Author Topic: Scientific Flatwater Board Testing 101  (Read 27464 times)

Eagle

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Re: Scientific Flatwater Board Testing 101
« Reply #45 on: June 23, 2016, 09:03:35 PM »
Here are some comments about planing boards and sub-planing -

"Whereas the planing hull - the goal is to have the water go underneath the board and create lift.  So a planing hull will be faster to get on a plane and be faster once its released from the water and kind of gliding over the surface.  Which that kind of speed is only achievable if you have bumps that push you to get you up to that planing speed."

"sub-planing speeds"

https://youtu.be/Pe3UM0XNchY
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PonoBill

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Re: Scientific Flatwater Board Testing 101
« Reply #46 on: June 23, 2016, 09:18:15 PM »
Sorry, can't help you with any of that. These terms are specific, they don't get redefined because someone wants to sell a board. Those boards are not planing. Anyone who has windsurfed, sailed a planing hull boat, or driven a planing hull powerboat has a strong notion of exactly what planing is. It's not when you're pushing along with 3/4 of the board in the water and the tail buried with water flowing over it. When the board reaches planing speed, it lifts and the tail releases, Water moves under it in a V shape, being tossed to either side. There's no longer contact with a bow wave, the board is being lifted and it's bouyancy no longer matters.

We don't do that except on very rare occasion. I doubt your downwinding conditions exceed mine, or that your experience in doing it is long or as varied as mine. But I'm not the last word in any of that, and what I've experienced doesn't matter any more than what you have. It's just basic hydrodynamics, and the well-travelled understanding and research behind it all says the same thing. You won't find anyone with even a basic understanding who says anything different.

I agree with Robert that rocker is what distigushes a good downwind board from a flatwater racing board, but planing has nothing to do with it. In fact it's exactly the opposite. Rocker enables the board to stay in contact with the swell more uniformly, and helps transfer energy. If you wanted to plane you'd need some sort of step, and rocker would be your enemy. The tail rocker of a SUP virtually guarantees that it won't plane. Look at any modern windsurfer and you'll see what a planing hull looks like--nothing like a SUP.

Some hulls can be driven with power and speed well above an expected planing speed and never achieve planing. For example, hobie cats, and for that matter most racing catamarans, never plane.
« Last Edit: June 23, 2016, 09:32:39 PM by PonoBill »
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Eagle

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Re: Scientific Flatwater Board Testing 101
« Reply #47 on: June 23, 2016, 09:48:46 PM »
We have windsurfed - sailed a planing hulled boat - and driven a planing hull powerboat.  At planing speeds.

And have a clear understanding of planing vs max displacement speed.  Those boards in the vid look to be semi-planing.  But unless you have ever planed a DW board - it will be hard to imagine unless you see it or experience it first hand.

1     Displacement
2     Semi-displacement (semi-planing)
3     Planing

All are very well defined specific terms anyone can look up.  But it seems the issue of strength to weight may be the underlying sticking point as previously noted.  As without the required ratio - even semi-planing is not possible - let alone full planing.

Sounds like unless you see it for yourself - you will remain unconvinced.  So if you are up to it - come on up and check out semi-planing and planing up north.
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PonoBill

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Re: Scientific Flatwater Board Testing 101
« Reply #48 on: June 23, 2016, 09:52:21 PM »
Okay, I give, you're planing. Whatever,
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Area 10

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Re: Scientific Flatwater Board Testing 101
« Reply #49 on: June 24, 2016, 02:34:39 AM »
Are you guys just arguing about what term to use for a particular experience in the water? We've had many discussions on this forum over the years where people use the same terms to mean different things.

When you are surfing a wave, ie. actually on the wave face and moving up and down doing cutbacks etc, is that planing? Because if it is, there are certainly times when we do that when we are downwinding where I DW. The experience is indistinguishable from surfing: you are on the tail with most of the board out of the water and are travelling faster than the bump you are on, and indeed can move from your bump right over the one in front and into another trough altogether. There is a sudden surge of speed and the sensation is of falling down the trough, with predicable consequences if you don't angle the board quickly.

There are also other downwind bump-riding experiences, such as where you are sitting high on the face of the trough, almost sitting atop it, and are getting carried along with the bump. You don't have to paddle to make progress but your speed is never any faster than the bump you are on. If two of you are on bumps one behind the other, you travel at the same speed - faster than either of you could paddle in flat water (unless maybe you are Connor in a sprint) but not making any ground on each other. When you are bump-riding this way it is not possible to move from your trough to the one in front.

I guess that in my mind I call the first experience "downwind surfing" and the second "bump-riding". But is the first what Eagle is calling "planing" and the second what PB is describing in Rigg's video as "gliding"?

In some very short period steep downwind conditions, and on some boards, nearly all forward progress is through "downwind surfing" - it's a constant stop-start process. In some more regular conditions and with different boards, forward progress can be mostly or virtually all through bump-riding.

As for planing in flat water, under one's own power, I've never had any experience that I can equate with surfing a wave, even for a nanosecond. But then I'm not Connor or Danny. Although what they are doing doesn't look to my untrained eye like a stone skipping on the surface of water, which is what I'd think planing in flat water would look like.

But as I say, I know about the proper hydrodynamic terms for these experiences. I'm not sure we even need them to adequately discuss aspects of our paddling and the designs of boards. We can invent our own terms (which in many ways already seems to be happening). Then there might be less confusion.
« Last Edit: June 24, 2016, 02:39:11 AM by Area 10 »

Area 10

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Re: Scientific Flatwater Board Testing 101
« Reply #50 on: June 24, 2016, 02:58:11 AM »
Oh, and by he way, since the UK has just voted in a referendum today to leave the European Union, our currency has predictably crashed. So now SUPs are going to be even more crazily expensive here than they ever were. I feel very sorry for the SUP retailers and distributors in this country because they aren't going to be selling many boards in 2017 at this rate. The knock-on effect for the euro and strengthening of the Chinese currency in consequence may also affect board prices more broadly across Europe. Some board brands may have to move their centre of operations out of the UK in order to remain in contact with the rest of Europe - although there are rumours of other countries maybe following suit (eg. Holland) in having an in-out referendum too, so no-one is taking any bets on what will happen to the European dream right now. It's a momentous political, social and economic change and is very likely to impact on the business of SUP for us locally. It didn't help at all that Obama came over here a few weeks ago and told us that we must not leave and threatened us that if we did the US would put us on the naughty step. The UK population sympathetic to leaving basically instantly raised two fingers metaphorically (or maybe one middle digit if they originally came from the US) and told him to go forth and multiply, renewed in their resolve to sever as many ties with their allies as they could.

Anyway, I digress... And the people who voted for the exit from the EU were probably those who couldn't afford a SUP before anyway.

Eagle

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Re: Scientific Flatwater Board Testing 101
« Reply #51 on: June 24, 2016, 06:41:20 AM »
Your examples of surfing a wave and gliding are what we would expect and define as well.

Planing is when your board unsticks and catapults forward due to the wave behind pushing you - and you time the push by planting and pulling yourself forward with max force.  Akin to what Connor talks about on a skateboard - at the force needed for Kai to get his board up and foiling.  It is a huge amount of pull.  And why we use our 114 blade.  Size matters - as with a small blade you just cannot generate enough pull in a few tap tap tap strokes.

The force needed is explosive - and a sudden friction reduction occurs as you drop down the wave.  To get on plane you need to get over the buoyancy hump.  It requires proper timing and unweighting.  You need to step back to get the nose up so you can use the lift to plane.  The board then skips over the water as I describe on marbles.  Control is lost momentarily as the board planes.  The Bullets V1 and V2 plane faster and easier than the M-14 - as the rocker on the M-14 is huge.

So kinda like doing a muscle up.  Some people can maybe do a few pull-ups where their eyes barely get over the bar.  Some cannot even do one.  Others can pull up to their chest easily for reps - but never can time and explode to achieve a muscle up.  The sticking point is similar in planing.  Whereas in a muscle up it is the chicken wing transition - on a board to plane it is unsticking and launching forward with lift.  I can do muscle ups for reps easily - my wife cannot do one pull-up.  That is the strength to weight difference - it is really quite substantial.

Any less of a launch results in semi-planing.  We semi-plane a lot as we jump to the waves ahead.  The waves behind never catch up to us.  We always move forward.  And we look for the biggest cresting swells ahead - and semi-plane up to them.  They may be 5 or 6 waves ahead to the left or right.  We chase them down - and use that big one to plane off.  Within a run of an hour or so - we will plane about 5 times in winds about 20 kts.  When winds jack up to 25+ we plane a lot.  At those times - winds in Squamish create smaller waves as they bomb down a mountain.  So the fetch is very short - but the wind is high.  The windsurfers and kiters and foilers love that.  Whitecaps and spindrift are everywhere.  On a board - that is planing nirvana.

Upon entering Squamish - water shallows and the waves build in size.  In this steep and deep environment planing becomes a lot more difficult as the deep wave troughs slow you.  So best to go into glide mode at the speed of the swells and glide upriver.

A10 - hope you guys come out of it ok.  But a huge change for sure.  We went through Quebec wanting to separate years ago - so have some idea of the how a country can divide - as well as unite.
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Pierre

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Re: Scientific Flatwater Board Testing 101
« Reply #52 on: June 24, 2016, 08:02:23 AM »
I think I misunderstood Ponobill's explanation a bit,  but the topic is flat water test, hope we will see positive output.
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PonoBill

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Re: Scientific Flatwater Board Testing 101
« Reply #53 on: June 24, 2016, 11:38:35 AM »
A10--yes, it's semantics, but the title of the thread is Scientific Flatwater Board Testing 101, which presumes some rigor. People use terms loosely all the time, and I know that few people want a lecture from a geek that paddles don't cavitate and neither do fins. Boards don't plane until lift is greater than buoyancy, blah, blah. They're the wrong word to describe the phenomenon because it has a specific meaning. And I realize words get appropriated all the time--mathematicians and physicists use common words to label thing that are wildly different from what people assume they mean, like "color" for quarks, or they make up words, like heteroscedasticity.

But in this thread I'd assume we're supposed to be a bit scientific, and talking about SUP boards having a planing hull is just nonsense. If they ever do plane (lift greater than buoyancy) it's an accident. The mental visualization for "is it planing" is simple. Picture the board that's supposed to be planing. Replace it with a flat slab with zero buoyancy. See if you can imagine it being still above water at the speed it's traveling with the motor it's got. Surfboards don't plane going down the face of a wave. They are designed expressly not to. You don't see super wide, totally flat tails on surfboards. That's what a planing hull looks like. If you've ever tried to surf a sail-less windsurfer you know how much they suck at it. the wide flat tail won't catch a wave.  Big wave gun? Planing? Never. Skipping like a stone? Sure. Turning across the face of the wave is a grey area. Riding the rail, most of the board out of the water. Smells like planing, might be, probably isn't. If the rail isn't dug in along it's length you're a passenger. Bob Simmons used to rant about this. Not a new issue. So yeah. maybe a wide tail simmons shape with straight rails, light weight, minimal float, zero tail rocker--that might be planing when it's maxed out, but even Simmons thought not. He thought with that much rail and that much width that buoyancy was probably still dominant. You want to plane, get a Paipo board.

If you want to know if you're planing or not, point your gopro at the tail. If the water is curling up the rails it ain't planing, if it's flinging out, you are. Let's see the pics.

But I'm not going to educate anyone, and most people don't care about this stuff. If you care, read up on this a bit. It's been an important issue in naval architecture and later in board design for the last 50 years. Of all the boards I can picture planing, a 25" wide, pintail 14' downwind board with continuous tail rocker is the second least likely candidate. Right behind an inflatable.
« Last Edit: June 24, 2016, 12:03:14 PM by PonoBill »
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Area 10

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Re: Scientific Flatwater Board Testing 101
« Reply #54 on: June 24, 2016, 12:15:41 PM »
PB - well I'm a jobbing scientist, so I get used to people using the wrong terminology all the time. You can either get irritated by it (which I spent the first 20 years of my career doing) and lecture the person, or you can ask instead what it is that they are trying to communicate to you. Often, there might not be a perfect term for what they are describing. And this might be the case here. If we don't use the term "planing" then what term do we use to describe what is happening when we are full-on surfing a bump at, say, 15 mph? Very probably there is a good term for it. But if you used it no-one would know what you are talking about.

A good recent example is the use of the term "Ventral fin" that Larry Allison invented to refer to a fin that is placed forward of the standing area. "Ventral" is an anatomical term that most commonly means underside. So all fins are ventral fins, otherwise they wouldn't be sticking in the water. It would have made more sense for him to call them "anterior fins" or somesuch. Of course, I pointed this out on this forum, and everyone agreed, but here we all are now a couple of years later talking about "ventral fins" nevertheless.  So I guess it doesn't matter much since we all understand what we mean, even if it would seem bonkers to many other people who use this term in other (original) contexts.

Anyway, I might use the term "planing" hull (vs. "displacement") because that's what everyone else uses, even if it never actually planes in a true scientific sense. But if you have suggestions for a better term then let's hear them and maybe the SUP world will start adopting them. As for the downwind experience, well, I'm happy distinguishing between "gliding" and "surfing" a bump, when the latter describes travelling faster than the bump you started out on, and the former when you are just travelling with the bump. And as for flat water, well personally I can't really see any reason to think about planing in that context, magical though it is what people like Connor manage to do with the board. I think of that more like unweighting the board through a combination of transferring weight to the paddle and a movement of doing a kind of "standing crunch". But I'm willing to be educated, and I love to learn new words.

PonoBill

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Re: Scientific Flatwater Board Testing 101
« Reply #55 on: June 24, 2016, 01:28:53 PM »
I don't really have one, glide works best for me, but it's a fuzzy notion. To me Glide denotes the energy transfer between board and swell or board and flatwater. There might be a technical term for it, but I don't know it. In downwinders, if you're going the right speed and your hull is appropriately shaped, you can transfer a lot more energy over a longer period of time and gain/maintain more speed. In flatwater, glide is just the coastdown deceleration, and if you don't weigh much, and your hull is efficient for the speed you start with, you coast down more slowly.
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Eagle

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Re: Scientific Flatwater Board Testing 101
« Reply #56 on: June 24, 2016, 01:47:43 PM »
Glide works best for you - but is a fuzzy notion - interesting. 

Maybe Robert and all other SUP retailers should call their non-displacement boards "glide" boards then.

It would seem that the yachting world also should replace the word "semi-displacement (and semi-planing) hulls" - used for ages - to "glide" hulls since these words are not true words - but only made up for marketing purposes.  Please!  ;D

{If we don't use the term "planing" then what term do we use to describe what is happening when we are full-on surfing a bump at, say, 15 mph?}  Gliding at 15 mph.  Yes I'm gliding at 15 mph then!   ;D
« Last Edit: June 24, 2016, 01:59:37 PM by Eagle »
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PonoBill

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Re: Scientific Flatwater Board Testing 101
« Reply #57 on: June 24, 2016, 03:20:05 PM »
Gliding might be fuzzy, but planing is not. Planing is a specific term for a transition. From buoyancy to lift. Like rolling to flying. If you want to say you're partially flying if you run along flapping your arms, please do so.

I refer you once again to the title of this thread. I'm not trying to get Robert and everyone else to stop using the term, I don't really care. I'm simply making the point that we don't plane.
« Last Edit: June 24, 2016, 03:24:14 PM by PonoBill »
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Eagle

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Re: Scientific Flatwater Board Testing 101
« Reply #58 on: June 24, 2016, 03:54:28 PM »
I understood your position on "planing" and the non-word "semi-planing" from the get go.  Straw man and red herrings aside.

"There might be a technical term for it, but I don't know it."

Again - this is the technical term you are looking for - pre-googled for you.  Please check out any of the links and you will find the term.  There is a word in fact that fits between displacement and planing.  It is an actual occurrence - and it is ok.  Our ULDB is a semi-displacement semi-planing hull.  And we have planed that boat during races at 18 kts GPS.  And 15 kts and 10 kts etc.  At the lower speeds we are semi-planing not gliding!

https://www.google.ca/search?sclient=tablet-gws&site=webhp&source=hp&q=semi+planing+hull&oq=semi+planing&gs_l=tablet-gws.1.0.0l2j0i22i30.2391.6618.0.8757.12.10.0.2.2.0.145.867.7j3.10.0....0...1c.1.64.tablet-gws..0.12.879...0i131j0i10._mpqccLslZY

But hey - as noted I am perfectly ok with "gliding" at 15 mph as well.  I love gliding along at 15 mph moving forward quickly from swell to swell.

Yeah - everybody at Jaws must be gliding at 30 mph.  Check.

If SUP boards and you do not plane - and you don't really care - why continue to post nonsense.  Seems like you are telling everyone the term planing is nonsense as it relates to SUP - as according to you - they do not plane nor semi-plane - but glide!  Only one term is available to you "glide".  Got it.

Back to regular programming please!   ;D
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LaPerouseBay

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Re: Scientific Flatwater Board Testing 101
« Reply #59 on: June 24, 2016, 04:49:10 PM »


If you want to know if you're planing or not, point your gopro at the tail. If the water is curling up the rails it ain't planing, if it's flinging out, you are. Let's see the pics.

     

How ironic.  The master of spin wants lab results.   

I don't care what anyone calls it, Jeremy is zooming pretty good.
 
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