volume algorithm - avoiding the slater copycat phenomena

General Discussion
1

Ok I’m no mathematician or physicist so I pose the question to those who are.

Assuming that it is generally agreed that:

a) different design types will perform differently depending on conditions and rider experience

b) changing one variable in a boards design changes all other variables

c) a board which does not float the rider well will not work as well as a board with adequate float

The question I have is regarding float. Is there way to create some sort of algorithm that could be used to determine the volume needed for a board, regardless of design (retro, performance, etc) for a particular rider?

Example: say I am 5’7” and weight 170 lbs. I want a modern quad fish made from a poly blank, heavy glass and resin tint and gloss. I am an average surfer. Could not then, there be some formula by which you could determine the minimum overall volume of a board of this design for my weight and ability? That same formula could be used for any other person and board types.

The person would get the design characteristics that they requested (if a performance board then performance or if a retro single-fin then the same) and yet be able to also get the most ideal amount of float.

I see a lot of guys on hi-performance boards that are too small for their weight and ability. The formula could help them in getting the same design concepts but suited their specific needs.

I imagine it would something like:

Rider weight (displacement) x desired float for board design (lower volume for high performance and more volume for fish etc.) – weight of finished board (gloss and polish will weigh more than the same exact shape in EPS) = total ideal volume for that design.

Any thoughts? Am I missing some really important variables? I know that it’s practically impossible to calculate volume of a compound curve object like a surfboard by hand but it can be done buy computer no?

This formula would also help all those poor souls lining up to get Slater’s latest BMI challenedge board.

2

If you want to shape boards your on the right track

you could grab a freeware board design program

that will calculate your current board volumes.

It all relates to experience. There is no explicit formula

or chart, although there may be at RonJons.

Or you might try what archimedes did, but I think

the cad programs are easier for this time.

If your not learning to shape, then this endeavor

might be a fluffball of wasted time as your current guesstimations

of width and length,thickness will carry you further that you confide to

your shaper.

3

To create an algorithm wouldn’t you need to know the optimum performance level. That optimum is unknowable right? I know this gets to that nexus between art and science but it seems to me that the optimum level of performance would constantly change with all the variables that effect an object moving on a wave… not to mention the qualitative stuff like style and ability. I have to laugh when I parse dims and contours and weights, rails … sanded finish vs. g and p - that’s my favorite. Anyway, I’ve always wondered which design would be say the fastest a to b. Drag racing surfboards, put them on a dyno first then race em. Cool thread, I hope the gurus jump in.

4

I use a really simple metric - litres volume per kg of weight…

Put my board dimensions into AKU shaper software to calculate volume e.g. my 6’ comes out at 27 litres.

Weigh the board e.g. the 6’ compsand is a light weight 2.2kg.

That gives me about 12.3 litres per kg, I’m 5’9" and 70kg.

That compares with 7.8 litres per kg for a 6’6" polyester step up board. The 6’ floats me and catches average waves much better.

But once the waves get well overhead and start jacking, the narrower tail on the later board comes into play on takeoff ie better release to get going.

My 5’8" compsand fish is 13.2 litres per kg and catches wave even better, but that’s also the wide fish tail getting on the place earlier.

Hope that helps

Karl

5

I believe that Prof. Loehr at one time mentioned a way to figure out a boards “volume” that had to do with multiplies of the length, the widths at nose, tail and center and thickness. hopfully he will have the time to explain it to us again.

In the meantime, I love having the crowd full of guys on the wrong boards. Just think how nuts it would be if waves were never missed by all the chip riders.

Aloha, Tripper

Search the forum for “volume” and you will find a couple of discussions from 2007 about your very topic.

6

“Foam is your friend.” -Rob Machado.

In my very limited shaping experience volume has been a stumbling block. First, I hate…no I HATE board with not enough volume. Nothing worse than missing the wave of the day, knowing that with a little more float you would have been on it. Lately I have been playing with AKU shaper and it’s a big help. At least I can compare volumes of different boards. That said, knowing the volume is not enough. It’s all about VOLUME DISTRIBUTION. And unfortunately I think the only algorithm for that is… EXPERIENCE. I say unfortunately because it’s trial and error and I’m afraid when I finally figure it out…I’ll be dead.

7

“Foam is your friend.” -Rob Machado.

In my very limited shaping experience volume has been a stumbling block. First, I hate…no, I HATE boards with not enough volume. Nothing worse than missing the wave of the day, knowing that with a little more float you would have been on it. WCT guys can air drop late into waves on super low volumeboards because they surf in two man heats. If those WCT guys had to surf in a typical crowded line up, I wonder if they still be on chips? If they were still on chips my guess is they’d be burning a lot of longboards and funboards in order to get waves.

Lately I have been playing with AKU shaper and it’s a big help. At least I can compare volumes of different boards. That said, knowing the volume is not enough. It’s all about VOLUME DISTRIBUTION. And unfortunately I think the only algorithm for that is… EXPERIENCE. I say unfortunately because it’s trial and error and I’m afraid when I finally figure it all out…I’ll be dead.

8

That is most definitely NOT generally agreed.

That is a function of skill level, fitness, experience etc etc.

A surfboard is a planing surface. At higher speeds , there is a greater upwards/lifting force on the planing area.

Therefore highly skilled surfers who can get their boards going fast quickly (or tow surfers) can ride, and choose to ride, lower volume boards for the control and sensitivity.

There’s probably a correct volume for you in your home waves, but you might want to lower it for, say , perfect surf in Indo.

Also depends which craft your riding , and what feeling you want.

eg a log for gliding knee high babyfood will be obviously different to a foiled semigun for perfect surf.

But I think your right, modern hi performance potato chips are suitable for only a few.

9

Volume (in cubic feet) has been written on the bottom of every Coil for about the past three years. It’s a great tool to have when working with customers to fine-tune things. You also find out that there’s a great deal of personal preference in bouyancy needs, i.e., some guys like to float, some like to swim…

On one of those 2007 threads I laid out my general guidelines for different types of boards. For shortboards, it’s about .50 cubic feet per 100 lbs of rider weight, fishes and hybrids about .75 cubic feet/100 lbs, eggs and mid-lengths 1.00/100 lbs, hp long 1.25/100 lbs, and classic long 1.5+/100 lbs.

edit to add that 1 cubic foot = 28.32 liters, I like using cubic feet more because it’s easier to see percentage changes. (most shortboard #s run between .70 and .90)

10

I avoid like the plague generalized formulas for board specs, although like Mike Daniel says there is definitely a place for an individual rider to use volume as a guideline for his personal boards.

A little pinch here or there can skew things all over the place as well as is the bulk of the volume centered?, fore?, aft?, etc.

There are displacement tanks that allow sinking an object like a surfboard and measuring the exact displacement of the water in the tank. All you need to know are the dimensions of the tank and how much water is displaced when the board goes under.

It might also help to keep the weight of the board constant as a heavier board with equal volume won’t float as good as a lighter board… that’s what buoyancy is all about - not EPS/epoxy vs pu/pe.

Mike - how do you calculate your volume?

11

Many of the guys that ride boards that do not float them, do not care. It’ about keeping up with with what is considered cutting edge or current. With older guys that surf good…it’s often to prove they can still cut it.

Boards with more volume work better…period for 95% of the surfing population.

I don’t think any board should be under 19.5 wide nor have a tail narrower than 14’’ unless it’s a gun or really hollow waves ( even then if shaped right the wider tails can work ) or your dealing with a really light little kid. Under 200 pounds anything between 2.5 and 2 7/8 thickness works. Anything over 200 pounds for shorter boards is 3’’ to 3 1/4’'. On average.

A shaper worth his salt will want to know the type of surfing you want, where you will be surfing, your experience and to see you in person or a picture. The best of them…just know. No math needed. I have rarely been let down by a quality experienced shaper when I told them what I wanted. Except when they went thinner. I can’t think of a time when thinner is better.

You have heard it said that " Nothing is almost always the correct thing to say "

Well…going thicker and wider is almost always the right thing to do.

12

I can see why you would want to avoid that one. It’ll be kind of like using an alogorithm to determine what someones favourite colour is.

13

if you are making stringerless eps boards - you can weigh and measure your square block of foam before you cut it to get an accurate average density for the foam (or get the info from your foam supplier - but i think the density for a given foam can vary a bit from block to block)

then weigh your blank when you are done shaping - do some cross multiplying and you’ve got a fairly accurate volume measurement!

14

maprofessor,

In MHO the question of board volume has to be considered in two different contexts: whether you are planing (up and riding) or not-planing (paddling, catching a wave).

When you are up and riding, I think its the rocker, plan shape and rails that are more important than volume in how determing how the board rides. When you are paddling its the volume that is more important than the other factors. Which is not to say the other factors do not matter, they do.

IIt seems to me that if a shaper can put more volume into a board, while keeping the same rocker, plan shape and rails then that board will paddle better and perform just as well on the wave face as a lower volume board. There will be some impact from the volume when riding a thicker board as the thicker board will have less flex, and the deck will put you higher off the wave surface. So you will lose a bit of sensitivity, but not much.

As to what volume you need, I think thats a preference based on the rider, and is related to weight, ability and fitness. Basically to determine how a board will float you take the volume of the board in litres and subtract your weight plus the board’s weight in kilos.

So I’m 85kg, and I’ve found the smallest boards I like to paddle are around 50 litres. That is, a board that gives me negative float equivalent to 40 litres (50 - 86 - 4).

I would guess that the boards most commonly ridden would be around 27 litres, weigh 2kg and the rider about 65kg, also giving, interestingly, a negative float of 40 litres.

Notice for my preferred board I said for paddling (including catching waves). These boards are around 7’ x 22" x 3’'. Once I’m up and riding I would much rather be on a smaller dimensioned board (in good surf that is). I’m now 58 years old and 85kg. When I was 25 and 70kg (and a lot fitter) I went to Gragagan with a 6’2" and a 6’4" and had a blast.

I’d be interested to find out the negative volume that other surfers are happy with, unfortunately though, this is pretty difficult to do as most manufactures do not supply the volume of their boards.

Dave

15

Hi Dean -

I made a board for a friend… 11’ X 27" X 5". I don’t know of ANY length or volume program that would accomodate those kinds of dimensions but that’s what he wanted. He got what he asked for and seems happy with it. Oh yeah, it’s his shortboard.

16

Shortboard…Really?:?

Interesting thread for me and i often wonder about this sort of thing and whether its really worth going low in bouyancy.

Sometimes im on a good wave fish, some shortboarder will call me off or ill let him go out of good will but he loses the wave and i could have gone the wave of the day. Its frustrating sometimes.

Im 65kg, 5’ 10 paddle fit and above average in skill.

I like short shortboard around 27cc volumne of EPS equal bouyancy in PU/PE

I like my step up and guns getting slowly more bouyant and my hollow wave twin keel about equally bouyant as my step up 6’6 (x 19 x 2 3/8) Fat/smaller wave twin keel a bit shorter but thicker flatter and more traditional.

Im guessing around 33-34cc (?)

My bigger gun is really thin but i dont like it so thin and often wonder why people go so thin.

My good wave fish gets slotted so do my longer shortboards that are about even in bouyancy…Although i found my more bouyant fish better in semi fat waves and my hollow wave fish is the least bouyant.

You can even get slotted on a mini mal if you practice, you just have to push harder in turns and lift legs/compress high and low to get a bit of speed…

For learners and intermediates its definately better to have some paddle power and learn how to ride a wave than to be

struggling to get any waves at all…While your getting more waves you are improving quicker, getting better at paddling

as you’re paddling back out more often…

I would like to see how what real benefet there is to super thin boards…

17

Dave Veral of Diverse has a handy little volume guide on his website check:

http://www.diversesurf.com.au/difference/difference/volume.php

18

I made a board for a friend… 11’ X 27" X 5". I don’t know of ANY length or volume program that would accomodate those kinds of dimensions but that’s what he wanted. He got what he asked for and seems happy with it. Oh yeah, it’s his shortboard.

170 liters

6.01 ft

Lots of volume

19

Shortboard…Really?:?

Yes, the link below is to a resource post of his 12’6" “longboard.”

http://www.swaylocks.com/resources/detail_page.cgi?ID=1829

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20

Just a little query from myself…These two shapes are very similar but i have noticed the TL2 is narrower a little thinner and has a voumne of 27. Im guessing they mean litres. However If you look at the TL1 version it has a volume of 24cc(mistake i guess they mean litres) but my question is would the TL2 be 24?? I just ordered one of these and

i would like to know the correct volume…I cant see how the TL2 can have 27 litres when the tl1 is wider and thicker but has 24 litres…

TL2

http://www.surftech.com/boardDetails.php?bid=SURFBDS+%3A+A0023-0511-STR&type=SURFBDS&shaper=Strech

TL1

http://www.surftech.com/boardDetails.php?bid=SURFBDS+%3A+L1336-0511-STR&type=SURFBDS&shaper=Strech&skill=&weight=&rshape=&cond=&qual=

And before you ask why im getting a TL2, its because i like tufflites for travel…TL2s aswell and to get a stretch imported it would cost me twice as much…Hopefully i could travel to indo with one of these and nothing else.