the boat.
Which wave do they prefer to "ride", i.e. is it the first crest behind the stern, or the 2nd, 3rd?

Leo.

[daiquiri]

Originally Posted by Leo Lazauskas

And for similar work, too!

Aaaaaaah!!!

This was a nice one, Leo!

[keysdisease]

Originally Posted by Leo Lazauskas

I'm really not familiar with how the boarders move around behind the boat.
Which wave do they prefer to "ride", i.e. is it the first crest behind the stern, or the 2nd, 3rd?

Leo.

I believe one major difference between a hard core ski boat and a wakeboard boat or a combo ski/wake boat is the drive. A ski boat will have a straight inboard drivetrain with the engine in a box forward of the transom. On wake or combo boats we typically see V Drives.

This first video is just a guy doing wake tricks, but the wake is well defined. The second is a Promotional video of a Malibu wake boat.

Steve


http://www.youtube.com/watch?v=jwaUsUY4UHY

http://www.youtube.com/watch?v=LBKZ85s6ehc