Go Back   Starboard Forums > Free Forum

Reply
 
Thread Tools Display Modes
Old 16th December 2009, 01:53 AM   #11
BelSkorpio
Member
 
Join Date: Jan 2009
Location: Belgium
Posts: 481
Default

Hi,

I'm just back from Sal, Cabo Verde. I saw Josh Angulo surf in Ponta Preta (you know, the PWA wave spot in february). There was about 12-13 knots of wind, offshore, also bearly no whitecaps. I passed him, fully planing, on slalom equipment ( 115L board + 8.1 rig) just behind huge waves of +3m. He was on wave equipment with a 5.7m rig (yes, that small), schlogging around just behind the waves. Now Josh is quite a bit heavier than me. You should see him when he catches one of those giant waves. I don't understand how he does it. It almost seems that the rig is of no importance anymore. Unbelievable how he rides those waves. I guess he uses all power of the waves. Damn he's good.
BelSkorpio is offline   Reply With Quote
Old 16th December 2009, 06:09 AM   #12
kiwiben
Member
 
Join Date: Dec 2009
Posts: 71
Default

sorry joe, won't happen again... promise

thanks belskorpio and the guy before, i am fast coming to the conclusion that, unbelievable as it may seem, there are windsurfers out there who are actually more talented than me... a bit of a bombshell...

Your whitecap comments all make sense. A little duckpond can be in 30 knots and have no whitecaps.

On the contrary too, sometimes "Whitecap speak with forked tongue." Sometimes I drive up to a spot, see tons of whitecaps and get ultra aroused instantly, erecting my most manly rig as fast as humanly possible and sprinting into the water. My arousal is quickly deflated when i find myself slogging submarinally at half a knot in wind of about 8 knots... bummer dude...
kiwiben is offline   Reply With Quote
Old 17th December 2009, 12:04 AM   #13
carlosgp5
Member
 
Join Date: Dec 2008
Location: SC
Posts: 61
Default

From the beaufort scale, from 7 to 10 knots, one should start to see whitecaps...
What I think is that it depends on the distance that the wind is running on the water surface. Lets say, off-shore 10 knots: no whitecaps close to shore, but if you go 1 mile out, youre gonna see them; Now if you have an on-shore of 10 knots, itīll be coming from far of the coast, and there will be a lot of it...
Also, the state of the water will depend on how much time the wind has been blowing for; half an hour of 6 knots on shore, no whitecaps. 6 knots blowing for 2 hours, sure you will see it.
carlosgp5 is offline   Reply With Quote
Old 17th December 2009, 01:40 AM   #14
Ken
Member
 
Join Date: Aug 2006
Location: Dallas, Texas USA
Posts: 799
Default

After seeing carlosgp5's post, I looked a little deeper. It seems that all the "white cap" formation information on the web is based on the Beaufort scale and they all say that at Force 3 (7-10 knots), white caps begin to form. I don't know if it is at the bottom or top end of the range, but if there is a specific wind speed in knots where caps begin to form, it would be good to know. I have always used the 10 knot rule, but if caps form in less than 10 knots, it would be interesting to know the exact wind speed.
__________________
Toys:
Formula 160; iSonic 111; HiFly Move 105; Tiga 263; '85 Mistral Superlight.
Maui Sails TR 11.0; 9.2; 8.4; 7.6; 6.6; Maui Sails Switch 6.0; 5.2; Maui Sails Global 4.5; 4.0.
Ken is offline   Reply With Quote
Old 17th December 2009, 05:30 PM   #15
Farlo
Member
 
Join Date: Aug 2006
Posts: 531
Default

Hi Ken, most probably it can't be related to a single factor (i.e. windspeed). You won't see whitecaps on a speed canal even with 50 Knts blowing. There are no whitecaps when there are no caps (not enough wave height). I guess time, temperature, density, water length & depth... play a role as well.
Farlo is offline   Reply With Quote
Old 17th December 2009, 08:56 PM   #16
Unregistered
Guest
 
Posts: n/a
Default

Like said before (Jean Marc / SKorpio) what you can do in waves breaking on a reef, is slog around the waves to the back of the waves and then use the wave to get planing. Start with leaning forward like surfers do. With hardly any pressure in the sail. You need waves breaking on a reef so you also have a nice quite part which you can use to get out there. In places like Sylt it would be almost impossible.
  Reply With Quote
Old 17th December 2009, 09:15 PM   #17
Ken
Member
 
Join Date: Aug 2006
Location: Dallas, Texas USA
Posts: 799
Default

Farlo,

I agree that there are several factors that play a roll in developing white caps, but if you look at all the youtube videos on speed sailing, there are plenty of white caps in the speed canals that pop up with only a couple of meters of fetch. The canals are filled with caps. Exactly my point in my first post. Wavelets can cap even if only a few centimeters high.

The video below is an example. While this isn't a canal, it shows how little fetch is necessary for caps to form if there is enough wind. However, I doubt that there would be caps along the shoreline if the wind was 10 knots, but they will form, the only question is how much fetch is necessary to create caps in 10 knots.

http://www.youtube.com/watch?v=aWyzkZFy7HI&NR=1
__________________
Toys:
Formula 160; iSonic 111; HiFly Move 105; Tiga 263; '85 Mistral Superlight.
Maui Sails TR 11.0; 9.2; 8.4; 7.6; 6.6; Maui Sails Switch 6.0; 5.2; Maui Sails Global 4.5; 4.0.
Ken is offline   Reply With Quote
Old 17th December 2009, 10:52 PM   #18
Farlo
Member
 
Join Date: Aug 2006
Posts: 531
Default

Hi Ken, in this one whitecaps are much less noticeable: http://www.youtube.com/watch?v=ugBXkpfHw7o&NR=1
Another factor that may play a role is sunlight. Sometimes you see plenty of whitecaps, then there is a cloud coming and all of a sudden you see much less. (Of course whitecaps are still there, but if this can trick your eyes, it will more surely trick photos or videos). Anyway I remember sunny days with strong offshore wind, certainly more than 10 Knts, and no whitecaps even 100 meters away from the beach. Could very well be that the necessary fetch for 10 Knts to blow whitecaps is several hundred meters, as Carlosgp5 suggests. Anyone with some model?

Last edited by Farlo; 19th December 2009 at 03:43 AM.
Farlo is offline   Reply With Quote
Old 18th December 2009, 02:47 AM   #19
Jean-Marc
TEAM
 
Join Date: Aug 2006
Posts: 1,359
Default

Interesting discussion going on here...!

For basic ocean wave formation, please check fluid dynamics theory at http://en.wikipedia.org/wiki/Ocean_surface_wave.

Breaking waves appearing in the form of whitecaps over the sea surface is a wind-driven feature that occurs at a wind speed greater than about 4 m/s (> 8 knots or > 3.5 Bft). Below that wind speed, whitecaps are simply not observed.

Whitecap coverage of sea surface is proportional to both wind duration and fetch.

As wind blows over the sea surface greater than about 4 m/s, a "whitecap" of bubbles and streaks is created on the breaking crest of an ocean surface wave. Whitecaps are formed when large numbers of bubbles produced by a wave rise to the surface, and the bright white area of a whitecap arises from multiple light scattering by elements of size comparable to or greater than the wavelength of visible light. These elements are clusters of proximate, closely packed bubbles at or near the surface of the breaking crest of an ocean surface wave (source http://www.springerlink.com/content/j0647331h845710t/).

So to answer the initial question, yes, it is possible to start and sustain the planing in the absence of clearly visible whitecaps. Formula can do that as of 6-7 knots of wind speed. However, it is impossible to start and sustain the planing as of 4 knots of wind with any type of windsurfing gear, except when the forward motion is provided by the power of a wave pushing the surfing hull down the line.

Cheers !

JM

Last edited by Jean-Marc; 18th December 2009 at 03:06 AM.
Jean-Marc is offline   Reply With Quote
Old 18th December 2009, 09:33 PM   #20
vikingsail
Member
 
Join Date: Apr 2007
Location: Adirondacks, NY, USA
Posts: 27
Smile

There is one other consideration why you may not see whitecaps on photographs or videos. If the photographer is upwind from the sailor the whitecaps are on the backside of the waves; they're hiding. Remember the rule onshore winds rig larger then the water appears, offshore winds rig smaller.
__________________
F2 Max2Air/Madd135 Powerex Masts
Tuning Tech for Sailworks/Roger Jackson
Club website:
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
vikingsail is offline   Reply With Quote
Reply

Bookmarks

Tags
None

Thread Tools
Display Modes

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Instability while planing Roly Gardner Windsurfing School 6 24th March 2008 04:49 AM
First Time Planing! Roly Gardner Windsurfing School 6 17th July 2007 04:47 AM
Earliest planing with 8.5 m2 Per Free Forum 12 14th May 2007 01:15 AM
Phantom 320 planing?? Per Free Forum 5 19th April 2007 08:35 PM
Go 180 Planing... Clean! SurfSerf Free Forum 1 10th March 2007 02:15 AM


All times are GMT +7. The time now is 03:03 PM.