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Old    Show (bigshow)      Join Date: Feb 2005       06-18-2006, 9:45 AM Reply   
Here's some follow up on the Wake Experiment #4 with what I'm calling the Surf Switch.

Here is a set of photographs comparing my regular-port wake against the Surf Switch enhanced wake. Note the Surf Switch wake was losing ballast during this test. Regular Baseline photos are marked in the upper-left hand corner with RB and Surf Switch photos are marked with C8 in the upper left hand corner. The speed in mph is marked in the upper right-hand corner. Note that Perfect pass is under reporting speed by 10% to 20%, i.e. speed is faster than marked. See a larger photo here: http://www.wakesurf.net/media/showphoto.php?photo=191&cat=500&ppuser=27

Some observations:
For speeds above 9 mph the face of the wake is cleaner Ė less white foam.
For speeds 9 mph through 11 mph on the RB photos you can see a middle wake feature made by the hull extension that makes the wake curl early.
For speeds at 9 mph to 11 mph the formation of foam at the end of the wake starts further back on C8 than RB.
For speed for 12 mph and above the formation of the foam at the tail of the wake starts about at the same place but the shape is different.
For speeds 10 mph and 11 mph the RB rooster tail is large and vertical.

I can see thereís a difference in wake shape, but more work needs to be done to ďdial inĒ a Surf Switch wake. The rooster tail formation needs to be looked at as well.
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Old    Jeff Walker (surfdad)      Join Date: Sep 2004       06-19-2006, 9:29 AM Reply   
Hey Ed, nice comparison, but I'm a little bewildered. Recreationally speaking, is there a big market for creating a wake that folks can surf at 13 mph? That wake looks the best. I toss a pretty big wake and have difficulty riding Dennis' 6'2" long 25" wide and 2.75" thick board at 12 mph. 11 mph is doable and fun, but the surf switch seems to throw an impossibly ugly spray on the spine at 10 to 11 mph negating almost any trick except cruising in the pocket. Is that what you are finding?
Old    Show (bigshow)      Join Date: Feb 2005       06-19-2006, 9:56 AM Reply   
Jeff,

I selected speed ranges from too slow to too fast, to make sure I capture and bound the response of the Surf Switch. I donít think 13 mph is a surfable speed, not for me anyway.

As you say the spray is pretty ugly, at 11 mph itís bad, even worse in some configurations. I actually get some spray in my face when I run with out the Surf Switch, very distracting. I think I said in my first post, the Experiment #4 one that the technique had merit, but it also needs some work.

One thing that I think I could say early is that the Surf Switch can be set to tweak a wake, much like some are using a wake plate to tweak a wakeboarding wake. For instance a low setting could partly equalize Port and Starboard wakes. However I think thereís a lot more potential than minor wake tweaking.

Iíve only tested the Surf Switch once, and probably wonít get a chance to test again this week. I think I need to try a handful of ďdialing in setup to see what can be done about the plume. So this is NOT a ready to rock concept, one that needs work.

Input from the online community helps confirm my observations.

Thanks!
Old    Jeff Walker (surfdad)      Join Date: Sep 2004       06-19-2006, 10:23 AM Reply   
I'm not sure it's possible, but...something I'd REALLY like to see is a barrel. In your testinh have you seen ANYTHING that enhances the curl at the back of the wake? I'm not sure I'm being clear, but imagine a workable pocket and then at the back a curl large enough that a rider could slip in to the tube. LOL - I just got an image of a boat manufacturer offering the "new Enzo Pipeline" :-)

Anything like that?
Old    Show (bigshow)      Join Date: Feb 2005       06-19-2006, 10:51 AM Reply   
I took data on 13 configurations and a 14th set as a baseline, which took an entire evening. Iíd say that in my observations Iíve first seen a fairly messy wake face clean up dramatically, second and unfortunately have seen a plume develop at certain speeds, third have seen the white foam move further back on the wake, and fourth have seen the Starboard wake also clean up nicely.

In my normal setup I have to put a lot of weight in the bow to get a decent wake. With the Surf Switch in play I think that I should be able to move weight further back. What will happen with the weight further back, I donít but I canít wait to see.

I really think Iím hull limited in my experiments, the gunnels are too low and the hull shape is ski not wake specific. Just this weekend when the boat traffic was very busy a wave washed over my port gunnels right at the back of seating, probably took on 3 to 5 gallons Ė kind of freaked me out. It would be interesting to try this modification on another boat but I think I need to protect the idea first.

Whatís the famous pipeline in Oahu?
Old    Jeff Walker (surfdad)      Join Date: Sep 2004       06-19-2006, 2:44 PM Reply   
Pipeline is part of the onsite improvements in a new housing tract :-) Also there is one in Alaska that heads down to the lower 48. :-)

Ed, have we ever talked about wake formation? The principal mechanism in the ocean is wind - wind over the ocean transfers some energy and then the shoreline or reef or something else creates the break.

Behind the boat it's the hull of the boat dragging through the water - or more importantly forcing sections of the water to flow faster around the hull. If I'm not mistaken, the trough of the wake is the fastest section of water flow and the peak or the lip is the slowest. Is there some mechanism that could affect changes in this flow without requiring,- what REALLY seems to me to be almost medevial technically, dragging tons of weight through the water? It would seem to me that something could be attached in an outrigger manner that wouldn't require 3 foot high gunnels or the stresses of slogging a hull through the water - or is it more a pipe dream? :-)
Old    Show (bigshow)      Join Date: Feb 2005       06-19-2006, 8:03 PM Reply   
I thought that both wind and the gravitation al pull of the moon provided the energy for ocean waves. At least the tide is driven by the moon. The shape of the shoreline has an effect on the development of wave reaching the shore, west coast guys know that better than a flat lander like me. I think that a long slow slope makes a better ocean surfing wake, right?

The speed of the water on the surface of the ocean is faster than the bottom, right? The same is true for the current in a river; the current at the top center of a river is faster than the bottom and the shore.

As for an alternative less crude method, maybe the Switch Blade is the real deal, pushing high speed thrust where it does the most good? On the other hand I think the Inland Surfer guys are going pure with ballast and no Switch Blade, some times crude but simple is best.

Youíre asking some good but difficult questions. Iíll have to think about it a bit more before saying something that might be unfounded.

I almost want to sell my boat and buy an old beater to experiment with.
Old    Jeff Walker (surfdad)      Join Date: Sep 2004       06-20-2006, 7:30 AM Reply   
My "understanding" about how ocean surface waves are formed is that wind creates it, not the moon's gravitational pull...uuummm, someone once explained to me that it isn't a flow of water like a river, it's an up and down movement that BREAKS when it reaches shallower depths.

http://en.wikipedia.org/wiki/Ocean_surface_wave#How_Waves_are_Formed

I am NO expert, however.

Ed, my understanding of boat wakes is that the bow and draft are what cause the size of the wake. So a BLUNT bow and a DEEP draft will cause a larger wake...conversely, a POINTED bow and PLANNING hull would create a smaller wake. Have you done any experiment with increasing the width of the bow? We've all fiddled with creating a deeper draft through ballast. I'm just wondering if we could affect a larger wake from the other end of the boat? :-)
Old    Show (bigshow)      Join Date: Feb 2005       06-20-2006, 8:07 AM Reply   
Wikpedia is often a helpful starting place, Iíll have to read it in more depth this evening and maybe find a few other references. Iíve previously research waves for wakeboard wake generation, http://www.madsci.org/posts/archives/jul2001/994688283.Ph.r.html and in an effort to prepare a defense for protecting wakeboarding on our local hot spot. Thereís a paper by Steve A. Hughes Titled ďWave momentum flux parameter: a description or nearshore wavesĒ that Iíve looked at but itís been a while.

I get out of the flat lands to the Atlantic once every two to three years, so I have had some opportunity to see ocean waves but havenít ever really studied them with wake surfing in mind. I thought the waves coming in as the tide was rising might be different from those when the tied is falling.

The reference to rivers is only to set or confirm a range differing speeds at various conditions. The speed of moving water is slower at river shore line, bottom of a river, and at the bottom of the ocean shore where waves develop and at the surface.

So do you remember in a past post when I was asking about the 1960s John boats used I think in Cypress Gardens wakesurfing demonstrations? There are two kinds of Aluminum fishing boat shapes that come to mind, the pointed V type and the squared off John boat type. If your right that a boat with blunt front end makes a good surf wake maybe we can trade in our high dollar fiberglass boats for cheaper John boats. I saw a 24 foot john boat at the boat show last winter.

I havenít seen an Enzo up close. The Enzo bow area looks expanded - wide, I thought for creature room, maybe itís wide to blunt the nose as you suggest. If that weíre the case then wouldnít the pickle fork X-Star also make a good wakesurf boat? I donít think that Iíve heard good wake surfing reports for the pickle fork X-star, someone post a picture and provide some evidence one way or the other. Actually I think I read on WW that someone used an X-Star at a wakesurf comp and the goofy wake was poor and they didnít have a plan B.
Old    Jeff Walker (surfdad)      Join Date: Sep 2004       06-20-2006, 8:23 AM Reply   
I've heard the problem with the X-star is that weird box in the back, it wrecks the wakesurfing wake. It's got a ton of space for adding ballast too, so it's too bad. I've ridden behind an X-star and it really isn't pretty. I think that the Enzo is WIDE towards the bow...with a more abrupt curve and the very TIP of the bow is straight at the deck, right? But, at wakesurfing speed the part of the hull that is PLOWING through the water is lower and further back towards the transom...I'd guess that is what we'd need to look at, what part of the hull is first contacting the water. I can't imagine that a STRAIGHT bow like a Jon boat would work well and wouldn't the sides of the boat still need to flair outward to create the best wake?
Old    Show (bigshow)      Join Date: Feb 2005       06-20-2006, 9:49 AM Reply   
So would you say the block in the back is a hull extension, like on my lightning? I'm pretty sure that's not good for building surf wakes.

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Old    Jeff Walker (surfdad)      Join Date: Sep 2004       06-21-2006, 12:06 PM Reply   
That's it, exactly. In my experience, it trashes the wakesurfing wake on the X-star.

Ed, check this article and the section I have Cut'n pasted:

http://www.oceansonline.com/waves.htm

The second result is that as a wave feels bottom, it begins to slow down. And since the bottom of the wave is feeling bottom first, it is the bottom of the wave that slows down first. The water particles at the bottom of the wave can no longer complete their circular orbits, so the orbits become more elongated and elliptical. However, the water particles at the top of the wave are still going like gang-busters and are moving faster than the water particles at the bottom.

The net result is that the wave starts to peak and get stretched out at the same time. Eventually, the wave peaks so high that it can no longer keep its shape and the stretching surface water particles orbit faster at the top than the wave is moving forward at the bottom, and the entire wave pitches forward and breaks. After a journey of thousands of miles, the wave meets its final destiny on the shore and spills its energy onto the beach. If it's lucky, it's short 5-6 day life span will be remembered as a short 2-3 second burst of exhilaration in the mind of some passing surfer who happened to hitch a ride.

In the article it refers to an area of NO MOTION that is exactly 1/2 the wavelength. I wonder what would happen if you could measure that wavelength and then drive the boat in water that was exactly that depth? Would it maximize the height of the wave? If that was the case, could you artificially create a bottom by dragging something under water?
Old    Show (bigshow)      Join Date: Feb 2005       06-21-2006, 12:32 PM Reply   
I was busy doing related research last night so I didn't do my reading, but I think that the above text provides a good visual (mental)picture.

The ocean is different in that there is a period between waves. Behind a boat youíre making a leading wake that is followed by other trailing wakes. Can you use that period from leading to trailing wave to figure out the wave length? You'd need to know the angle of incidence and peak to peak interval.

I'd say that the water at the bottom of your lake probably isn't moving much. Tribal wakesurf knowledge says that depth over 20 feet doesn't help the wake, but 10 to 5 feet can contribute to a poor surf wake. So while wakesurfing a 10 foot deep lake starts to have an impact on the circles or ellipses, I guess? If your lake is 20 feet or deeper I think you probably get motionless bottom for free.

There's probably a single event case like a tsunami that would be interesting to consider. For now you're ahead of where I'm at.
Old    Dennis (dennish)      Join Date: May 2005       06-21-2006, 12:34 PM Reply   
Jeff,
We know that shallow water effects wake size. How deep would the artificial bottom have to be?
Old    Jeff Walker (surfdad)      Join Date: Sep 2004       06-21-2006, 12:52 PM Reply   
Hey Dennis,

In that article it refers to wavelength as the distance between the waves peaks. Then goes on to say that the point of no motion is exactly 1/2 that distance. I would THINK that the distance between the first and second "roller" created by a boat would be analagous to this wave length. You're right Dennis we saw the effect on wave height at Villa Lagos, but did you notice...at times the wake was MONSTEROUSLY high. Check this pisture of Raequel Hoffman...that's huge and well formed - my "thought" or theory is that this section of the lake is at the PERFECT depth for that boat, as weighted.
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Old    Jeff Walker (surfdad)      Join Date: Sep 2004       06-21-2006, 1:22 PM Reply   
Ed, in the picture above, that lake is on average 8.5 feet deep (I do believe), but as you can see in the picture, at TIMES the wake was perfect. Now this is a Natique also, not usually know for it's wakesurfing wake. I'm just theorizing that wave height is maximized by having a point of no motion that is exactly associated with some bottom structure (real or artifical). Also that an arbitrary bottom depth isn't THE factor in make or break wake development, that it's this point of no motion that is the REAL DEAL and that will be different dependent "possibly" on wavelength. I'm wanting to try surfing in some shallower water to see if there is a change in the wave height.
Old    Dennis (dennish)      Join Date: May 2005       06-21-2006, 7:53 PM Reply   
Jeff,
One thing I noticed different about the wake at Villa Lagos was that the off side when weighted regular cut in sharply just past the spine. You can see it somewhat in the pic above. It was very pronounced compared to any other wake I have seen. I wonder if diverting water from the offside towards the spine would not increase the wake size. This would be similar to "The Wedge" in Newport Beach where the water coming back off the breakwater doubled the size of the wave coming in.
Old    Jeff Walker (surfdad)      Join Date: Sep 2004       06-22-2006, 5:43 AM Reply   
Just so that I am clear Dennis, you're theorizing something that would channel the white wash from the side OPPOSITE that being ridden, back in towards the spine?

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