Sunday, April 02, 2006

Paddles & Planes, Part III

Turner Wilson completing an under-the-deck sculling roll in Freya's breakapart kayak (he loooooved it):

Turner making tea for himself & Cheri:

OK, OK, one more to finish this up - I'd meant to do this & the last in one post but I was having fun surfing the net looking for info on the histories of the different kinds of paddles, got more into that than I planned too. I was going to leave it at that until tomorrow at least BUT I went and made it sound like some big cliffhanger, so now anybody who read it probably thinks that Turner let me in on some big magic secret of the Greenland stroke and I'm just holding out to be coy before revealing all. Thing is, "coy" is not part of the human-relations vocabulary I'm comfortable with, I'm a pretty straightforward person & not fond of beating around bushes. I can, however, get distracted into wandering around bushes & examing, oh, interesting stones & small striped lizards & things in a way that could be mistaken for bush-beating.

So I want to end the suspense because the longer I leave folks in suspense, the more annoying it's sure to be when I do & it turns out to not really be all that dramatic a secret!

In fact - the incredible, astonishing, amazing, eye-opening thing that Turner said to me during my first-ever lesson in the forward stroke was simply this:

"The push happens after the blade passes your hip".

We'd started out the afternoon as part of a larger group who were being taught control strokes by Greg Stamer. There were a few minor differences from the control strokes as done with a Euroblade, but differences that the nature of the way a Greenland paddle behaves in the water made feel quite natural. A review under competent eyes never ever hurts, but I was pleased to find that my own independent efforts were not too far off base. As the larger group (which had done their forward-stroke work in the morning while I and a couple other more experienced rollers had worked on our rolls by the beach) moved on to bracing, Turner took me & the other guy who were lined up for afternoon forward-stroke review off to get going on that.

We started out just cruising at a comfortable pace for a little while while Turner watched us. Turner's first pointer was "Cant the blade a little more". I knew just from reading here & there that with a Greenland paddle, you tilt the blade forward a bit for the catch (the moment the blade enters the water) - the paddle automatically dives, but the flotation of the wood counteracts the dive & brings it back up. I'd thought I was doing so, but I needed to exaggerate that more. Actually I should have known that after Sea Level posted a great writeup last fall of a "mini Greenland-fest" (strictly informal) that happened at the barge last fall - we'd both been talking about the interesting way our Greenland paddles seemed to gently vibrate in our hands while paddling, he came up with the description "sloosh, sloosh" - well, Greg Stamer was reading & explained that, uh, that's not supposed to happen, "sloosh sloosh" is the sound/feeling of cavitation (bubbles following the blade) and ideally that doesn't happen. So finding out that I still wasn't canting enough, even though I thought I was doing it, wasn't a surprise at all.

So that cleared up pretty quickly.

The next instruction was a little more push on the upper hand.

That's when he hit me with the instruction that I think actually may have stopped me dead in mid-stroke.

Turner: "The push happens after the paddle passes your hip".

Me:(hearing sounds of screeching brakes & rending metal in my head)"After the paddle WHAT?"

Now I haven't had the chance to really practice the Greenland forward stroke since then, since practicing a new technique is something I prefer to do solo and the conditions on the weekends I've been paddling have been such that I've preferred the safety of "the usual suspects" (as I tend to think of the group of friends with whom I do most of my winter paddling) - but I have a feeling that that seemingly innocuous phrase may have been the key to the detail I figured I must have been missing!

This is also where that whole exigesis with the different planes comes back in, too.

You see, the first fine point of the Euroblade forward stroke that Richard Chen See worked on with me, during my first year at MKC, was that the blade needs to come out at your hip. This is one of those things that I talk about getting from classes - those seemingly minor details that make a major difference, and completely counterintuitive. A stroke that's 12 inches long is going to be more effective than one that's 5 inches long, which is going to be more effective than one that's 2 inches long, so you'd think that the longer the stroke, the better, right? Well, with a Euroblade, you'd be wrong! The fact is that once the blade passes the hip, the angle gets to the point where a lot of drag is being created. I don't know if this is exactly how it works but I tend to be a very very visual thinker, and the picture I have of what happens when the blade passes the hip is that at that point, the blade is actually beginning to angle up towards the surface, and the further that goes, the more your effort is being wasted on shoveling all the water that's on top of that big flat scoop up towards the surface. And water is HEAVY! To maximize the efficiency of a forward stroke with the Euroblade, then, you bring it back only so far, then let it slice out sideways (the same is true of a wing, probably even moreso, only the wing, used correctly, pretty much slices out of it's own volition, you just do the stroke right & don't interfere).

That was a hard thing to learn. Even though I believed what Richard was telling me, it felt absolutely bizarre to get used to keeping the entire stroke in the forward quadrant of the boat. Once I'd trained myself to do that, though, and added it to the nice effective torso rotation that Richard had managed to get me doing before he even started on this, I found myself doing a lot better. With those two pieces in place, it got to the point where once or twice Eric, with whom I was still on good terms at the time, sent me after husky men with high opinions of their abilities...generally they'd get the point that there was something more than muscle involved & be a lot more amenable to listening to pointers after the wimpy-looking chick (I've built up my upper-body strength since then but that first year my arms & shoulders were pretty no-account) cruised past 'em without even breathing hard. Heh heh heh.

Apparently, though, with the design of the Greenland blade being so different that the Euroblade, the blade can and should travel past the hip. I, however, have so thoroughly trained myself NOT to let a blade pass my hip that the concept of even trying such a thing would never have crossed my mind.

I tried it, though, and the boat did seem to be moving through the water with more alacrity. I do need to practice it some but I think the thing I may have been missing all along was nothing less that THE ENTIRE BACK HALF OF THE STROKE!!!

In the immortal words of Homer Simpson - D'OH!

It was a couple of years ago that Nigel Foster first truly made me really start looking at the "why's" of the ways different boats behave in the water (he put me in one of his Silhouette boats & started running me through the basics - I think it was the low-brace turn where I was just about ready to cry 'cause everything that I could do quite confidently in my banana-esque spins-on-a-dime Romany was failing completely in front of this very topnotch instructor - thank God, though, he then explained EXACTLY why I was doing so miserably - that lesson in the basic differences (and the hows & whys thereof) of a long-keeled Silhouette and a rockered-like-a-whitewater-boat Romany was probably the part of that private lesson that was the biggest eye-opener & has stayed with me the longest (AND had me signing up for two full days with Nigel at Sweetwater, too - more of that, please!).

What the water is doing under two different hull shapes, I'm getting better, I think, at picturing. I think I also have a pretty good picture of how the forward stroke works with a Euroblade, and why the forward stroke with a Euroblade is so much of a "front-wheel drive" affair.

Can't quite picture what's going on with the GP yet. Learning this stuff seems to have two stages - first, I just do something 'cause somebody who knows what they're doing tells me too, then gradually I start being able to imagine a picture of what's going on. While still operating within the same basic principals (hello, Bernoulli!) as the Euro, clearly something very very different is going on, 'cause the drag that you get if you use a Euro incorrectly is not a problem with the Greenland.

I was hesitating to draw parallels too direct to my planes, but I can't help but look at those long, thin wings of the Global Flyer - wings designed specifically designed to maximize lift and minimize drag - and see a design that looks an awful lot like a Greenland paddle.

Makes me wish I had access to one of those tanks where they test hydrodynamics of things - how cool would it be to do a comparison between the flow of water & the forces generated by those 3 different kinds of paddles?

As it is, what I do have is a dock and a river...if you're in the Chelsea area anytime in the future and you see somebody who's apparently gone completely insane & is trying to paddle a dock moored to a solidly secured barge, please don't call the loony bin, it's just me experimenting with all my different paddles - the fighter plane/jumbo jet pilot trying to learn some Global Flyer secrets, as 'twere. Not going to make any serious claims to sanity (after this series, how can I?), but I can at least promise that I'm at least harmless to myself and others.

BTW if anybody knows of such a thing having been done I'd love to hear about it.

In the meantime I think I will go spend a little more time in this very nifty physics of sailing site. Got some neat little virtual-lab things that might help my visual images of all things Bernoulli-effect-related. That site, btw, was recommended by Adrift at Sea on Tillerman - the Tillerman (and his incredibly well-informed commenters) have been geeking out (NO disrespect meant by that, Tillerman, sir! Quite the opposite in fact!) on the physics-of-sails topic at the same time as I've been doing the same on different paddles...I could just go on all night (in fact I am not even to go into the different handling characteristics of the 3 different Greenland paddles used in the session - Turner has a big solid one, I was using the lighter of my 2, and the other gentleman in the class had a carbon fiber one - we all ended up switching out & the differences were really pronounced).

Past my bedtime, but worth it - now if I really do disappear into a blogging black hole next week while the March books are closed & the budget finalized, at least I haven't left you all hanging. Didn't want to do that!