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How Fast Wavesailing?
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beallmd



Joined: 10 May 1998
Posts: 1074

PostPosted: Sat Jul 21, 2012 12:59 pm    Post subject: How Fast Wavesailing? Reply with quote

At our brown pond, Washoe Mud Hole State Park, there is a fascination with "going fast." Some folks have GPS units to measure and record their speeds (up to around 35 MPH-very impressive really). Others talk about a certain board, sometimes older boards, known for their speed e.g. F2 Sputnik. As I became ever more interested in wavesailing I became more interested in how SLOW one sails in and around waves. Maybe you've thought about how slow one can "sail" as well.
Waves are all about postioning. Being in the right place at the right time takes priority over everything else. One goes outside, where there is more wind, to get up wind and get into the lineup for your wave. Going upwind as much as possible may involve sailing fast but more often one foregoes speed for getting farther upwind.
Then when riding waves the wave provides much of the energy rather than the wind. Going downhill on the waveface provides acceleration that one can easily detect in windsurfing and surfing that is obvious. So, how fast are waves? How fast do we sail around and on waves?
In my research I found someone who addressed a fascinating question, how fast are we going when we start to plane? (Not how low is the threshold wind for planing-an altogether different question.) The answer appaers to be right around 10 knots or 11.5 MPH. http://www.seabreeze.com.au/forums/Windsurfing/Gps/Planning/
How fast do waves travel? I'll forego the physics discussion (I'd probably blow it anyway) and simply answer that small foot washers may travel as slow as 10 MPH. At the other extreme, Jaws is said to travel at up to 35 MPH. I read sometime ago that the waves us mere mortals sail are around 18 MPH, that should be a good estimate.
All of us who have even tried a little wavesailing know that we can easily outrun waves. We can easily catch a wave from behind and have to slow down to actually ride the wave. Most estimates that I've read are that "normal sailing" is in the 22 to, say, 28 MPH in short bursts, probably not much more than that. The article on Jaws waves said that riders of Jaws probably reach speeds of around 55 MPH taking the drop down the face. So if we're riding an 18 MPH wave and take the drop (not anywhere near the drop at Jaws or Pipeline or Waimea etc.) then we might reach a burst speed of a little over 28 MPH.
Finally, in positioning for waves, I have learned to stall relative to the wave speed while waiting for the wave once I'm in the right position relative to the breaking section. I do this by pinching upwind hard and keeping it just on the edge of planing, I'm guessing something around 15 MPH. One may slow down going straight ahead to wait for the wave, usually you don't go downwind as it isn't necessary to overtake the wave in front.
Another thing that I see commonly and I've learned to do is to "take the drop," accelerating down the face, and then gybe in the flat area in front of the wave, mostly using the speed of that drop to take one into the gybe. Again, probably in the 28 MPH range.

Note; I would accept that some of the older boards are at least as fast as the modern boards. The modern boards are shorter and wider, and I think there would no debate that they turn much easier and readily. I believe we may have given up some top end speed for a more fun and playful board. These boards may allow us to play with chop and swells more and do tricks, if you do tricks. Also, the newer boards may actually allow us to sail more slowly while still having an active board under foot. Just my thoughts; I'm not not sure about this though.



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zirtaeb



Joined: 03 Jul 2009
Posts: 2407

PostPosted: Sat Jul 21, 2012 1:45 pm    Post subject: Reply with quote

Shoulder high waves, or what most folks call "logo" high, travel around 12 mph as it hits the shallower waters and humps into a wave. Twas moving maybe 18 in waters deeper than 15'.
Since you drop down the wave after u catch it, you must be going 19+.
DTL, on a wave face like CaboVerde, easy 30 mph.
Upwind, going left like mostly Waddell, maybe 16mph.
Stalled at the bottom, waiting for the wave to crash behind you, maybe 8mph.
As you say, bigger waves move faster, smaller waves move slower.
"Mast high" waves usually equate to about 8-10' in surfer terms, because ofthe ANGLE the photo was taken....the higher up, the bigger the wave appears to be.
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keycocker



Joined: 10 Jul 2005
Posts: 3456

PostPosted: Sat Jul 21, 2012 2:31 pm    Post subject: Reply with quote

We have learned to stall and chat with a person in the water, heading downwind a few feet to surface the board and repeat. Quick tack if you get 30 ft away.
Same technique most use to await a wave. Doing this in flatter water just to chat, it becomes obvious you are going 0 to 2 knots since you stay with a swimmer going zero.

I work as a volunteer in Speed events. The older boards are still fast but these guys like Eric Beale use new wider boards instead of the older needles and Thommens they set world records on in their garages.
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beallmd



Joined: 10 May 1998
Posts: 1074

PostPosted: Sat Jul 21, 2012 2:35 pm    Post subject: Reply with quote

Don't disagree with above, altho might revise it up a little. Some facts; Tsunami waves can travel up to 500 MPH in the open ocean.
Open ocean swells from wind are said to travel in the 5 to 60 MPH range.
Waves, as they hit a shallow beach or reef, will halve their open water speed. The estimate for Jaws was that it breaks at 35 MPH, so its open water speed would have been about double that, 70 MPH, which is about the upper limit for an open ocean swell-all makes sense as these are some of the biggest waves seen.
The figure of 18 MPH for windsurfing waves of a moderate height makes sense when one considers that waves of just over 10 MPH would be below planing levels and that one needs to slow down a little to catch the wave; I.E. from 22 MPH to 18-just seems correct to me.
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keycocker



Joined: 10 Jul 2005
Posts: 3456

PostPosted: Sat Jul 21, 2012 2:37 pm    Post subject: Reply with quote

thanks for the post. interesting stuff
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chophop



Joined: 16 Apr 1996
Posts: 190

PostPosted: Sat Jul 21, 2012 4:03 pm    Post subject: Reply with quote

I have read that the speed of a swell train is directly related to it's period. That a swell train travels at 1.5 times the period in open water. So a 17 second swell train is moving at about 25.5.knots (17 x 1.5 = 25.5).
That is open water.

The same article specified that each swell in the train actually travels at twice the speed of the train and each swell moves along like a conveyor belt working its way up to the front of the set then losing energy and falling off to the rear.

I doubt that the waves breaking at Jaws have lost half of their speed when they break. Since they are hitting a reef way off shore and just kind of breaking really pretty fast; nothing to slow them down before that reef.
Areally big 22 second swell train would be cooking along at 33 knots, maybe going 25 knt or better as they jack up on the reef and the rider of course could easily hit 45 knt or about 50 mph as he hurtles down the huge face Smile
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chophop



Joined: 16 Apr 1996
Posts: 190

PostPosted: Sat Jul 21, 2012 4:04 pm    Post subject: Reply with quote

I have read that the speed of a swell train is directly related to it's period. That a swell train travels at 1.5 times the period in open water. So a 17 second swell train is moving at about 25.5.knots (17 x 1.5 = 25.5).
That is open water.

The same article specified that each swell in the train actually travels at twice the speed of the train and each swell moves along like a conveyor belt working its way up to the front of the set then losing energy and falling off to the rear.

I doubt that the waves breaking at Jaws have lost half of their speed when they break. Since they are hitting a reef way off shore and just kind of breaking really pretty fast; nothing to slow them down before that reef.
Areally big 22 second swell train would be cooking along at 33 knots, maybe going 25 knt or better as they jack up on the reef and the rider of course could easily hit 45 knt or about 50 mph as he hurtles down the huge face Smile
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mac



Joined: 07 Mar 1999
Posts: 5356

PostPosted: Sat Jul 21, 2012 4:20 pm    Post subject: Reply with quote

Right you are chophop. Here is the equation:

As waves pass some fixed point, the time between consecutive crests is the wave period T. The speed of the wave, or its celerity, C, (as ocean engineers refer to it), is the distance travelled by a crest per unit time, or



C = L/T Equation 1

C is speed, L is length, T is time. Had to look it up, I studied this a long time ago: http://scubageek.com/articles/wwwceler.html
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zirtaeb



Joined: 03 Jul 2009
Posts: 2407

PostPosted: Sat Jul 21, 2012 7:23 pm    Post subject: Reply with quote

Unfortunately, the "40-50" number is well beyond possibility.
On a 27' Wiamea wave, or Mavericks, the boards ridden there can barely exceed 28 mph no matter how it's propulsed, except for towing.
A average 10' full "GUN" board has tons of tail rocker, has soft rails in the tail, has a low aspect thick draggy fin or fins, and when used as a windsurfer, is about the slowest of possible freeride, slalom, or even bump n jump boards. Maybe faster than freestyle boards, but just barely.
The rider dropping down the wave is going as fast as he can ever, and if you watch how slowly one actually drops in at the big wave spots, you'd estimate barely over 28mph max.
I've ridden Wiamea, have used 3 of my guns for windsurfing, and built over 5 boards for bigger waves, and none nearly as fast as a '80's slalom board.
Speed is not necessary in a big wave board. CONTROL in the bumps and backwash is the key, and the length for wave catching, of course.
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outcast



Joined: 04 May 2004
Posts: 2406

PostPosted: Sat Jul 21, 2012 9:16 pm    Post subject: Reply with quote

I dunno how fast, but check out 1:30 in the vid
Race Track fast

http://www.continentseven.com/2012/07/18/minds-wide-open-dvd-additional-footage-kauli-seadi-at-cape-verde/

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