Is all that volume neccessary in a race or down wind board?

[SUPflorida]

After you get to a volume that easily supports the riders weight, what, if any, benefit does building a race board that can support 2 to 2-1/2 times the weight of the rider?

With all the talk about how hard it is in to paddle in high wind and rough water you would think that anything over 1-1/2 times would just make a bigger target to be blown around.
So there must be some reason behind it....enlighten me....

[55NSup]

My thinking too. So i am testing thé hypothesis.

[JillRide45]

Ok, I know nothing about shaping or board design.  What I can tell you is my experience on different race/ocean boards.  I had a custom board made that was the lowest volume board I have raced, 12'6" x 26" and thin.  The board paddled really nice in flat water but any chop or boat wake and the board slowed and got very unstable. Wind chop was terrible as I the board would change speed all the time as water washed over it.  I am now paddling a 12'6" x 27" NSP/DC board with a ton of volume for me.  The board is a dream to paddle in the mess. It never seems to be disrupted by boat wakes or chop, just skims over the top. 

My experience is rail shape has more influence on how the board paddles in wind than the volume of the board.  Paddle a Starboard Ace or NSP/DC board in cross chop and compare that to how a BARK paddles in cross wind.  You will immediatly feel the difference.

Jill

[headmount]

Cross chop and DW are two different animals.  The higher volume SIC boards I've owned (F16, 17 Bullet) take off and plane on ocean glides.  It seems to me like volume works in your favor in this situation but in side chop more volume is more challenging.  Volume of course, generally increases with length and length allows the board to roll on a plane longer.  But length gets in the way if the swell frequency is shorter. 

We have a DW run on our southside that seems to favor 14s for the wavelength that is common on that side.  I got to ride my new 14 over there in side offshore conditions and had to angle in across chop to finish.  No gliding at that point.  Board was less stable than longer one (17) in that situation.  So you play with many different variables and no board is perfect all the time.  You go with the percentages.  It's like your wife.  If you get along 80% or more of the time then that is as good as it gets. 

[PonoBill]

I hope not, I have an idea for race boards that will probably eliminate about 30 percent of the volume. But I do think big rails are useful. We'll see.

[supuk]

after trying a large number of race boards dw and surf boards i am convinced that 90% would be better if they had less volume and its the way i have been going. The dw board i have just built i have tried to reduce volume and weight up front to try and help agility, i cant see the point in standing 4" above the waterline when you don't need to . I think there can be a lot of confusion between when volume is needed and when it would be better to change the outline.  Hopefully our flat spell will go soon and i will get to try it out and give a better reprot.

[PonoBill]

Actually, from a paddle efficiency standpoint, the lower you can stand, the better. I tried a board a few years ago that put my feet on the bottom skin. Very fast, but if you fell it was nearly impossible to get back on the board and the footwells weren't self bailing. With some more work it had potential, but the designer gave it up.

[supuk]

yea im not to keen on foot wells however i will be experimenting with them in the future to push the limits for pure flat water designs. I think with a planning style board like like a surf or dw board out line is allot more important than volume, one the board is up and going volume is virtually irrelevant. You only need to step on a wake board or water ski to see how much volume you need to keep you on top of the water once you are moving at just a few mph. I think there are positives and negatives to volume but at the moment from what i have figured im defiantly preferring the lower volume numbers!

[headmount]

For SUSing, you can go as low volume as one is able to stand on but for DW boards you don't have the luxury of a steep wave to get you going.  Our open ocean waves are small and flat by comparison to breaking waves.

So when you say, "once the board is up and going volume is virtually irrelevant" that's being fairly cavalier with the up and going part.  Catching glides isn't always easy, in fact sometimes it's bust ass difficult and that volume helps heaps when you're trying to get in.   

But IMO less board weight seems to help with the inertia to enter planning speeds.  My new 14 is over ten pounds less than my 17 and definitely releases quicker.  The 14 is 267 liters according to SIC.  Don't know the volume on my 17 but once it's rolling, it rolls farther than the 14. 

IMO so much depends on the conditions you're riding.  Here on high wind Maui, many board ideas have been tried and the higher volume boards seem to work better than the less.  But non-planning conditions ??

[supuk]

for the volume to be of any real use it has to be under water and i know for myself from thin 12'6 race boards the only time i sink the tail is in turns. At 72-75kg which is probably a fairly average weight in the uk for a paddler on most 14 dw boards i have to get super far back before i can get the tail anywhere close to sinking. by up and going i don't mean on full plain, it was only the other day i was on my 7'4 paddling back from a point when a friend commented on how as soon as i got a tinny push from some thing the board would come up  and no longer be submerged. I would love to take a few of the top boards and leave the bottom as is but go to town on re shaping the deck and reducing volume.

[JF808]

I agree with Headmount and IMHO, the board planes better with more volume, and like headmount said I think speeds are an important factor.  for head high SUS you'll see faster initial speeds so you can get away with a thinner board and less volume, take that same board on a ankle slapper day and now your not throwing as much tail! Now a higher volume SUS board or downwind board on that same ankle slapper day and i'm sure you'd get on that small wave and glide

[DavidJohn]

"Re: Is all that volume neccessary in a race or down wind board?"

IMO .. Yes.. Very necessary .. I sometimes wish there was a bit more.. and it has nothing to do with the paddlers weight.. or for stability.

DJ

[SUPflorida]

DJ....if not for weight or stability...what is the reason as you see it?

From a strictly logical approach ....higher volume means your standing higher off the water/higher center of gravity/less stability/ unless its a sunken deck....you have greater volume which means more weight in foam & glass. You have greater surface area effected by wind which on any heading other than straight into the wind/straight down wind you have weather cocking to contend with.

So far I'm just not seeing any justification other than thicker is an easy/cheap way to make a board stiffer all other things being equal.

[DavidJohn]

IMO.. The reason it's there.. and needs to be there.. is all about drag.. and on a DW board.. less drag helps to get you planning.. Waves flow along the side of the board.. I see it in my DW vids.. A thick rail or tail prevents water flowing onto the deck or getting sucked around the rails.. Any water that flows over the deck causes a huge amount of drag.. Windsurfers will know the feeling of planning and not planning.. When you water start or drop off the plane the water flows over the deck.. Once you start moving forward fast enough that the water suddenly releases from the edge the sudden acceleration is amazing.. I often think that a big part of the reason an Ace is so fast is that tall tail shape that prevents any water sucking around the rails and over the deck or tail area like other boards.. It makes me laugh when I hear people say that the new Starboard Allstars have a big thick chunky tail shape so it will float bigger people and the funniest thing I often hear is when they say the tail is like that so it can get a push from the wave coming up behind you on a downwinder.. What are these guys thinking... These thick tails also let you get back on the board to surf a runner or to do a kick turn without having too much water flow over the deck.. Maybe I'm wrong here but it's what I think.

DJ

[Blue crab]

I agree with the consensus that volume is really helpful but the question is why.  I am trying to deconstruct this by using physics courses from my distance past. It seems to me that 3 things determine whether a board planes. First is the speed going into the wave. This is Newton's first law. It also explains why elite DW racers who can manage the balance issues use 23" toothpicks as race boards.  My experience using a Javelin in DW conditions is that it requires precious less effort to get into bumps... just one or two hard paddles  (We can have another post about the physics of climbing back on the board innumerable times).  The inherent flat water speed of the board is probably indirectly related to volume but more so to hydrodynamic specifics of shape such as the hull, rails, tail etc...

The second issue is gravity.  The steeper the bump, the greater the probability of the board releasing for a nice long glide.  I try to capitalize on this by moving forward on the board at the very beginning of a glide to fulcrum the board "downhill".  Gravity has nothing to do with volume, and is purely an effect of mass.  For this reason, it surprised me at first that carbon boards are faster in DW conditions. More mass (weight) would appear to favor heavier boards if gravity were the driving factor (see below).

This leads to the 3rd issue which is friction or drag.  This is where my physics gets pretty hazy.  However, what I recall is this... the less surface area in contact with the water, the less friction and the greater the potential to plane across the water.  This includes the nose and rails. As DJ points out, water on the top of the board is probably the greatest potential source of drag. The large / steep rails and surfy noses of DW boards help by limiting the surface area in contact with the water. Lighter boards are theoretically more buoyant, provided the rider is not too heavy, and so the rails are even less submerged.... thus, less drag.  On DW boards, there appears to be a sweet spot depending on the steepness of the bump, where the board is perfectly parallel to the slope of the wave. The nose and tail are not dug in, and the board just flies.

This leads to my final point which is more "right brain". Much as it feels cool to carve through flat water on a Bark or Starboard, I think the feeling of floating a few inches above the water in DW conditions (on a Naish or SIC) is superior to being in a recessed deck, even if this comes at the expense of stability.