18 Holes with a Mako

[surfhorn]

Mako Shark may be the key to design of faster Surfboards

Shark Industry News

Why a Speeding Shark is Like a Golf Ball
Sharks Raise Their Scales to Dimple Their Skin Like the Surface of a Golf Ball

Is this be the future technology for Surfboards ?

Surfersvillage Global Surf News, 10 November, 2008 : - - Shortfin mako sharks can shoot through the ocean at up to 50 miles per hour (80 kilometres an hour). Now a trick that helps them to reach such speeds has been discovered – the sharks can raise their scales to create tiny wells across the surface of their skin, reducing drag like the dimples on a golf ball.

The minute scales – just 200 micrometers long – are made from tough enamel, such as that found on teeth, giving the skin a rough texture like sandpaper. Lying flat, they had previously been found to reduce drag as the shark swims.

Some reports had also suggested that sharks can bristle their scales, causing them to stand up on end, so Amy Lang from the University of Alabama in Tuscaloosa and colleagues decided to investigate whether this too could help sharks travel at high speeds. The team created artificial shark skin with a 16 x 24 array of synthetic scales, each 2 centimetres in length and angled at 90° to the surface of the "skin".

They then placed the arrangement in a stream of water travelling at a steady 20 centimetres per second. The water contained silver-coated nanospheres, which a laser illuminated to reveal the nature of the flow around the scales.

Golf-ball effect

The experiments revealed that tiny vortices or whirlpools formed within the cavities between the scales. These vortices form a kind of "buffer layer" between the skin's surface and the fast moving fluid, preventing a turbulent wake from forming behind the shark. Since a wake has a lower pressure than the rest of the fluid, it exerts a backwards pull on an object, decreasing its speed and making it harder to change direction.

Eliminating this wake decreases the overall drag on the shark, allowing it to travel faster and move more easily without the thick, syrupy feeling humans get as they try to move through water. "It's like the difference between pushing a box over ball bearings instead of dragging it along the floor," says Lang. The same principle explains the dimples on golf balls, which also create mini vortices to reduce drag in this way, she says.

Ultimately, the team hope further investigations could be used to design torpedoes, underwater vehicles, and even aircraft inspired by shark skin that can move more quickly through water and change direction more easily.

Sergei Chernyshenko, an aeronautical engineer from Imperial College London, UK, describes the research as fascinating. However, he points out that while the team have shown the existence of vortices, they haven't yet quantified the extent of the effect on the shark's drag, which he thinks could be minimal.

[skansand]

this has been mentioned on the flexspoon site....

some well known shapers include course sandpaper with a new board so you can rough it up if you want....

i think someone will make a shark skin fabric thats laminated to the board....

spray traction has potential but wont be as uniform..

[mFox]

Why stop at the skin!!!! throw in the teeth (on the nose and rails) for those crowded days for some real fun

[knee_boarder]

didn't some one try the golf ball idea back in the late 80's, early 90's?

[Doc Turbo]

at one time 3M was experimenting with in field tests with a textured film PSA (pressure sensitive adhesive) for aircraft and boats.

I expect some have also experimented with this on boards.

[RMcKnee]

some well known shapers include course sandpaper with a new board so you can rough it up if you want....

In the boat business years ago, (and I mean many!), some people thought they'd get an extra knot or two out of their racing yachts by putting a high gloss sprayed finish down below. Research eventually showed that the spray pattern profile, (which could be measured in microns), actually created more drag than the same surface wet rubbed with a medium grade paper, say 240 grit or finer, and in a random pattern.

This led to the America's cup boats going for fully faired hulls sprayed in polyurethane and then wet rubbed to 1200 grit. I believe this is still the racing standard these days.

An innaresting example of how far this sort of stuff can go and the potential for unexpected outcomes is the fate of the Aussie challenger in San Diego in ... I dont remember when it was. Trying to get an extra eighth of a knot, the skipper had the boat so highly tuned, (which in part means the mast was under a lot of compression force generated by tension in the forestay and the backstays,) that the bow and stern ended up getting pulled up toward the top of the mast.
This broke the boat in two and she then went really fast; straight to the bottom of the sea.

There's a lesson in there somewhere.

[KenM]

didn't some one try the golf ball idea back in the late 80's, early 90's?

I think the Willis brothers were making something like this with big dimples, about 3" diameter.

[ted torrey]

Please correct me if I am wrong, but I think the top speed of a surfboard (not towed in) isn't fast enough for dimples of any sort to work. I think there has to be enough speed to decrease friction with water on water adhesion vs. a wake. Anyone know how fast a surfboard actually goes

[Steeno]

I'd agree with Ted, in the 80's here....dimple boards where everywhere, at least 4 manufacturers in my local area. they where not a great a success...nor any noticeable speed difference. and a s*&^ to glass and sand

but what about on heavy weight Tow boards?

[ted torrey]

I used to work for G&S a while back and built many textured bottom boards. The way we mostly made them was to take a laminated board then squeege the hot coat resin on leaving a glass weave texture. The boards were very light but not very strong, but strength was not really the objective. This was supposed to allow either one of two things to occur: first - create a small bead of air to create less friction, this was introduced by Tom Morey if I remember right.
second - create water to water contact to offer less friction a la the golf ball concept.

However neither thing really worked like it was supposed to and we used the same technique to acheive opposed concepts.... go figure

[womble]

All the boards I have owned have had dimples.
I’m not sure if it enhances the performance in anyway.

I put them all over the deck.

Must be my big bony knees.

Another random analogy and no help what so ever.

I am trying.........................................................

And the reply is....... We know you are.........very trying.

[ted torrey]

btw Steeno, I do think the tow boards could have an advantage at the speed they travel.... perhaps a full dimpled bottom...but maybe too loosie goosie

[Steeno]

its an interesting concept and the wording above about the sharks raising their scales when they get to high speeds, and the whirlpools creating a buffer zone...kinda makes sense...but does it have a max speed before it does the opposite

[ted torrey]

My guess it's more of a minimum speed issue. Low speed, no need.I have a ding about the size of a walnut on the bottom of my 5'10" fish. I think I got it paddling out the other day, I didn't notice it 'till I got home. It didn't seem to affect my session at all. But I suck anyway so how would I know

[Mike Fernandez]

Perhaps the world of nano technolgy will come out with something. I can see a paint being invented that has the molecules line up a certain way before it dries.
Maybe a resin could do the same thing.
I doubt if dimples work in the water, or else the powerboat racing/America's Cup/US Navy submarine folks would have figured it out. It wouldn't be hard to apply dimples to a soft surface with a custom roller.
I'm too young to golf, but anyone ever heard of the "happy nonhooker" golf ball? It's illegal in the golfing world of which I am too young to participate in.