Kocho's GP Thread

Kocho recently started a thread that interested me. It went something like “A shorter, wider GP is better because it slips less than a longer, narrower GP.” Today I took two GPs out with similar loom lengths but different blade widths / lengths. I don’t have a watt meter to measure effort so I could only make judgments by feel. What I felt was the narrower blade wanted to act squirrely and fluttery for the first 3 or 4 strokes. The wider blade didn’t. At speed, the paddles were about the same. The winner by a nose, in my book, is the shorter, wider blade.

By that reasoning we should all be
paddling euro blades. I prefer the longer narrower GP’s as they are easier on the joints and work well for my body type (shorter legs, longer torso). I also prefer my style of paddle for sculling and rolling work. Wider paddles create a wider inverted grip which limits the amount of blade angle available to the paddler. Were I going strictly from point A to B in calm conditions I might prefer the wider blade, in my typical range of paddling conditions I prefer the longer narrower GP. I really feel it is a personal preference and not a correct or incorrect choice. Bill

Greenland paddles are like shoes
Everyone has different needs and with the wide variety of shapes, sizes and weights in Greenland paddles there is no one paddle that is right for everyone. The many differences all have advantages and disadvantages for various conditions and personal preference. I enjoy using many different sizes, shapes and weights at various times. They all work a little bit different and can teach you something.

Were the surface areas close to same ?
Just wondering.

They Were Close

– Last Updated: Nov-06-11 12:52 PM EST –

If they were off, I'd say the wider blade has a hair more surface area. I'd like to do another comparison on a windy day. It was slick calm. What I'm comparing is my faster cadence 'small chainring' or 'upwind' paddles.

Hey, are you making carbon GPs yet? You know I'll buy one!

That’s why …
… I use a WW paddle when the first few strokes matter most -:wink:

"What I felt was the narrower blade wanted to act squirrely and fluttery for the first 3 or 4 strokes."

The shape of the GP blade can have a great deal to do with to what extent it will flutter and when. Some are much better than others as minor variations make a big difference just as in EPs.

My experience has been that at lower speeds a narrow GP blade is prone to flutter if you overpower it. This is most often evident when trying to accelerate quickly from a standstill. As speed increases, the flutter stops even if power remains the same or increases. My experience is you can paddle even a loaded touring boat at a good clip using a GP with a 2.7" blade, but you can’t accelerate well at low speed.

Heh heh … one of these days.
Currently my time is not enough.

The problem is…

– Last Updated: Nov-05-11 7:20 AM EST –

...that if you make the blade wider than you can comfortably grip, you lose much of the versatility of the paddle, since you can't slide and extend it readily. It seems to me that you end up with a paddle that won't offer the bite of a Euro or the versatility of a GP and it's not ideally suited to either technique. Essentially, it's the worst of both worlds.

blade size
I just made a larger bladed/shorter length GP to try with surfing. Trying to get a bit more grab at the beginning. I think it works. I also paddle with a thinner/longer one and it does not flutter. You just have to try different things to see what works for you.

At speed, a GP when used canted works as a lifting airfoil, over at least some of its surface. This is to say there is a lift vector generated, a portion of which points in the direction of travel and propels the boat. A wing paddle operates the same way, as the name implies.

When accelerating up to speed with a GP, the paddle can be used in similar airfoil mode, or in standard paddle style, i.e. drag mode. In drag mode, drawing the paddle directly backward creates large drag forces which propel the boat. This is how the majority of Euro-style paddles function.

If you don’t mind accelerating somewhat slowly, then a GP can be used to get up to speed in lift mode, and it will show all its usual benefits, being easy on the joints, quiet, etc.

If you’re in a hurry, drawing the paddle backwards too quickly will kill the lifting behavior via flow separation (essentially a stall). The paddle then transitions to drag mode, as lift is not being generated. In drag mode, a wider, shorter paddle is preferable as many above have noted - lots of area far from the fulcrum creates the most propulsion.

If you can remain in lift mode while accelerating, high-aspect-ratio wings are more efficient, i.e. longer, skinnier blades are favored - this is a classic result of airfoil theory.

Anytime you ‘overpower’ a GP, you are exiting lifting mode. The direct cause is high flow velocity relative to the moving blade. This is why an overpowered blade tends to flutter - the streamline pattern over the foil is disrupted, and the stagnation point is no longer fixed. Oscillation of the stagnation point on the foil causes the flutter. This is also why flutter is more common while accelerating, as that is when the magnitude of the relative velocity is greatest.

Blade type then is at least partly based on paddling style - impatient types will prefer a short wide blade, and zen types will prefer a skinny stick. But we could have figured that out just by reading the posts above… :wink:

The design of the greenland paddles
allows the use of the canted stroke which eliminates fluttering. To get the most out of a narrow blade it should not be used perpendicular to the water. Sculling and canting get the most out of it. Wider blades use less of a cant or can work well being used perpendicular to the water.

Not Really Wide
The shorter paddle is 3.5 inches wide and the longer paddle is 3 inches. Not a huge difference but apparently enough to affect flutter. For me, anyway.

Does Toksook have relevance 2011
Years ago Derek Hutchinson designed the Toksook


Does it still have relevance in modern kayak culture ?

People seem to go "“black/white” ie. greenland/euro

but few paddle a hybrid design.

gp size
My new surf one is 4.5" and my regular one is 3" wide. The wider one is about 78" long, the narrow one 84". My kayaks are 19.25" wide or so and they both work well. I did like the new one in the one day of good surf we had. They are easy and inexpensive to make, so why not make a few and see what works best for you.