I agree... and even if the volume doesn't tell you sh1t according to any gain in knowledge of the board... it can help us rank the boards by size, since dimetions like length and width can be similar among 90L and 110L boards so they are not relevant...
so the actual volume gives us some sort of ranking and it is easy to talk in matter of volume instead anything else... some people don't know what N or buoyacy means...either too young or not educated enough (even if Newton is elementary school matter...)
sideskirt - if you honestly believe that then build 2 boards of the same volume but with very different dimensions and weights and see what you think.
cjw - as i have said several times. i have no argument that the terminology has been used incorrectly.
how many times have you heard this at the beach when people are talking about what volume to purchase.
"work out your weight plus the weight of your rig and that's the volume you need to float you"
what's missing from that statement??? yep the boards weight. ever wonder why that concept exists in the sport?
anyways, happy days 
This is interesting and i'm bored. So here's my 2 cents.
I don't agree with using terms inappropriately, which is where barn seems to be coming from, regardless of what you are implying volume is and always has been measured by the amount of water it displaces, you cannot change its meaning to suit a market, that is just dumb.
In more lay terms bouyancy, could be considered as the difference in the density of the material when compared to water. That is assuming that the density of water is 1. (Lets ignore, temperature and pressure, as these both play a role in water's density) Ie a less dense material is more bouyant than water - it floats, a more dense material is less bouyant than water - it sinks
So if most styrofoams/polystyrene foams are ~30 kg/m3, and water is ~1000 kg/m3. Then 1 m3 of styrofoam will float 970 kg. So i would think that to determine the true bouyancy of your board, you will need to know the density of the material, the total volume of the material and so on......
I dare say that due to such complexities and time in determining bouyancy of manufactured products, volume is a simple and cost effective guide as to the supportive bouyancy of the board.
isn't this fun
Gestalt I agree with you on the side of buoyancy brings you real value of the board size and I also agree with Barn cause the one who understands the basics of physics can calculate the buoyacy him/her self and people who don't know anything about these values they don't have to have any data except, to know below 7kg is a pretty light board for use, and a 100L board will be good for me in certain conditions with certain wind strength... so imo actual volume of the board would be better for me in this case cause it is more universal... if you can calculate the buoyancy it is a good value when purchasing a board, but many people don't look at it this way.
Anyway in my opinion since board weight's are pretty much the same (0.5kg doesn't make this much difference in this case) so actual volume can be pretty solid value when looking at what to buy.
i hear what your saying stegs, and that's the way traditionally volume was thought of with windsurfing. because in windsurfing terms it was always referring to bouyancy even though that is technically incorrect.
it's not now, volume now refers to volume.....
what that means is the volume is the same regardless of whether the board is in fresh water or salt water.
well... how come then if I go to a place like Lake Garda an 80 lt board is pretty damn small while the same board is okay on the ocean?
I guess at the end of the day the point is if I you have 5 boards in a given range from a given board maker you know that a 100 lt board will float you more then say a 90 lt board. At the same time if you take a 90 lt freewave board from board maker A and compare it to a 90 lt freewave board from board maker B it will pretty much be the same as far as floating is concerned. Yes, the width of the board comes into play as well but in essence a 90 lt board is a 90 lt board.
It seems in this case people have different opinions on how they interpret the volume marking on boards. So for what it's worth a 100 liter for me means I'll have heaps of fun... an 80 liter board... not so much.
My point is, we all know boards are measured in volume, and were all perfectly capable of doin a little maths in our head to get the buoyancy, we don't even need a computer.. But why bother.. They are fundamentally related so you can't argue against volume in favor of 'old school volume' (pseudobuoyancy)..
It's very easy to use your "old school" method of dunking a board with weights to get the buoyancy, brilliant.. BUT.. then you take the board out, weigh it, And then calculate the volume.. It takes an extra 5 seconds.. And whichever Shaper missed the last step and still called it volume is, as cjw so eloquently put it, an idiot.. fundamental terminology cannot be messed with..
Now is Buoyancy important?? This is actually sorta interesting (relative to the rest of this thread)... I can uphaul a 72 litre board, I weigh 78kg and my wetty weighs 3kg, harness probably 2kg and my rig probably weighs 10kg... and my waveboard weighs about 7kg.... So that's about 100kg on about 70 litres... So my buoyancy is..
70-100=-30
-30*9.8= -294 Newtons of buoyancy
Is that right? Its 2am and I've been playing halo reach for 4the last 5 hours waiting for resin to cure, So someone please correct me..
But 90% of the time a windsurfer not in water displacement mode anyway.. So its not important..
*edit, my buoyancy changes the instant I get my ankles wet, And this is for fresh water, I sail in salt... And there is also downwards force on the sail, mast base pressure so the "virtual weight" of the rig is probably way over 10kg so looks like well need more data to get the buoyancy..
i'm pretty sure barn that they weren't idiots and were aware that technically it wasn't the volume that they were measuring. same as when they measured volume of the resins and foam during shaping. but if you guys must call people idiots then so be it.
what you're not getting is that generally, whether right or wrong, people think volume instead of bouyancy and early shapers understood people were actually insterested in bouyancy. so there become a grey line with the terminology which is still in play today.
exactly why i said publishing volumes of boards is taking hte piss. people want to know bouyancy and dimensions.
for your equation to figure out bouyancy i believe it won't work , there are to many other factors in play, surface area being a big one as you are trying to displace more water.
anyways, now i can say my big wave board is 117lt awesome, at 65x238x11.5 that's fantastic. most otherboards don't get anywhere near that "volume" for the same size. i wonder why that is????
Who exactly are these shapers your talking about? If they can manage get the buoyancy from a tank, and call it volume, then yes they are flippin idiots to the 33rd degree.. It takes 5 seconds of mental arithmetic to get the volume if you have the buoyancy and weight... Can you name these shapers??
What im guessing, is the shapers have always measures in volume, and have never got the terminology wrong.. and somehow you have just misunderstood, or have talked to a solo shaper who never went to high school..
Um surface area has nothing to do with buoyancy, or volume.. Archimedes sorted this out with the king's crown.. A very long time ago!.
B=V*D-M
Where B is buoyancy in kg, V is Volume of board in Litres, D is the density of the fluid in kg per litre and M is the mass of the board in Kilos.. There are only 4 factors at play..
So my buoyancy equation is correct, ignoring the fact that my legs have their own buoyancy, and I'm in salt water..( I didn't use density in my original equation, I knew I missed something)
Volume can be measured in solidworks... there you can make a 3d model and select it, press evaluate and you get surface, volume, you can get weight of the foam when you choose density... so... to get approximate volume (excluding all the lairs of glass, PVC foam) you just need to weight the EPS core... there is not much work there... so to approximately say the sandwich around the EPS gives extra 2-3L in volume... for a 100L board you need a 98L core...
Nevertheless, I finished my hotwire cutters yesterday, today I'll make final finesses to the templates, tomorrow I start shaping.
With volume numbers I see it only as a guide as outline shape plays a part in how floaty/stable a board feels, heres my say about 120L step tail unit, though it does weigh 11kg its fun for me to wave ride and thats what matters.
Here's what I got from todays hardcore grinding.... 228x65cm 87L (actual volume)... I expected more volume, but I am satisfied, since a 105 and 95 would be to close together imo...
It's not finished yet, needs some corrections, but let it rest a bit :)
here's a snap...
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Sounds about right, similar dimensions to my old joker90.. It looks like your pulling foam beads out of your blank... You should be using fresh aluminum oxide gauze.. Its will sand the Eps better and not rip the EPS apart..
I heard that's how the old school shapers did it..
Yeah it is ripping out a bit, but the board still needs the final touch, I haven't shaped the rails yet as well, cause I gotta make the bottom sandwich first... but it won't happen untill february...
Regarding the board's thickness, the max is between 9 and 10cm...
Can you add a photo or a link to see what this aluminum oxide thingie looks like? I can't find anything on the web... is it the spongie thing?
barn, even after your condescending posts i was more than willing to walk away from this thread. there's no point repeating ones self over and over and i had said my piece.
for you to continue on with sarcastic and snide comments like the last line in your previous post is pointless really other than to force my hand to continue.
so....
as far as naming names, i don't really have to. yes i have spoken to more than one shaper and no i didn't missunderstand what i was told and neither did they. at some point you need to realise, as i have, that there are people whom have far more years experience in these matters and their word should be taken with some respect. but atr the end of the day my opinion is my opinion and not anyone elses. if that's not enough you should buy a collection of boards across the industry and measure their volumes. you will quickly realise that volume is in fact not what you think it is and that the boards will vary from being a higher actual volume then what is stated to a lower actual volume to what is stated and with some about right. all depends on intended use/marketting/brand.
as for your thoughts that surface area has nothing to do with volume..... um.... volume is dependent on surface area. that's very basic maths really. i guess you forgot that.
and your original equation is simply wrong! it appears that you are trying to work out net force. but you incorrectly used gravity and forgot about density. my surface area / displacement comment should have pointed out part of your problem.
your equation should equal 0. as your system is in equalibrium in it's submerged state. no longer sinking etc. to then morph that into an equation on bouyancy is nonsensical.
back to your comment re surface area and bouyancy.
i guess your high school kinda taught you archimedes but didn't teach you to think outside the box.
how you distribute the volume of your board will infact change the surface area and therefore the bouyancy. in so far as bouyancy is refering to "floating objects", which it is in windsurfing and is not bouyant force.
ie. surface area describes bouyancy. bouyancy = weight of displaced fluid.
if you increase the surface area you are increasing the displacement. think of a canoe. floating it has a high bouyancy, submerged it's very small. same on a windsurfer, take the foam from the middle of the board and distribute it to the rails. ignoring "stability" you have now increased the bouyancy. you have increased the surface area in contact with the water and the resultant displacement. yes the area of air now in the middle of the board should be included in the volume but it's not as software only calcs the foam and i don't know a single manufacturer that would include the "air"
so your "new" bouyancy equation which is completely different to your first equation is actually just validating the test method in the pool. congrats. again, i don't care that that's not "real" volume read my comments above re board volumes.
just on your final comments re 117lt wave boards. how many examples would you like me to get??
and have a merry xmas [}:)]
Sideskirt, This is the link to some proper surfers stuff but I just use stuff from the hardware store for sanding gyprock walls.. http://www.shapers.com.au/categories/Surfboard-Sanding-Products/Gauze-Screen/
That last comment was pretty tongue in cheek Gestalt, with your internet experience you should know better than to get offended by anything you read, but to be on the safe side, I will end every sentence with
hey Gestalt,
Keep going - you'll be at 10 000 posts in no time!
I wonder how many hours at the keyboard that translates to?
Have you also considered the different floation qualities of salt versus fresh water?
and on a quieter note, in the news today,
a new form of internet forum is sweeping the globe. this new forum requires uses to not post.
inventor of the new forum concept, Reaction, said "it's a great idea that the kids are really digging, what we do is we create an online community and then we encourage users not to post. in reality it's just a reflection of modern society where members of communities no longer interface."
in other news,
major board manufacturer starboard have announced that this years range of boards are really really really really close to the actual volume stated on the boards. some would even say extremely close.
news today contacted other manufacturers who refused to comment saying they were unaware of the real context of the word volume and were disapointed that their designers hadn't listened at school.
government sources said off record that a full enquiry was being held into why people hadn't finished high school and the true meaning of the word volume.
lol, no need for running. got my lightwind board and it's a cracker
after the quad i'm looking towards a 10'5 wave board and then maybe the 99lt freestylewave.
great board! At least it looks that way, have fun testing, it if you haven't yet :)
