Author Topic: review of the Ke Nalu (Pono Bill) paddle  (Read 551904 times)

PonoBill

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Re: review of the Ke Nalu (Pono Bill) paddle
« Reply #450 on: March 26, 2012, 11:24:57 AM »
We'll consider an intermediate jump, but the molds are really expensive and I'm not sure that area change is the issue. The Wiki blades are extremely light. The Maliko blades were the first mold we made. The elite blades from that mold come out about 230 grams. The Molokai blades are much bigger, but they come out at 250 grams--20 grams heavier. Wikis come out at 175 grams--55 grams lighter.

The jump in area is about equal between blades: 84, 95, 105  -- About 10 square inches. The weight change is 175, 230, 250  which is 55 grams and 20 grams difference. I think most of the difference in feel between the Wiki and the Maliko is swing weight. It takes no effort to recover a Wiki. It's spooky fast. I think that translates into a lower power feel. When we measure the deceleration for the Wiki blade vs Maliko it's about a ten percent difference, same jump as Maliko to Molokai. That's not a precise measurement since we don't currently have a way to directly measure the force applied to the shaft. But I try to pull them all about the same and we average a lot of strokes to get the decel number.

You really can't cut a Ke Nalu blade. Our blades are made differently, you'll get into the foam a lot more quickly than in a blade where the molds just come together with a wide margin. Our blades are shaped all the way to the edge--one reason they flow so differently. Look at the blade under  strong light compared to any other paddle--no margin, no flat area along the edges.  You'll also change the characteristics of the catch very quickly since you'll be taking off part of the flow-reversing curve. Certainly don't cut the upper third of the blade at all--it's wrapped, not pressed together.

We're still working on a winged blade, and the first blade to get wings will be a Wiki or smaller. The catch is absolutely crazy, it will be a Wiki that strokes like a Maliko. If we can just get it to stop darting around like a fishing lure it will probably be what you're looking for.
« Last Edit: March 26, 2012, 11:32:11 AM 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.

Waves4supper

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Re: review of the Ke Nalu (Pono Bill) paddle
« Reply #451 on: March 26, 2012, 12:16:42 PM »
That's not a precise measurement since we don't currently have a way to directly measure the force applied to the shaft. But I try to pull them all about the same and we average a lot of strokes to get the decel number.
 

Hi Bill, why not set up a 'lab test" to measure the force on the blade?

Here's how that could be done:
The paddle is in vertical position, fixed at the top (with a hinge, so no bending moment can be transferred at the top).
Place a dynamometer (or fishing scale or whatever) horizontally at the place where your lower hand would normally be.
Submerge the blade in a river or any other kind of water, which flows at about the hull speed of a typical 12'6" or 14" foot board.

With the equilibrium of moments around the hinge, and given the force applied at the lower hand position to keep the paddle vertical, it's a piece of cake to calculate the force applied on the blade.

You can play with the angles of the paddle and do some integration to calculate the total propulsive energy transferred during an entire stroke.
Add an accelerometer (read smartphone) to the paddle and you should be able to quantify the amount of flutter for various blades.

I know that finding a river flowing at exactly the right speed may be challenging. Alternatively you can use a boat in still water and hang the paddle far enough over the bow to eliminate any effects of the boat. A catamaran or an outrigger canoe could be an good platform as well.
Another option is to find a pool with a counter-current swimming system, and find a place where the current is regular enough and at the right speed.

Maybe this could be an idea for a comparative test for that australian sup-mag that did such an excellent comparison of the 14-foot boards.

PonoBill

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Re: review of the Ke Nalu (Pono Bill) paddle
« Reply #452 on: March 26, 2012, 12:25:02 PM »
Actually I plan to build a Water Tunnel this summer and that's exactly what it will be for--that and seeing flow dynamics a little better. Pretty simple to make, especially if I don't try to make it continuous--an elevated tank, a flow straightening section, then the test area with glass walls, a catch tank and a recirc pump. I've been sketching and sizing it for a couple of months.

I do have a paddle test spot in the Hood River that works as you describe, and I made a test tank with a watering trough and a big recirc pipe where I can stroke a paddle with a bungee cord, but they were both pretty unhandy and hard to get repeated data from. So far the best data comes from being on a board and using the Paddle Pod, but I want something more manageable.

My Paddle Pod contraption has a two axis accelerometer as part of the sensor array, and I'm going to add a gyro for angle. All the stuff people build for radio controlled autopilots and RC Helicopter stabilization has made doing this stuff much easier.
« Last Edit: March 26, 2012, 12:28:07 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.

Waves4supper

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Re: review of the Ke Nalu (Pono Bill) paddle
« Reply #453 on: March 26, 2012, 01:14:42 PM »
Excellent idea, Bill!
Being able to view and film from up close is also extremely valuable.

Make sure you make it deep and wide enough, as there can be quite a big influence from the bottom and sidewalls if there's nowhere to go for the water. The water velocity around your blade edges would then be a lot higher than in real life, which can lead to wrong conclusions.

http://en.wikipedia.org/wiki/Squat_effect


stoneaxe

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Re: review of the Ke Nalu (Pono Bill) paddle
« Reply #454 on: March 26, 2012, 03:18:53 PM »
I bet Diane is going to love having that in the backyard.... ;D

How long are you going to need the flow to continue and at what velocity? You're going to need a considerable volume of water if you aren't making it continuous. The squat effect won't have as much influence on a paddle as it does a ship given the limited length but you will still want to have plenty of area around the blade to get as accurate as possible. The channel walls effect flow as well. What you're doing is somewhat analogous to a flow meter. You'll want a long upstream section for laminar flow and a shorter section downstream with a weir at the end to minimize influence. A 3' x 2' x 12' channel (guessing at the minimum size) gives you 72 cu/ft and 538 gals static just in the channel. If you want to keep that flowing for a minute at an average paddling speed of 3.5 mph...you'll need about a 4,000 gal tank minimum each end. Might be easier to convince Diane you need an endless pool in Hood River... ;D
« Last Edit: March 26, 2012, 04:18:32 PM by stoneaxe »
Bob

8-4 Vec, 9-0 SouthCounty, 9-8 Starboard, 10-4 Foote Triton, 10-6 C4, 12-6 Starboard, 14-0 Vec (babysitting the 18-0 Speedboard) Ke Nalu Molokai, Ke Nalu Maliko, Ke Nalu Wiki Ke Nalu Konihi

PonoBill

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Re: review of the Ke Nalu (Pono Bill) paddle
« Reply #455 on: March 26, 2012, 05:28:34 PM »
It will be in the warehouse, with my race cars and the big tools I don't use anymore.

I forgot that you are the pipe king.

I'm planning runs of a few seconds. I'll have a recirc pump that's medium sized, maybe 30-40 GPM and probably 100 gallon tanks. Open the shutter, record the data, close shutter, refill. I figured on a weir to give me level control, it will usually be completely full. And I can set the flow rate anywhere I want with the shutter.

I don't need to get anywhere neat 3.5 MPH, the speed of a paddle relative to a board is much slower than that (the board moves).
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.

TEX_SUP

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Re: review of the Ke Nalu (Pono Bill) paddle
« Reply #456 on: March 26, 2012, 07:36:34 PM »
You could probably just use a holding tank at a higher elevation.  Run the tunnel for a few minutes until all the water has flowed into a catch tank, then use a small pump to refill the upper tank.

stoneaxe

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Re: review of the Ke Nalu (Pono Bill) paddle
« Reply #457 on: March 26, 2012, 08:03:17 PM »
Hadn't thought of the relative speed, and short runs will make it a lot easier. I think you'll still want bigger tanks though. What do you think the relative speed is? You can probably shrink the channel a little without too much issue to give higher velocity. Make a slide gate to allow fuller flow and build the upstream tank short and fat so as it empties the lesser head won't effect flow so much.. You'll get a slug of turbulence when you first open the gate so that water won't be worth much in your data. A second or two to let it settle down and some vanes will make it more laminar. Better to make it a bit bigger than you think you'll need so you have some room for error and experiment.
« Last Edit: March 26, 2012, 08:08:04 PM by stoneaxe »
Bob

8-4 Vec, 9-0 SouthCounty, 9-8 Starboard, 10-4 Foote Triton, 10-6 C4, 12-6 Starboard, 14-0 Vec (babysitting the 18-0 Speedboard) Ke Nalu Molokai, Ke Nalu Maliko, Ke Nalu Wiki Ke Nalu Konihi

PonoBill

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Re: review of the Ke Nalu (Pono Bill) paddle
« Reply #458 on: March 26, 2012, 09:40:08 PM »
If slip is 10% (it's less) then relative speed is about .4 mph. I didn't think about the acceleration of the water close to the edges, good thing I talked to you guys first. I'm thinking of making the viewing area long enough to be able to put instrumented hull models in too. We'll see about that one. There's actually a company that sells water tunnels, the tanks they use look like from 50 gallon for smaller in-lab stuff to several hundred gallons. I think they use bigger pumps than I plan to use, the taks are mostly to quiet the water, but their tunnels start at five figures and my budget is three, maybe nudging four.
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.

TEX_SUP

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Re: review of the Ke Nalu (Pono Bill) paddle
« Reply #459 on: March 26, 2012, 09:57:27 PM »
Are you talking full scale hull models?  If you are going miniature, watch your Reynolds number.

viatormundi

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Re: review of the Ke Nalu (Pono Bill) paddle
« Reply #460 on: March 27, 2012, 07:58:50 AM »
OK PB, I'll bite.

I'm in the UK. How can I get one of your paddles, and how much will it cost either with or without this new Bongo arrangement?

We pay 20% sales tax on anything coming into the UK from the USA, and that 20% is calculated on the price of goods *plus* the carriage costs.

Henrik F - since you seem to be closest to me, how much did it end up costing you in total?

It's the ability to change the length that is clearly the USP for me.

PM me the name of your local dealer. I'm getting ready to do a push to get some UK dealers. Going to do the UK first since I can't ramp production very quickly. It will probably be the most reasonable way to get one.

Of course you can order direct. Click on the Bongo button on the site and it will tell you what the likely freight will be. The tough part is that it's going to be the same freight for one or five since these aren't heavy, just bulky.

The shipping box size is 69" X 4" X 10" and the weight is 4 pounds.

Hi PB,
I hope you will have a distributor in Spain soon. It looks like ordering one of your paddles using Bongo becomes quite expensive. For example, a shipment of Wiki (worth 375 USD) to Spain costs total of 656 USD with bongo. Which is about 495 Euros. On the other hand, a qb Kanaha Elite Race 8.3'' costs here around 360 Euros (about 475 USD).

We're working hard on it. We think we can reduce our distributor minimum quantity a bit to make it feasible to to ship direct to European countries instead of trying to have a central European distributor. . And since we don't ship finished goods (they must be assembled locally) the duties might be lower. It's priority one--getting distribution in all European countries. For some reason our paddles are like Jerry Lewis--even more popular outside the US. I can't believe how much email we get from Australia.

Hi,
I look forward to that because ordering a Kenalu paddle to Spain via bongo ends up too expensive. Is there a possibility that I can order the paddle directly from you? I would also be interested in a paddle size between Wiki and Maliko.

PonoBill

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Re: review of the Ke Nalu (Pono Bill) paddle
« Reply #461 on: March 27, 2012, 09:21:14 AM »
Hi Vator,
We're working on setting up a distributor in Spain. or at least setting up a few dealers. The easiest way to cut the shipping cost is to ship multiple paddles since our paddles are very light--we can ship five in the same box that holds one and it doesn't cost any more money since it's the volume of the box that determines the shipping cost for light items. Doubling the box (taping two together) increases the total shipping cost a little but cuts the individual cost down to about $15, so consolidation is the way to go.

If you know of a local dealer that can handle some volume please PM me, in the meantime, we're working away at it.
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.

Waves4supper

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Re: review of the Ke Nalu (Pono Bill) paddle
« Reply #462 on: March 27, 2012, 09:45:35 AM »
True, you need a lot lower speed than board speed.

I once made a counter-current swimming system for an outdoor pool (one of those round things with an inflatable collar). We ordered a 920 l/min pump from www.pacific-motor.com for not too much (pump was about 250 $ I think, with shipping again as much).
The system actually worked, but we lost interest in the business idea when I found out such systems already exist (even for those cheap kinds of swimming pools which stand on the ground).
Besides, swimming wasn't comfortable (too much turbulence) and you didn't have to swim too fast.
We found it on Alibaba.com, but be careful as I have once read that not all advertisers are legitimate businesses.

Beasho

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Re: review of the Ke Nalu (Pono Bill) paddle
« Reply #463 on: March 27, 2012, 02:16:36 PM »
If you can't measure it you can't fix it.  Everyone likes to talk about how light their paddles are.  Well here is proof.  This is a Molokai measuring 76".  

497 Grams: Not bad for the biggest blade.

PS: My Kialoa Methane is 2 inches shorter and weighs 545 grams.

keloke69

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Re: review of the Ke Nalu (Pono Bill) paddle
« Reply #464 on: March 27, 2012, 04:06:32 PM »
If you can't measure it you can't fix it.  Everyone likes to talk about how light their paddles are.  Well here is proof.  This is a Molokai measuring 76".  

497 Grams: Not bad for the biggest blade.

PS: My Kialoa Methane is 2 inches shorter and weighs 545 grams.

That is so beautiful I can't stand it anymore. I've tried to justify it so many different ways but I just can't anymore. I NEED to try one of these for myself I've just heard too much. And to think that I've already spent so much on crappy aluminium paddles makes me want to kick myself.

These things are like a work of art. So for a 240 lb sup beginner paddling mostly flat water what is the best Ke Nalu for my money?

 


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