Will it Plane?

[PonoBill]

That's absolutely true, and what I've been explaining. When lift exceeds bouyancy you are planing. Period. That's a transition, not something you can creep up on. it either does, and you climb over the bow wave, or it doesn't, and you stay on the downhill side.

The reason most surfboards and downwind boards don't plane is because they were never designed to. In fact most surfboards are designed explicitly not to plane. If you are taking energy from the wave (as we do) and you start planing, you can no longer take much energy from the wave. The contact point is too small and the skin friction is too low. Takes a lot less energy to keep them going, so if you approach the design very carefully, as Sims did, or if you toss out the requirement of gathering energy from the wave, as tow-in boards and windsurfers do, then you don't need it. But if you want power and control and your only energy source is a wave (and a weenie paddle putting out 300 watts) then you design them NOT to plane. You put a bunch of rocker in, and shape the rails to fit the wave, stay buried, and complement the bottom shape.

[mrbig]

This may do it..

www.statsmakemecry.com/smmctheblog/confusing-stats-terms-explained-heteroscedasticity-heteroske.html

[PonoBill]

That article's explanation of Froude limits is faulty though. I've never seen a serious paper or book about hull design that treats the effects of wave resistance as a limit other than really archaic stuff. It's long been understood that other hull characteristics, most notably the ratio of waterline length to beam, flatten the curve of wave resistance. Long narrow hulls go substantially faster than their limit. But they also don't generally plane because the lifting force is reduced by the same mechanism that mitigates the effect of wave resistance.

[Pierre]

Skipping. and you might be surprised to know that a skipping rock doesn't skip on one surface in the water--it doesn't "plane" at all. The trailing edge hits first and pivots the rock over, then the leading edge catches and throws the rock clear of the surface. It drills a cavity in the surface and then rises up the steep face of the cavity.  It flips over with each skip. Probably not what you think of as planing, though in the video they use that term. Oh well. High speed rock video at 1:30.

Here's a little paper on it: http://arxiv.org/PS_cache/physics/pdf/0210/0210015v1.pdf and a video:

years ago I succeeded to make a very flat stone plane... but this video gives ideas about taking advantages from the weight change during paddle strokes.... foils and new paddle designs?... search is always opened.

[yugi]

In one word, a word that everyone in the SUP community would recognize and understand, how would you describe board speeds exceeding displacement speed?   

Hell, I don’t know Bean, I’m not in charge of names. If I were we certainly wouldn’t call these boards and what we do SUP. I never say that. Call it Beaning. Flatwater boards exceed “displacement speed” by which I assume you mean the froude “limit”—that’s not called anything special, but from now on we can call it beaning. Catamarans go a lot faster than “displacement speed”.  they Bean like crazy. That makes a lot more sense to me than incorrectly using a word that already has a specific mean throughout the water environment.

…

Sold!

That’s it. Next time you see me take off on a wave I’ll make sure to be screaming “I’m beaningggggg!”.

It’s going to work great at cocktail parties too when a chick ask’s me what I’m into. “Beaning”. This is going to be fun. Plenty of material to work with. I probably will never get to my  “Ti fetish” cocktail conversation. I do have a Ti fetish, my mountain bike hardtail being titanium kitted out with lots of Ti parts.

“Beaning” had a whole different meaning between buddies to what kids are using it for now:
   http://www.urbandictionary.com/define.php?term=beaning
But I can roll with those.

[yugi]

...
 I can tell people I was at the lake beaning the Cat 

I don't have a cat. So I'm looking for a cat to bean.

[yugi]

Skipping. and you might be surprised to know that a skipping rock doesn’t skip on one surface in the water—it doesn’t “plane” at all. The trailing edge hits first and pivots the rock over, then the leading edge catches and throws the rock clear of the surface. It flips over with each skip. Probably not what you think of as planing.

OK, so let’s say the rock is skipping, not planing (it does not however flip over with each skip). What about the skim boarder, what do you call that?

I haven’t seen skim boarders do flips yet. But I’m sure I will before I’m 60.

I haven’t done any skimboard flips myself. But on water I’ll still try anything. On land my jumping and flips days are over. I’m more into beaning now.

[PonoBill]

Maybe this thread does have a purpose.

[yugi]

That’s absolutely true, and what I’ve been explaining. When lift exceeds bouyancy you are planing. Period. That’s a transition, not something you can creep up on. it either does, and you climb over the bow wave, or it doesn’t, and you stay on the downhill side.

The reason most surfboards and downwind boards don’t plane is because they were never designed to. In fact most surfboards are designed explicitly not to plane. If you are taking energy from the wave (as we do) and you start planing, you can no longer take much energy from the wave. The contact point is too small and the skin friction is too low. Takes a lot less energy to keep them going, so if you approach the design very carefully, as Sims did, or if you toss out the requirement of gathering energy from the wave, as tow-in boards and windsurfers do, then you don’t need it. But if you want power and control and your only energy source is a wave (and a weenie paddle putting out 300 watts) then you design them NOT to plane. You put a bunch of rocker in, and shape the rails to fit the wave, stay buried, and complement the bottom shape.

Agree, and disagree.

I think you just opened the door to exactly what I was thinking is missing in this debate. A surfboard on a wave is clearly a situation where lift exceeds bouyancy, right? It’s just that it is designed to be an inefficient plane.

I’m not sure if we are talking about efficiency of planing? Do inefficient planes qualify as planing.

I’m old enough to have planed a Soling. Yes, they plane, even if it ends up something like this…
   
Are Solings efficient at planing? No. Can they plane? Yes.
I’ve planed my [iggy] Naish 11’4 Nalu (rocker!!!) w a sail. OK, both feet were on the fin and 10’ of board was on the air.
Is my Nalu efficient at planing? No. Can it plane? Yes.
I’ve planed on a table top. Wonderfully efficient at planing. When the front edge catches however - it's over very quickly.

Some hulls plane efficiently, some don’t. By design we sometimes want things to plane efficiently, like a formula windsurfer. By design we sometimes want things to plane less efficiently like a windsurf board that’ll perform better in chop, and loads of other examples like SUP boards, gun surfboards, etc etc.

I’ve driven all kinds of boats for wake boarding for  over 30 years (OMG, I’m dating myself and, yes, Tony Finn is a friend). Waterski boats, before wake boarding, were optimised to have no wakes. They planed quick and left no wake. Think formula windsurf board. Wakeboarderss want a wake so you need to make the craft perfectly inefficient. So it’s kind of just on that cusp of planing which we speak about. Before wakeboard boats we’d be on the throttle just keeping the boat just, but almost not, on a plane. Thing is if it falls off a plane the speed drops dramatically so the boarders drops of his/her plane too. So the trick is to maintain that just, but really inefficient plane. As far as I feel it the wakeboard boat is on a plane. Even if a shitty one. I know that cusp really well. One knows when one is up on top of the water and when one falls off it. Every planer knows this feeling.

So the question is: is an inefficient plane still planing or is it beaning? The first part of your quoted material, Pono, suggests it’s planing. My experience on all kinds of planing craft is the feeling of planing does correspond to the bow wave meeting the stern wave to create but one wave. That wave is huge if the plane is inefficient.

Is beaning technically not planing or just shitty planing?

I though my purpose in life was planing. But am happy if in fact it was beaning all along.

PS
[edit to add]: oh! and I’m laser sailor too. When you look at craft today, lasers are hardly the best planing craft around. They definitly just bean. Finn’s even less efficient planers. Yet cool to see that on America’s Cup superfoiling winner, Oracle; of the command core of 3, one is a Laser sailor and the other a Finn sailor (Tom Slingsby and Ben Ainsly). Oh, and Jimmy Spithill a pretty good DW paddler. Beaning rules!

[PonoBill]

Wow, very cool Yugi. That's the kind of thinking I'm looking for. I didn't think of it that way, I just looked at how narrow a planing surface continuous rocker provides (approaching zero at the theoretical limit) and dismissed the idea of inefficient planing. I think for long DW boards with rocker designed to be efficient at coupling the board to swell energy that the feeling people describe as planing is much more a factor of efficiently connecting the hull to the energy available. You get the best and fastest glide when the board is getting pushed hard by the swell. If the board came to a true plane then the energy transferred from the swell drops quickly to nearly nothing. Most of us have felt a DW board accelerate as we turn into the wave on the bottom of the swell. Obviously the vector angle accounts for a lot of that acceleration, but the better coupling of hull shape to swell energy accounts for the extra power required to stay in the swell.

I think the article Robert (Blue Planet) cited is really talking about inefficiency as well. Catamarans can go like blazes with what looks like pure displacement mode--the hull is pushed firmly into the water with the bow and stern waves totally separate. In fact if the bow and stern waves get anywhere near each other it's a disaster. But the other raised hull and the torque of the sail being halfway between the hulls is what's keeping the hull planted. Well, that and the round cross section and rocker. Forced inefficiency--Beaning.

Bean, you might just become famous.

[Bean]

Bean, you might just become famous.

Now you're sounding more like PonoBilly the Kid!

[Pierre]

Planing mode is when the amount of fun is predominant to the amount of effort... Am I right?

[Beasho]

Some interesting stuff here.  I like the curve/push theory.  However we have omitted the 'Inclined Plane' and what this does to the physics as the wave builds and the ability to PLANE efficiently or not (remember the term 'plane' just means FLAT something we would all agree helps to plane). The surging wave actually lifts us UP causing an incline for us to FALL DOWN and move horizontally.  We can never outrun this source of power as long as the wave provides the incline. 

Realizing that there is a massive difference between a sailboat, downwinding and wave riding.  Bill suggested that you might tap out the energy of a wave.  I would suggest otherwise (you could be talking about downwinding where I suppose you could crush the wave).  Look at the picture below and imagine how you could tap this out.  Also note the angles involved.  Nothing like an extreme to make the point.

Someone suggested running the numbers, I have taken the opportunity to show what happens with a 10 degree incline.  For every 100 lbs you weigh there will 17 lbs of Gravity Pulling you vs. just 98.5 lbs of Force normal to the face of the wave.

When the angle increases to 45 degrees, like where Jamie Mitchell is running over Haley, the vector of the board + rider normal to the face of the wave is equal to the horizontal pull down the face.  Think 1:1 Weight to thrust ratio like a Tesla in insane mode.  100 lbs of weight --> 71 lbs of Pull vs. 71 lbs of support (lift) from the water.

2 Observations:
1) As the incline increase our available THRUST increases delivering speed used to counteract drag whether displacement or hyrdrostatic
2) As the incline increases our Normal vector (effective weight on the water) DECREASES lowering the necessary displacement or hyrdrostatic lift.

More exciting are the implications to FOILS.  Because foils have an even lower drag profile than a displacement or planing hulls.  The challenge is binary rather than the transition from displacement to planing.  A 'wing' with a 10:1 lift to drag ratio would be considered pretty antiquated.  BUT it only takes a 6 degree incline to provide the necessary Lift to Thrust ratio.  Starts to explain those crazy small, unbroken waves those kids are riding in other posts.

[blueplanetsurf]

So we agree that a flat bottom will create more lift and gets on plane earlier.
 
I think we also agree that as long as the board is moving, lift is generated by both displacement and dynamic lift.  When a speed is reached where the board is supported predominatley by hydrostatic lift, it lifts, starts skimming on the surface and drag and wetted surface are reduced as the rails are no longer touching the water.  Ok, I'll call this state Beaning because I think sub-planing is a BS term. 

If you continue going faster, like when you are dropping into Mavericks, the board will at some point actually plane, even by Bill's definition, even if it has rocker and is not a Simmons boards, or a skim board. 

The face of a wave or a bump is not flat and I'm thinking a rocker line that closely matches the curvature of the water could actually create more lift than a flat, non rockered surface, which might be why a flat board without any rocker sucks on a wave, it might create a lot of lift in the tail but you can't fit it into the curve of the wave, so it actually creates more drag than a rocker that matches the wave shape, even if you are not turning on the wave.

I have been thinking more about the text I linked to earlier and how he says that lift is always created by both displacement and hydrostatic lift, even when you are planing.  Basically the weight of the rider still pushes down the water and displaces water even when you are planing on the surface.  When you look at the skim boarder he is clearly creating a big hole in the water, displacing the water.  So even though we can agree that he is planing, he is also displacing water, right? 

[TallDude]

What are you guys talking about?  He's skimming.........