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Surfding
Lets add something else to the equation.... surface area.
Aku doesn't do surface area, you have to go to BoardCad.
BoardCad shows you what the surface area is but does not graphically represent it so that you can see small variations,
To get a graph of surface area you have to go all the way back to DAT98.
Surface area is one of the variables of floatation and adds to paddle power because it increases the boards ability to plane early.
Talking about volume is really one dimensional, it is a start but only for the same size and shape of boards.
Boardbumps
Sorry to get all reductionist on your ass, but there were several examples of wooly thinking (occupational hazard for denizens of the valleys?) that I will not let pass…
A bit harsh. The maths is OK as long as you don’t start bunging in unquantifiable variables.
That’s a damn fine example of an unquantifiable variable, so we shouldn’t start throwing numbers at it, I agree.
The only floatation quality I can think of is density… y’know, weight/volume… unless you are using special materials like handwaveium or unobtainium.
Talking about ‘floatation qualities’ is a bit hippy-dippy/feng shui/holistic healing. 
Not sure what you are driving at here, but it sounds a bit arse about face to me. The volume of a board is the volume of a board (as long as you don’t change the shape). Unless of course you are gonna glass it with super thick skins and make the whole board fatter. Lets see, an average glassing schedule on a shortboard would prolly add 1.5mm on all sides to a shaped blank (does that sound reasonable?).
<noises off, rummages with BoardCAD>
So a 6’x19"x2.5" shortboard gives us a figure of 28.811 litres. If you were to increase the skin thickness by 1mm above the standard 1.5mm schedule (a 2.5mm skin would be pretty extreme, but it helps to illustrate the point)…
<more rummaging>
the volume would go up to 29.366 litres, that’s an increase of 0.555 litres of volume. Bear in mind that was by nearly doubling the thickness of the skin.
The change of volume of a board by thick glassing, glossing or excessive sanding (of the laminate) is pretty negligable.
<exits, persued by a bear>
Where you do have a point is the difference in weight that variations in lamination cause, this does not affect the volume unduly (see above), but definitely affects the density of the board, and therefore the bouyancy.
“If it wasn’t for you pesky meddling unquantifiable variables I would have got away with it too” (the ghost of Scooby Doo lives). So, yes, fitness does not earn its place in any algorithm.
(unless of course you wanna get busy with BMI/VO2 max/etc… nop, I thought not)
A little defeatist, but I feel your pain.
Let’s have a look at those variables,
UNQUANTIFIABLE VARIABLES
- rider fitness
- wave type
- rider preference
- board shape (too much interplay between the known variables there)
QUANTIFIABLE VARIABLES
- board volume
- board weight
- rider weight
weird comments, you say i'm arse about face but within your post you do same kinda thing...anyway, all good, we agree there are many variables...if you wanna do your maths, go for ir, I'm sticking with my knowledge and good communication with my customers, has worked so far just fine....
feraldave put it well I think.....
Yes I apologise I did sound arsey and somewhat pedantic there. I went back and re-read
more carefully, and I think now I understand what you were driving at.
Where I got it wrong, was I thought you were saying that different glassing and sanding would affect the volume. So I thought I’d better point out that it really wouldn’t affect volume much at all. Now, I realise you were saying that different glassing and sanding would affect the **weight **and therefore the design volume would be inappropriate for the rider.
My bad, sorry.
Talk of an algorithm is a bit misguided methinks. But before the Luddites throw the baby out with the bathwater, I believe volume is just as important a ‘dimension’ as length/width/thickness. It just seems strange that surfers (and some shapers) just don’t know the volume of their boards. We have the technology, there is no excuse.
[quote="$1"]
Talk of an algorithm is a bit misguided methinks. But before the Luddites throw the baby out with the bathwater, I believe volume is just as important a 'dimension' as length/width/thickness.
[/quote]
Exactly. I wouldn't want to go back to the days when I didn't have the extra tool.
Planing surface/area is the next dim we'll be writing on boards.
good shapers know the volume of foam without a mathematical formula, they know from experience in the water riding alot of different surfboards ( and materials ) and regularly, they know from all the learning they have done over the years, if they know it from a calculator, I wouldnt be getting my booards from there. ( possibly an additional tool for some but not for me.)..just my opinion, I know some value all the tech stuff, but for me it comes from discussing a boards requirements with the customer and then creating a board with the apprpriate volume for him, so many variables and they must all be taken into consideration...I think volume is one ( if not ) of the most critical design elements of any surf craft....
for shortboards volume isn’t very critical for me as long as its not too thin. Recently i’ve been happy on everything from the Byrne “macca pro design” potato chip (still a reasonably thick cut chip at 2 3/8") to the 3" thick McCoy nugget.
Where volume gets critical for me is on step-ups and mini-guns. Being able to duckdive is an extremely helpful quality and keeping the foam where its needed and shaving it away from where it isn’t matters. However don’t ask me what my “marginal duckdiving volume number” is. So far two custom shapers got me duckdiving via their intuition (no vol numbers) on a length I failed to duck with my own self build. I also managed to choose a stock mini-gun wisely which I could duckdive. What happens with me is that up to a certain combination of volume and shape I’m duckdiving effectively and then just a little bit more tips me over the edge and I’m hopeless.
So stoked you feel that way!
I know shapers that are more experienced than you can ever imagine and make boards for some of the worlds finest that use math.
Using science, physics, mathmatics in your craft is not a bad thing. The great artist of the 1500's used all those tools to create the finest work of art in history.
The VA tool gives you the value of the volume you just shaped into the board.
IT'S A REFERENCE POINT!
Exactly, a reference point. Having had two boards from Mike with the volume on them has got me much more in tune with my boards and how much volume I need. It allows for another quantifiable measurement, rather than “boxy”, “knifey”, etc. If the shaper/rider know what the volume they liked before they had a wife, kids and a beer gut, they can do the math and figure out where they should step up their dims to. Life is too short to ride bad boards.
Glad you chimed in, r.o.w. Customer feedback like yours has proven to me the value of quantifying volume.
Solo - just got me a secondhand nugget......thicker than anything i've ridden before with a wider tail too. I noticed today that I float at about the same level (ie just below my sternum) as skinny rippers on their 6' 2" X 18" chips.
Why did I ever try and ride anything with lower volume before? At 225lbs, the nugget's about right volume wise for me....caught loads of waves.....had fun.....wave count up there with the skinnies.....yeeeeeehaaa.
Over the years, I’ve determined what volume and what surface area I need in a board to make it work for me. When those two parameters are met, I can pretty much ride any board and catch waves with it. It works for me.
Just a data point I wanted to share.
Formula:
Thickness . Width . Length
2.0" . 18.0" . 6’0" = 22 Liters
For every 0.1" change in Thickness add/subtract 1.2 liters
For every 0.1" change in Width add/subtract 0.15 liters
For every 1.0" change in Length add/subtract 0.5 liters
Example Board 2.25" x 18.6" x 6’1" = x liters
2.25-2.0 = (0.25/0.1)x1.2 = 3 liters
18.6-18.0=(0.6/0.1)x0.15 = 0.9 liters
6’1"-6’0"=(1/1)*0.5= 0.5 liters
22 L + 3 L +0.9 L + 0.5 L = 26.4 Liters; BoardCad gives 26.6
It’s not perfect but works pretty well for boards 5’ to 7’ after 7 feet it can underestimate by 10% or so…
looking forward to it 
interested on how much the experienced guys are increasing the .35 formula for their team for step ups, and grovellers?
personally my good wave number is 30-31L litres, my not so great wave board is 33-34L, and my short super fat groveller is around 38L from memory.
26 TO 27 LITERS IS AVERAGE FOR A FIT EXPERIENCED SURFER = Groveler (MID TWENTIES TO MID THIRTIES)
28 to 30 LITERS FOR STEP UPS (LARGER SURF)