Greg Webber and frictionless fins?

[speedneedle]

Hey Jammin,

I'd like to read more of your mate's thesis...or at least the summary! Would he post it?

Agree on the speed of surfing being low, but personally have joy with a thicker foiled fin.

Josh
www.joshdowlingshape.com

[mical]

At normal speeds, the only thing that effects performance is the length of the leading edge (and area as a function of the leading edge) and to a much smaller degree, flexibility.

Always knew this, but it's got me thinking about the new super short revolution that's currently going on.

I assume that even though the boards are shorter (5'6", 5'8" etc) there's little difference in leading edge and just less nose area that doesn't have a lot of contact anyway?

[mustkillmulloway]

looking and talking with a local glasser who occasional lowers himself shape today ( boards start @ $1200 ...glass jobs a grand...rest $200 as it should be )

standard pu build too

his foiling his fins much thicker in the tip....they look trippy

he also had a big bitch about fcs stealing his inside foil design....his been doing for 15 odd years

patents....for a grand a board he could have afford one

but i do like his trippy fat tip fins.....something about em....i'll try post pics later this week

[Cpt.Caveman]

I've read that most of the drag from a fin comes from the tip of the fin creating turbulence. Maybe his design creates less?

[dUg]

Interesting theory, I'd like to see some scientific basis though. Air is essentially a fluid as far as a wing in concerned, and you don't tend to see aircraft with big blobs on the wing tips unless they are full of fuel.

[Quangers]

No, but you do see the 'up-turned' tips on all of the bigger planes which make them more efficient.

[dUg]

No, but you do see the 'up-turned' tips on all of the bigger planes which make them more efficient.

^^ yep... they seem to work in fins too. I have a set of the old Carbon CR-V's in an 8'2" I use when it's tiny at home over summer, and they transformed that board.

Also the little "winglet" things you see on the end of some wings, very similar to a 3D red tip. Oddly enough I have never surfed one of those... been meaning to give it a go.

[Quangers]

I was thinking about it, and it dawned on me that it is the same purpose achieved by the famous 'winged keel' - still doesn't fin drag help to stabilise a board?

[Cpt.Caveman]

Its the fin area redirecting the water that creates the hold, less drag will just make it faster in my books

[Little]

Does anyone here have any idea of how fast a surfboard can actually go? Like what kind of speeds are those guys doing down the giant wave faces, or what kind of speed are you getting at 4 foot fast point break and is there a massive difference between those two or only a few kph? What I'm trying to determine is the terminal or maximum speed of a board in maximum speed inducing conditions as opposed to top speed in average, peaky surf, or say scooting along a quick little shorey where you think you're really flying. Relative to all that, take a 45 kg grommet compared to a 95 kg tub ( me ), both on suitable equipment in same reasonable conditions, what, if any difference in down the line speed. You would expect the grom to be far quicker because of less drag in board planing area and weight being pushed but that doesn't appear to be the case. What if the grom jumped onto the tubs board, with greater planing area hence greater lift, would he be moving faster still or is the increase in lift negated by the inrease in drag, which would also explain why mals are no faster than shorter boards? Or does it? How much effect would any type of fin have on any of these outcomes?

[alakaboo]

Roy?
Paging Roy?

[Nick Carroll]

Little, board speed isn't a zero sum game and is heavily influenced by the skill of the rider.

A good board will go as fast as the wave and rider will permit it. The fastest surfboards in the water are those being ridden by guys in big wave tow situations, which are always very low-planing-area craft designed to minimise unnecessary drag (while making sure every bit of drag counts for something!)

Fins are like any other board design feature, they're a weighing up of drag versus release. A fin always drags more than no fin.

At the Quik Pro at Snapper earlier this year, a GPS based technology firm gave surfers the option of wearing speed tracking devices in their connie singlets. I don't have my notes available from it but from memory, it was rare for any surfer to top 50km/h -- and Fanning got top speed exiting a deep barrel early in the event.

Roy I am sure his boards go at around 300km/h.

[Little]

Thanks Nick, that's interesting. I wonder what everyone would have guessed as a top speed, I'm not sure I would have gone as high as 50 kph. Now that we have some sort of speed benchmark, how much difference do you think fin and foil variations would make? We all understand a flatter rocker, concaves etc make a considerable difference to speed, possibly around 20% (?) but fins? Practically speaking, every board needs at least one fin and it's universally agreed that a couple more make for a better surfboard. Is there enough refining left in modern fin design to make any significant difference in speed. I think Webber is all about exactly what you stated, every bit of drag counting for something, fins being rudders retaining or developing power through turns rather than actual board speed.

[dUg]

I'd like to throw in transient vs. average speed as well. You're going a good deal faster coming down after jamming the tail beneath the lip than you were on the way up, same as exiting a fast barrel compared to the start. I think it's in those situations you get a feel for what regular surfboard ( as opposed to a 15" x 5' wide tow-in sled ) does at speed. I know a few blokes who kite on typical 6' type shortboards, and I'm pretty sure they get up to speeds a lot higher than 50kph. They tell me fins are critical and cavitation is a major issue for them, all preferring more swept back templates and only fibreglass or carbon laminated fins. Of course, drag isn't as big a problem because they have a giant bloody sail to compensate.