Author Topic: Cheaper and more durable alternative to kenalu Mana paddle?  (Read 3450 times)

jondrums

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Re: Cheaper and more durable alternative to kenalu Mana paddle?
« Reply #30 on: May 14, 2020, 12:49:31 PM »
We are also finding that clean flat water is much easier to pump in than choppy soup that alters the flow over the wing.   

yes, absolutely!  I really don't understand why, but glassy water is for sure easier to maintain a pump. 

A few finer points on this coming from dockstart pumping on flat water (no swell, boat wake, or fetch for wind effects): 

In light wind, just enough to disturb the surface maybe 5-10knots - it seems just a little harder pumping WITH the wind versus AGAINST the wind.  This is confounding and surprising, but I repeated it several times.  I cannot understand why this would possibly be.

Crossing over my own wake 5-10 seconds later is noticeably difficult to maintain pump.

PonoBill

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Re: Cheaper and more durable alternative to kenalu Mana paddle?
« Reply #31 on: May 14, 2020, 04:08:03 PM »
I know! I know! (waving raised hand wildly)

Five kts of surface wind is more than enough to get some wave energy working in the water. If it blows long enough you'll even get some current flow. When you're pumping to get up you're probably going 3mph at best. A 1 mph current or wave energy moving the same direction your pumping in reduces your apparent speed through the water by 30 percent.

We see the same thing on east wind days in the gorge. Going with the current it's much harder to get up, even if the wind is blasting. That's also why it's relatively easy to downwind foil in the gorge. If you're holding still in the 3mph current with 20kts on your back your foil is seeing 3mph worth of lift. 

Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

jondrums

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Re: Cheaper and more durable alternative to kenalu Mana paddle?
« Reply #32 on: May 14, 2020, 06:00:22 PM »
makes total sense, like a when a plane turns 180deg from into the wind to with the wind it will need to substantially increase its ground speed in order to maintain the same stall speed.

SUPdad

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Re: Cheaper and more durable alternative to kenalu Mana paddle?
« Reply #33 on: May 16, 2020, 09:09:49 PM »
makes total sense, like a when a plane turns 180deg from into the wind to with the wind it will need to substantially increase its ground speed in order to maintain the same stall speed.

An airplane doesnít really care which way the wind is blowing. To fly upwind and cover an equivalent amount of distance, this will take more energy. I get what you guys are saying about the apparent loss of forward airspeed (water speed?) when going downwind (which I also assume means moving with the current) and it sort of makes sense to me but sorta does not. Perhaps itís another instance where technique is more optimal for one situation and not the other?

blackeye

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Re: Cheaper and more durable alternative to kenalu Mana paddle?
« Reply #34 on: May 17, 2020, 12:42:50 PM »
makes total sense, like a when a plane turns 180deg from into the wind to with the wind it will need to substantially increase its ground speed in order to maintain the same stall speed.

An airplane doesnít really care which way the wind is blowing.

Agreed, when it's in the air. And same for a board or foil in current.

But there must be something else: maybe it is the lag in needing to accelerate the mass of board and rider in transitioning between up and downwind; maybe it is the foil's movement through the relatively opposite motion of the turbulence Bill describes.

PonoBill

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Re: Cheaper and more durable alternative to kenalu Mana paddle?
« Reply #35 on: May 17, 2020, 03:40:46 PM »
makes total sense, like a when a plane turns 180deg from into the wind to with the wind it will need to substantially increase its ground speed in order to maintain the same stall speed.

An airplane doesnít really care which way the wind is blowing. To fly upwind and cover an equivalent amount of distance, this will take more energy. I get what you guys are saying about the apparent loss of forward airspeed (water speed?) when going downwind (which I also assume means moving with the current) and it sort of makes sense to me but sorta does not. Perhaps itís another instance where technique is more optimal for one situation and not the other?

Umm, WHAT? Of course an airplane is affected by which way the wind is blowing. Its groundspeed is a vector that sums air velocity (the airplanes velocity through the air) and wind velocity.  And at our lower speeds its much more important. If you go straight into a 10 mph wind at 10 mph ground speed the airspeed over a wing or in your face is 20 mph. If you go 10 mph in the same direction as a 10mph wind the wind over the wing or at your back is 0MPH. Note I'm using the terms vector and velocity. Most of what we do is at some angle, so you'd need to use a little trigonometry to do the math. And Velocity is speed in a specific direction.

Same thing for current. If you go 4 mph downcurrent in a 4mph current, the water speed over your wing will be zero. No lift.

Anyone sailing (or winging) should have a clear understanding of apparent wind and current. If you don't, you're going to have some long afternoons trying to get where you want to go.
« Last Edit: May 17, 2020, 03:49:25 PM by PonoBill »
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

jondrums

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Re: Cheaper and more durable alternative to kenalu Mana paddle?
« Reply #36 on: May 17, 2020, 08:10:47 PM »
back on topic, I bought a replacement Mana and KeNalu extended a significant discount as part of their "forever paddle policy".  I couldn't bear the thought of abandoning a paddle I know and love.  And in other news, I cut 3" off the paddle and it seemed totally fine - will take another few inches off and work my way to +1"

SUPdad

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Re: Cheaper and more durable alternative to kenalu Mana paddle?
« Reply #37 on: May 17, 2020, 08:41:43 PM »
makes total sense, like a when a plane turns 180deg from into the wind to with the wind it will need to substantially increase its ground speed in order to maintain the same stall speed.

An airplane doesnít really care which way the wind is blowing. To fly upwind and cover an equivalent amount of distance, this will take more energy. I get what you guys are saying about the apparent loss of forward airspeed (water speed?) when going downwind (which I also assume means moving with the current) and it sort of makes sense to me but sorta does not. Perhaps itís another instance where technique is more optimal for one situation and not the other?

Umm, WHAT? Of course an airplane is affected by which way the wind is blowing. Its groundspeed is a vector that sums air velocity (the airplanes velocity through the air) and wind velocity.  And at our lower speeds its much more important. If you go straight into a 10 mph wind at 10 mph ground speed the airspeed over a wing or in your face is 20 mph. If you go 10 mph in the same direction as a 10mph wind the wind over the wing or at your back is 0MPH. Note I'm using the terms vector and velocity. Most of what we do is at some angle, so you'd need to use a little trigonometry to do the math. And Velocity is speed in a specific direction.

Same thing for current. If you go 4 mph downcurrent in a 4mph current, the water speed over your wing will be zero. No lift.

Anyone sailing (or winging) should have a clear understanding of apparent wind and current. If you don't, you're going to have some long afternoons trying to get where you want to go.

Sorry to have disrupted your thread, jondrums. But, Iíll say it again, an airplane doesnít care which way the wind is blowing in order to fly. I am pretty confident about that. ;D The analogy above, moving 4 mph downwind with a 4 mph current, yes, you have zero airspeed. However, if you were exerting the same energy as when going upwind, you would (or should) be moving faster than 4 mph over the ďgroundĒ when going downwind.

jondrums

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Re: Cheaper and more durable alternative to kenalu Mana paddle?
« Reply #38 on: May 18, 2020, 01:58:32 PM »
In a plane when you fly into a 20knot headwind at 60knots groundspeed, you've got 80knots of airspeed flowing over the wings.  If you execute a 180deg turn without speeding up, you'll be going 60knots groundspeed with a 20 knot tailwind and have 40knots of airspeed flowing over the wings = bad.  A lesson all pilots learn early on in ground school before they even get into a plane.  That's what I was referencing.

Its EXACTLY the same thing I experienced while turning circles pumping in flatwater.  When I'm pumping into the wind and turn around to go the other way, it suddenly seems like I don't have enough lift.  And when I'm going downwind and turn around into the wind, everything seems easy again.  That's because I have to accelerate my "groundspeed" when I turn from upwind to downwind.  It makes perfect sense, but I didn't put it together until PonoBill explained it.

PonoBill

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Re: Cheaper and more durable alternative to kenalu Mana paddle?
« Reply #39 on: May 18, 2020, 05:42:36 PM »
makes total sense, like a when a plane turns 180deg from into the wind to with the wind it will need to substantially increase its ground speed in order to maintain the same stall speed.

An airplane doesnít really care which way the wind is blowing. To fly upwind and cover an equivalent amount of distance, this will take more energy. I get what you guys are saying about the apparent loss of forward airspeed (water speed?) when going downwind (which I also assume means moving with the current) and it sort of makes sense to me but sorta does not. Perhaps itís another instance where technique is more optimal for one situation and not the other?

Umm, WHAT? Of course an airplane is affected by which way the wind is blowing. Its groundspeed is a vector that sums air velocity (the airplanes velocity through the air) and wind velocity.  And at our lower speeds its much more important. If you go straight into a 10 mph wind at 10 mph ground speed the airspeed over a wing or in your face is 20 mph. If you go 10 mph in the same direction as a 10mph wind the wind over the wing or at your back is 0MPH. Note I'm using the terms vector and velocity. Most of what we do is at some angle, so you'd need to use a little trigonometry to do the math. And Velocity is speed in a specific direction.

Same thing for current. If you go 4 mph downcurrent in a 4mph current, the water speed over your wing will be zero. No lift.

Anyone sailing (or winging) should have a clear understanding of apparent wind and current. If you don't, you're going to have some long afternoons trying to get where you want to go.

Sorry to have disrupted your thread, jondrums. But, Iíll say it again, an airplane doesnít care which way the wind is blowing in order to fly. I am pretty confident about that. ;D The analogy above, moving 4 mph downwind with a 4 mph current, yes, you have zero airspeed. However, if you were exerting the same energy as when going upwind, you would (or should) be moving faster than 4 mph over the ďgroundĒ when going downwind.

Well, I can't argue with that kind of confidence, but I'd never ride in an airplane you were flying.
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

SUPdad

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Re: Cheaper and more durable alternative to kenalu Mana paddle?
« Reply #40 on: May 18, 2020, 09:54:30 PM »
In a plane when you fly into a 20knot headwind at 60knots groundspeed, you've got 80knots of airspeed flowing over the wings.  If you execute a 180deg turn without speeding up, you'll be going 60knots groundspeed with a 20 knot tailwind and have 40knots of airspeed flowing over the wings = bad.  A lesson all pilots learn early on in ground school before they even get into a plane.  That's what I was referencing.

Its EXACTLY the same thing I experienced while turning circles pumping in flatwater.  When I'm pumping into the wind and turn around to go the other way, it suddenly seems like I don't have enough lift.  And when I'm going downwind and turn around into the wind, everything seems easy again.  That's because I have to accelerate my "groundspeed" when I turn from upwind to downwind.  It makes perfect sense, but I didn't put it together until PonoBill explained it.

Iím not disputing what youíre experiencing with pumping. I canít even do it in one direction, let alone upwind or downwind. ;D  However, I think the airplane analogy may not be the true explanation for whatís happening. The thrust generated from pumping is something I canít quite wrap my brain around. Perhaps the cadence needs to increase as you turn downwind.

For the airplane theory, I think you have it backwards. Iíll say it again, the airplane cares nothing about ground speed...maybe pilots care about ground speed as it may get them home faster. :o Airspeed is all an airplane is concerned with. I am 110% positive that if youíre in an engine driven airplane, level flight, constant airspeed, if you turn from upwind to downwind you will not fall out of the sky if you donít increase the power. Yes, you will lose a little altitude (or airspeed...your choice) during the turn only with no power increase.

Give this some thought...we all know with a strong tailwind, an airplane flight is shorter. Assuming a given fixed amount of power (and fuel) is used, your argument that you need to increase your speed with a tailwind doesnít make sense. That would imply that you burn more fuel with a tailwind to get from point A to B. Ground speed does change, of course, but if the input power (what energy youíre exerting) doesnít change, it should still work. The energy you exert to pump is difficult to measure as it may be a change in technique rather than some sort of easy to quantify amount of energy.

So, I guess what Iím saying is I think thereís a different explanation for what youíre experiencing. What that is...I have no idea.

Ponobill...better drive next time.  :o
10 mph ground speed into 10 mph wind = 20 mph airspeed
20 mph airspeed with a 10 mph tailwind = 10 mph ground speed
And note that I never said an airplane is not affected by wind. What I said is airspeed is all that matters in order to fly.
« Last Edit: May 18, 2020, 09:58:58 PM by SUPdad »

Kwolfe

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Re: Cheaper and more durable alternative to kenalu Mana paddle?
« Reply #41 on: May 19, 2020, 03:56:09 AM »
I think 20mph airspeed with 10mph tailwind would have you going 30mph ground speed.  This is why the plane ride is shorter with a tail wind.  It's perceived airspeed that is needed to create lift.

Sorry, couldn't leave it alone  ;D

jondrums

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Re: Cheaper and more durable alternative to kenalu Mana paddle?
« Reply #42 on: May 19, 2020, 10:49:25 AM »
Iíll say it again, the airplane cares nothing about ground speed...

You are unfortunately incorrect with this statement.  PonoBill doesn't want to argue, but its my thread so I can - hopefully we can be friendly about it.  Honestly, the concept is a little bit theoretical in general aviation, because in practice, during a long slow 180deg turn the issue is imperceptible.    But it is real, impossible to cheat physics and it does come up in aviation with acrobatic planes.

Ground speed is another way of saying inertia.  A body in motion will maintain that motion except for external forces.   So, when turning from into the wind to with-the-wind, the plane has to increase its inertia (ground speed) to maintain a constant airspeed.    That increase in inertia does take energy, or input from the engine (or in my case, my legs).

SUPdad

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Re: Cheaper and more durable alternative to kenalu Mana paddle?
« Reply #43 on: May 23, 2020, 07:22:23 PM »
I think 20mph airspeed with 10mph tailwind would have you going 30mph ground speed.  This is why the plane ride is shorter with a tail wind.  It's perceived airspeed that is needed to create lift.

Sorry, couldn't leave it alone  ;D

Oops, you are right!  Not paying attention to what Iím writing.  ;D

SUPdad

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Re: Cheaper and more durable alternative to kenalu Mana paddle?
« Reply #44 on: May 23, 2020, 07:42:57 PM »
Iíll say it again, the airplane cares nothing about ground speed...

You are unfortunately incorrect with this statement.  PonoBill doesn't want to argue, but its my thread so I can - hopefully we can be friendly about it.  Honestly, the concept is a little bit theoretical in general aviation, because in practice, during a long slow 180deg turn the issue is imperceptible.    But it is real, impossible to cheat physics and it does come up in aviation with acrobatic planes.

Ground speed is another way of saying inertia.  A body in motion will maintain that motion except for external forces.   So, when turning from into the wind to with-the-wind, the plane has to increase its inertia (ground speed) to maintain a constant airspeed.    That increase in inertia does take energy, or input from the engine (or in my case, my legs).

I have no desire to argue, and of all places on an Internet forum. :o But I think discussion of theory is interesting and occasionally helpful. If feelings get hurt, Iím sorry as that is not my intention. This forum isnít terribly active so why not discuss so we all have things to think about?  I donít know Bill but I know who he is and realize heís a smart guy.  Iíve asked many times here and heís always there to give good advice and Iím thankful for that. Doesnít mean we have to agree on everything though.

As I hinted in my earlier post, I kinda get what youíre saying about the inertia but it also kind of doesnít make sense to me either. For instance, if you were paddling into the current and just stopped paddling. Inertia would keep you moving forward relative to the ground for a bit, and then youíd start drifting with the current. That makes complete sense to me.  However, once you are drifting with the current, no energy is needed to continue motion. So perhaps thereís a little extra energy needed to turn around, but once equal to the current, the energy should be the same as when going into the current?  I dunno...too much physics for me. ;D

Iím going to have to stick to me belief that an airplane doesnít care about the wind, steady state wind, at least. The pilot is usually the one who should be concerned about the effect of wind. Primary flight instruments donít have a ground speed indicator amongst them. ;D And I donít know anything about aerobatic planes...too many forces and vectors and all that.

Anyway, Iím sure what youíve experienced is real and not imagined. Itís just the explanation of it that Iím not satisfied with. So, peace, man...no malicious intentions here...just like to discuss and learn.