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

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.

stehsegler said...

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.

yes a board of a certain volume will have different bouyancy because the density of the water is different. same as your board of a certain volume will have different bouyancy if it is heavier or lighter.

for eg. if you take a 100lt board from maker a that is a pro model and weighs 5kg and take a 100lt board from maker b and it is the wood version and weighs 8kg the board from maker a will support 95kg in fresh water and the board from maker b will support 92kg in fresh water. or there abouts not taking into account volume distribution, cohesion or stability.which i am not including on purpose.

where this all stems from is custom makers back in the day realised that volume effected the boards performance. they didn't have computers to calculate volume and didn't have high end volume tanks to calculate volume so the standard method was to place the board in water and load it up with weights and then refer to that as the volume when what it was actually was the weight a board could support or it's bouyancy. some would roughly calculate the volume with basic equations, then check it in the pool with the weights. after a while their experience allowed them to understand what dimensions would create a certain volume which was actually it's bouyancy.

edit* this is also why they started to chase lighter construction methods because they realised that weight effected the bouyancy for a certain volume.

when you went to a shaper to get a board built they would use your weight to get an idea of the bouyancy required and then simplistically referred to it as volume. i think that's why windsurfers in general still confuse the 2 because all of the thoughts on volume, which is actually bouyancy have been carried through.

at some point modern boards were develped by companies that had access to computers or volume test tanks. they started to refer to volume as it was meant to be. but all of the rules of thumb people use to figure out board volume for sailing remained from the days of loading up boards with weights or from the discussion on the beach.

i don't think of my boards by volume. it doesn't really mean anything. i think of them by use.

my lightwind board, my highwind board, my fish, my (soon to be) quad. in the planning i think old school and allow for the weight of the board in the bouyancy and refer to the bouyancy as the volume. not technically correct i know. old habits blah blah....

to be honest i'd rather know the weight a board can take for lightwinds. whe naverage joe walks into a shop and buys a 100lt bard because he weighs 95kg and his rig weighs5kg he's actually undercooking it by the weight of the board which is approx 7-8kg which i would incorrectly refer to as loosing 7-8 liters.

edit* pretty much brings it full circle when starboard started to refer to virtual volume. boards feeling like a certain volume when they were another. people crucifided them for it. but what people were crucifying them for was the bouyancy not the volume. now starboard list volume, weight,ofo tail, ofo nose and thickness. they are the only manufacturer that tries to give the sailor a full understanding of what the board is designed to achieve.

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????

i can't be bothered anymore.

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.

sideskirt said...

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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yep, i'd expect 100+ from those dimensions,, if u go off prod board dimensions....is it wafere thin?

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...

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 [}:)]

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?

jasonc said...

i think you guys need to go for a sail

and remember "Actions speak Volumes"

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.

120 liter waveboard ... go for a jog

great board! At least it looks that way, have fun testing, it if you haven't yet :)