thanks its all comeing to geather now, i was a bit worried about draging out the balls when wetting the core,but im still going to give the divinicell a dry coat of balloons before laminateing the outer layer that stuff is resin hungry besides they increase the density and you need less resin on the laminate, im allso useing a bleeder film

That's good keef, sorry I wasn't following you until Mr Love pointed out you where talking about flotation, not volume.

I also agree that volume isn't all that important, it's handy when there's little wind, but once planning it has no effect.

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decrepit said...

That's good keef, sorry I wasn't following you until Mr Love pointed out you where talking about flotation, not volume.

I also agree that volume isn't all that important, it's handy when there's little wind, but once planning it has no effect.

you mentioned no effect on planing? whatabout average board speed around the course if the winds are powered but not too consistent

I think I stand by what I said, even if you're down to just planning speed, somewhere around 15kt (depending what sort of board you're on), volume doesn't contribute anything, it's all about planning surface shape/area, width and rocker.

ill have to agree with that decrepit, ive got a rrd advantglide 125 L, its 2.45x700and as skinny as and incredabley quick to plane and just hangs in there until its milked the gust dry, smallest sail 6.7 to 8.5 46 fin

i'll be the odd one out i guess.

volume does contribute to planing because it is part of the whole outcome. "lift"

a heavy board definately won't plane as long or as early as a lighter board.

one of the forces involved is bouyant lift.

ive seen large volume boards that are norrow for there volume and they dont seem to work , i tend to think you get the lift from a larger fin and a wide'r board , im sure you get more air under the wider boards thats why the stay on the plane with no apparent wind

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Gestalt said...

i'll be the odd one out i guess.

volume does contribute to planing because it is part of the whole outcome. "lift"

a heavy board definately won't plane as long or as early as a lighter board.

one of the forces involved is bouyant lift.

Im not sure it does Gesty, sure it helps you get on the plane but once there I dont think you need it as much. Like Decrepit says Bottom shape will help you stay there and fin too.

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keef said...

ive seen large volume boards that are norrow for there volume and they dont seem to work , i tend to think you get the lift from a larger fin and a wide'r board , im sure you get more air under the wider boards thats why the stay on the plane with no apparent wind

Keef I think you will find its more that you can carry a bigger fin with the wider boards than the actually width.

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vando said...

Im not sure it does Gesty, sure it helps you get on the plane but once there I dont think you need it as much. Like Decrepit says Bottom shape will help you stay there and fin too.

yeah, i agree with decrepit about width and bottom shape being major players but you can't say volume has no effect.

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Gestalt said...

i'll be the odd one out i guess.

volume does contribute to planing because it is part of the whole outcome. "lift"

a heavy board definately won't plane as long or as early as a lighter board.

one of the forces involved is bouyant lift.

Yes, volume helps to get you on the plane, but once there, there shouldn't be any displacement happening so buoyancy doesn't come into the equation.

Agreed aheavy board isn't going to plane as well as a light board, and what does more volume do?
Add more weight of course!!!!

So if you have board "A"
and an otherwise identical board, except thicker "B"

Then B may get on the plan slightly earlier if the rider is sinking board A to the footstraps. But once the boards are out of the water, to the difference in thickness between them. Then they both have the same displacement, but board B is heavier, so board A is going to plan better!!!!

woe is me the fatty bomboms.

Width doesn't work because of getting air under the board. Air is compressible and viscous so it pretty much just slips away.

Planing happens when the board pushes water particles down as it hits them. As old Isaac said, pushing something down means pushing something up - in this case, the board.

A wide board pushes more water down, so it lifts better. A longer planing surface is less effective, pretty much because by the time the water goes past the "stagnation point" (the front of the planing surface) the water near the board has already been pushed down. Pushing it down more has less effect. The front 25% of the planing surface produces 45% of the lift IIRC. Because the planing effect is more efficient on a wide surface, induced drag drops by the square of the width. Unfortunately, at lower speeds planing lift is less important and what counts are other factors where drag INCREASES by the square of the width, so what works when are planing most of the time doesn't work if you aren't planing most of the time.

It's the same effect that makes wide high-aspect wings and tall high-aspect sails more efficient a lot of the time; from the direction of the "incoming" fluid a Formula board's fat, short shape is actually like a tall, skinny wing.