Remarkable board

General Discussion
21

I’m confused…

you were there yesterday, Balsa said we shoulda been there yesterday, you say concaves are “out”, so concaves were yesterday… man my head hurts… WHATS TOMORROW!!

LOL!!

Seriously though, Bill, many of us here must be gloriously mistaken then when we ride our concave adorned sticks and think ooohhh. speeeeed… well actually… I think, imho, that concaves give me acceleration, when given a proper rocker and fin etc, but of course I wasn’t there yesterday, I must have been sailing by on flat to V bottomed windsurfer…

22
Quote:

the more contact points with the water, the more friction there is and the more friction

Please excuse me if remark a caveat to this bit… larger surface area may benefit you in terms of favouring laminary flow and associated dynamics… it’s not as simple as surface = friction. Otherwise 747’s wouldn’t fly and post-panamax tankers would be immobile…

23

just passing through , will be out in a second …

im with bill …

despite the lack of technical detail in bills response , his short comment was packed with understanding …

bill you got guru status in my books , not just from this thread but many others ive had the opportunity to swap comments with you …

a drag feature = control feature …

where and how you want the control will determine whats the best curve or package to use …

regards

BERT

24

Bammbamm 808, not only did you start a shit-fight thread but THE one thread that made Bert BURGER drop in since ages…

Hey Bert, I’m with you with drag = control, who wouldn’t? That is precisely what I was saying above. But I will stand by my position: convex shapes mean drag (and control), flat shapes mean neutral, concaves shapes mean less drag (and less control). And, of course, it all depends upon how it’s done.

25

The only thing I can add to this conversation… and I’ve said it before… is that concaves create speed when pumped, providing bursts of speed when you need them. Concaves are all about flattening the stringer rocker, maintaining rail rocker, and directing water flow. Concaves don’t make a board trim down the line faster. They are notorious drag elements. But when weighted for turning they, to a degree, force water to flow (if shaped and placed correctly) in such a way as to cause it to accelerate through the concave features, providing speed.

26

Here’s another log for the shitfire. Maybe it’s the material used for the board. If you have been surfing poly boards, and now you have a light EPS Rawson with more flex & snap, yes it might be the bottom, but i’m thinking material might be the culprit. At least that’s what I’ve found out in my limited time working with the stuff.

27

Concaves are for control, not speed.

28

how so?

29

Concaves can be used to alleviate some of the water resistance of todays constant rocker short boards, they are like a cheater flat spot in a constant curve, but…they have to be done right, start too far forward and they push more water, stop too soon and they create cavitation and lift in the tail which causes the board to bog. I’ve ridden flat bottom shorties in the same dimensions as my everyday board and they were not as quick off the line (first pump, bottom turns, round house recovery) as those with concave, although the down the line speed felt the same.

Flat fish are fine, flat mini guns are fine, but give me concave in the short board.

30

A flat surface will plane over the water with less resistance - because everything is in alignment. Any differences in bottom shape will redirect the water’s path, causing drag. Concaves cause the water to travel farther over the board’s bottom, creating sort of a reverse lift, or suction to the wave face.

Bottom contours are always about control, not speed - an exception is the Bonzer, which uses a venturi to speed up the velocoty of the water at the fins.

A lot of towboards have a full single concave. They don’t need a flat bottom to go fast, because they have the energy of giant waves to make them do that. What they need is control. Concaves give them that. Noseriders sometimes use concaves in the nose to help suck them down up front.

Belly causes the water to follow the boards bottom to and around the rails, and helps keep the water attached to the board - at the rails.

V’s are about getting the board from edge to edge easier. A double-barrel V combines V with concave to give you the best of both - holding power, and the ability to transition into and out of turns.

Nose rocker is there to keep you from plowing your nose during paddling and takeoffs (mostly). It also presents more surface area to fight the water and creates drag. That’s one of the reasons why the noses on guns and thrusters are so pointy - less surface to push through the water. The template/rocker combo also helps turn the board out of critical spots like the pit of a steep face, and get you into a place where you can control the board more from its center or tail.

Tail rocker gives you a tighter turning radius off the back of the board, and will make it looser. Water deflection will also cause some drag, but it won’t be as noticable as nose rocker.

Every surfer has different needs and sensibilities. That’s part of what makes surfing so beautiful - there is no single right or wrong, or magic board. That’s also what makes it more art than science. If you’re always on edge, you’ll be faster on a board with more rocker and some V. If you like speeding down the line, you’ll be faster on a board with less rocker. Some surfers like to overpower their boards. Others like the board to do most of the work. Wave shape and size, along with surfer weight, size, ability, and sensibilities determine what’s right for each person.

31
Quote:

Bottom contours are always about control, not speed

I shouldn’t have said “always”. As I pointed out the Bonzer is an exception. There are others too. It’s a combination of all the elements working together. Also… a lot of shapers don’t really understand what bottom contours do, and just follow their gut, or what they’ve seen on other boards.

32

I could be off my “rocker” here, but single concave on a continuous rockered board slightly flattens the nose-to-tail curve along the stringer, making the water travel a shorter distance, not a longer distance. Right?

33

Speed depends on the rider’s skill more than any other factor.

Generally speaking, assuming average conditions and same length of ride, the surfer who can do the most top to bottom re-entrys is likely going the fastest.

Ive been wanting to mention this too…

if it were all about speed, everyone would be riding stiff, flat rockered, flat bottom single fins (no one would be riding three fins!)

But most of us dont ride boards like that cuz its gotta handle good (personally handling is more important but thats just me - I prefer Corvettes).

This “analyze speed in a vacuum” discussion seems out of pop surfing’s relevant context.

my $0.02

34

Try the old Tom Morey “spoon in the faucet” trick. Dangle a spoon by the handle in the stream of running water… first the concave side, then the convex side. See for yourself why Skip Frye has been quoted as saying, “Round bottoms suck - literally.”

35
Quote:
I could be off my "rocker" here, but single concave on a continuous rockered board slightly flattens the nose-to-tail curve along the stringer, making the water travel a shorter distance, not a longer distance. Right?

Yes… and no. If you were going in a totally straight line maybe. The thing is, surfers rarely go in a totally straight line. There’s almost always some diagonal flow across the board.

By the way… here’s one of Renos guns again. He put a channel down the middle for exactly that reason - flatten out the rocker through the center. He also put concave in it to help hold it to the wave’s face. I haven’t tried it yet, but I’m itching to.

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36

I must admit I hold my own views on concave. They can be used for control in many ways, in the nose or center of a board. However the double concave in the tail is about releasing the build up of water caused by the fins when you turn hard, which otherwise would cause more drag. To see this effect get a swim float in the swimming pool, immerse it in the water half way. Now push it across the surface, you will see water build up on the side that you are pushing against. I think concaves relieve this pressure and allow the water to exit the tail quicker.

I don’t believe that bonzers work on the venturi principle (& I’m a bonzer disciple) Duncan has way too much success converting pro’s standard shortboards to bonzers for that to be logical. In a bonzer you will notice that the concave is deepest at the fins, which imho links in with my thoughts on the issue. I also believe Berts observations are valid on thin tailed double concave potato chips.

37
Quote:
I don't believe that bonzers work on the venturi principle (& I'm a bonzer disciple) Duncan has way too much success converting pro's standard shortboards to bonzers for that to be logical.

I was a Bing team rider in the early 70’s. That was their claim at the time. My time on Bonzers is mostly limited to the dozen or so boards I had in the 70’s. They’ve had 30+ years to refine the design… and their thoughts about the theory behind it.

38

i find it funny that here you are riding some of the best waves on the planet with access to some of the best shapers on the planet and have a board from a shaper who makes some of the best proven high performance boards in the world.

You provide some actually feedback based on the fact that you’ve probably ridden just about about every other “state of the art” design people can’t even get their hands outside of Hawaii, and you get all this feedback about this or that from folks who have no clue of what you’re trying to communicate to them or maybe who Pat Rawson is…

blows my mind…

I bet sir wanky is shaking his head about this all too…

The fact that this is a Rawson (which no one seems to understand what that means) and that this is EPS and that the board rocks without a trendy concave or fancy bottom seems to blow by everyone.

Folks don’t seem to remember that that Pat was one of the first guys to commit to Duncan’s 5 fin bonzer concept with Davey Miller in the early 90’s. And now he’s back with rolled bottoms…

Hmmm wonder what he discovered after all those years and all those thousands of boards?

Probably what Bill and a bunch of folks here already know too…

The intenet is an amazing place…

39

I agree, concaves decrease the distance the water travels and correctly placed concaves actually cause the board to lift or plane higher which makes them easier to turn.

And when I’m talking about speed it’s not how fast the board goes in a strait line, it’s the quickness of the bottom turn, release from floaters, recovery from off the top and maintaining speed through cutbacks.

40
Quote:
Speed depends on the rider's skill more than any other factor.

Generally speaking, assuming average conditions and same length of ride, the surfer who can do the most top to bottom re-entrys is likely going the fastest.

… and the guy who’s going fastest can do the most top to bottom re-entries.

Sorry I’ve drifted off the original topic about how cool the Rawson is… Did you ever see BK surf Sunset? Holly crap that dude surfed fast. Surfer ran a photo sequence of him dropping into a double overhead wave with another guy. He went top to bottom four times before the other guy got through his bottom turn. BK rode 17" wide Brewers.

Quote:
if it were all about speed, everyone would be riding stiff, flat rockered, flat bottom single fins (no one would be riding three fins!)

But most of us dont ride boards like that cuz its gotta handle good (personally handling is more important but thats just me - I prefer Corvettes).

It’s all about balance… and everyone gets something different out of surfing. Some guys just want to go fast. I prefer to make love to the wave, and not leave it too far behind me. It’s a dance… not a race… except at Maalaea… there fast is a good thing.

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