An obituary of Allen Rosenberg, Olympic Rowing Coach appears in todays NY Times (http://www.nytimes.com/2013/12/14/sports/olympics/allen-rosenberg-olympic-rowing-coach-who-transformed-the-sport-dies-at-82.html?_r=0)
Here is a quote that I think is quite relevant to kayak paddle stroke technique:
“He took what was often a frenetic and power-washing way — putting the oar in the water and whaling away at it — to something more relaxed. His constant comments were about lightness of hands and relaxing and balancing in the recovery part of the stroke. Concentrate on a long pull in the water, quiet and even. The less water you disturb, the faster the boat goes.”
Probably the long pull part does not apply to a wing paddle. On the other hand, the GP is perfect for the long, even and quiet stroke.
When I was sculling in Philadelphia in
'65, Al Rosenberg watched me from a distance, and when I got to the dock, he called me over and in maybe two minutes of quiet talk, gave me more and better coaching than I had ever had previously as an oarsman. And I wasn’t one of his ‘64 crew that had stomped opponents at the Japan Olympics. I was just a guy taking up locker space at Vesper Boat Club.
Al was one of those coaches who had good eyes, who could spot differences in technique and quickly think of ways to bring about improvement. A lot of coaches thought they could do that, but if their crews improved, it was mostly through long trial and error.
Regarding the quote, Vesper’s stroke didn’t look that long and smooth. All modern racing strokes are short. What Al did want’ was for his oarsmen to relax during recovery, to drop that blade in without for-splash or back-splash, and to get power on right now with the arms taking up slack and the legs driving. I don’t see much in common with GP technique, except that a clean entry without premature force is essential. Learning to do that in solo canoeing has allowed me to eliminate the J-stroke correction.
gp commonality
The commonality with the gp seems to me that it can be made to disturb the water hardly at all. And that it is very easy to see and hear when the technique is slightly off and one is disturbing the water. The main point of the quote that struck me was the efficiency benefit, with any paddle, of no splash, either on entry or exit, and even no ventilation during the stroke. Easier to achieve and observe with a gp, I think.
I think you should watch some top-notch
rowing crews, and see if Rosenberg or any other coach expects “undisturbed” water. The times statement about long strokes is incorrect, also. In the 60s, strokes were shortened, and stroke rates were increased, by all crews, and it hasn’t changed since.
These guys are going nearly all out for 2000 meters, with long strokes and undisturbed water?
I’ll tell you what Rosenberg wanted. He wanted that oar blade dropped neatly into the water, without backsplash toward the bow, and without fore-splash ripping water off the surface toward the stern. An instant after the blade dropped in the water, the arms would tighten, not bend, just enough to lock the power face against the water, and then the legs would drive, hard. A deep swirl would form around each blade, and when the blade was feathered, all those deep swirls would be left behind. When you view a race from a blimp, you will see a pattern of eight deep swirls left behind each shell, while the rowers are forming eight new deep swirls.
That’s what you want. As clean an entry as possible, hard leg drive, back backing a little, arms pulling in the latter half of the stroke, blades out. Simultaneous, no scraping or sloshing the water surface.
I try for essentially the same thing whether I’m kayaking with a Euro blade, of canoeing. I don’t know how I would manage a GP paddle, but I surely would try for a clean catch and avoid scraping water off the surface.
The comments of some of the oarsmen in that article can be taken literally only if compared to contemporaneous bad crews. If placed against the entire almost two centuries of competitive rowing, they make no sense at all. Rowing style in the 19th century started long and smooth. It mostly continued that way until the 1930s, when sculler Joe Burke, rower and boat builder Pockock, and the Washington crew shortened the stroke. When Washington won (including the 1936 Olympics) they were notably smooth, but with a short, hard stroke. They were known for coming from way behind to win their races. There’s a book about it now, “The Boys in the Boat.”
I agree
The water is definitely disturbed, and disturbed more greatly in proportion to the propulsion that's generated. Regarding those "deep swirls", as a more-casual rower of fixed-seat boats, I've long been observing those little pockets of turbulence behind the boat and find them to be quite handy as a visual reference (since their location in the water is nearly stationary) for how fast the boat is moving. Looking at featureless water doesn't give much of an impression of one's speed (in my experience, canoeing on gently rippling water in low-light conditions is an extreme example of that, even so much so that an illusion sometimes is created that makes it seem the boat isn't even going directly forward), but such an obvious "landmark" as the swirls left by oar blades certainly does.
As to GP blades being naturally more silent on entry and exit, I have to wonder, "compared to what"? I have come to expect any decent paddle or oar to be completely silent on entry and exit if used properly (not so sure about how "perfect" this silence can be at racing speeds, but surely it's the goal to aim for). Certainly I think that ventilation simply shouldn't happen at all so stating that the GP doesn't ventilate doesn't strike me as being anything special.
Finally, as to the GP being more suited to long strokes, I have to question whether that's actually correct. A long blade, when it travels a long arc so that its angle changes a lot during the stroke, is fighting itself in the water because the difference in distance traveled relative to the boat is much greater for the tip of the blade than the base. From the water's perspective, if the center of the blade is stationary, the tip will be slipping backward (contributing to propulsion) and the base will be forced to move forward (and the resulting drag reduces overall propulsive power). You can't make all parts of a long blade go the same speed, whether in reference to the boat or water. The longer the stroke (and therefore the greater the change in orientation of the blade during the stroke) the greater the difference in distance traveled will be between the tip of the blade and the base. I see this on the oars of my rowboats, in that with the blades fully submerged, part of the shaft is submerged too, and the submerged part of the shaft actually "drags forward" through the water in response to the changing angle of the shaft during the stroke (the submerged part of the shaft "follows" the boat, albeit at slower speed). That same thing is happening to the blade to some extent - the part of the blade that is closest to the boat is moving forward through the water in response to the change in angle, though not nearly as much as what I can observe for the part of the shaft that passes through the water's surface, a foot or so farther inboard than the blade - and naturally this gets worse with longer strokes. I mentioned in one other discussion of such things that the elimination of this problem was surely the goal behind designing the much shorter, hatchet-style blades used in modern competitive rowing.
I'm not knocking the GP at all, and I recognize that the fact that there is a pronounced differential velocity between the tip and base of the blade need not be considered a serious flaw in the context of normal use, but that situation certainly becomes more severe with longer strokes. For what it's worth, don't GP users usually take pretty short strokes, with minimal motion of the upper body? I've always noticed that that seemed to be the case.
Oh, I just thought of something else that I'm surprised I didn't think of before. News writers are notorious for making amazing mistakes when writing about things they do not understand. I wonder how much of what was written, since it is obviously wrong, was simply a case of the reporter not understanding the topic and writing it up as he pictured the meaning to be in his own mind.
Many GP paddlers
develop a forward stroke similar to the stroke used by wing paddle users. There is actually quite a bit of rotation and/or a crunch type deal going on with some of the good GP paddlers.
Tweaks
Just a couple of remarks further to GBG’s post.
Technically speaking, the swirls left behind when the paddle is removed are the physical manifestation of the vortex created by the interaction of the paddle with the water. GBG is correct that the more intense and compact the vortices created, the greater the propulsion.
The vortices are not generally turbulent, although some time after being created they may suffer what’s called ‘vortex breakdown’ and become turbulent. This breakdown leads to faster dissipation of the vortex. The dimple in the surface is caused by low pressure in the rapidly spinning vortex core, which you can demonstrate for yourself by stirring your coffee quickly or pulling a stick briskly through the water.
In fact, a paddle create a single horseshoe-shaped vortex, which begins and ends at the water surface, looping down around the end of where the paddle was. That’s why there are generally a pair of dimples created by each paddle.
Re the GP, I’ll say from close observation that when using it, no part of the blade is moving forward relative to the water, and I tend to take long leisurely strokes. The geometry of the stroke is such that it just doesn’t seem to occur, even with a vertical stroke. I think it has to do with the fact that there really is no fixed pivot point (as with oars). When the paddler is rotating the body while paddling, I think the effective center of paddle rotation might actually quite far away, but it’s pretty hard to visualize exactly what’s happening. Certainly there will be much variation between different paddlers.
Also, further to what g2d states above, when sprinting or getting up to speed quickly with a GP (or any paddle) it’s normal to take quick, fast strokes. This generates energetic vortices, creating tight, rapidly swirling vortex pairs on the surface, indicating high propulsion. Birds and fish exhibit the same behavior when sprinting, it’s a normal consequence of the vortex dynamics of propulsion.
Tweaks #2
I appreciate hearing your thoughts on what I'd written earlier. At one point I had considered modifying what I wrote, but wasn't going to bother until I saw your reply. Thanks for correcting my wrong use of the word "turbulence" too (I would have called any kind of swirl turbulence).
It occurred to me last night that I'm not sure the inboard part of an oar blade is actually moving forward, even though the more-inboard part of the shaft certainly is, at least with my boat that has the longer oars. With the other boat, where the oars are just a foot shorter, I don't think the shaft slices forward in the water very much, which makes me think that with both boats, the inboard part of the blade is probably almost stationary, so that the outboard ends slip backwards.
Along those lines, it occurred to me that GP blades could be doing something similar, with the tips slipping quite a bit due to the changing orientation of the blade, with the closer part of the blade slipping very little or not at all. You are right that the pivoting action of the shaft is completely different, and I'm guessing that most of the "working portion" of the shaft is moving backward relative to the boat as the angle changes during the power stroke, so there'd be much less tendency of any part of the submerged part of the shaft or blade to "follow" the boat.
I'm still not sure long strokes can be more efficient in the strictest sence, but regarding what you say about long strokes with the GP, I do a similar thing when rowing. When rowing I'm quite certain that short strokes are more efficient in terms of making use of power applied during the stroke itself, but I think that's less efficient overall, considering all the other types of motion going on which are not "at that moment" supplying propulsive power. To clarify, I'm quite certain that short fast strokes when rowing are more efficient in terms of use of the blades (certainly in part this is because it keeps the blade motion and alignment more closely in-line with the direction of travel), but that method requires my body to move more rapidly on the recovery stroke, as well as overall in a way that is much more difficult to sustain, especially when going at a comfortable cruising speed (not sprinting). I definitely feel more efficient in terms of all types of required motion when I use longer strokes instead of short choppy ones. So even if the blades themselves might be being used in a less-than-optimal way, the greater efficiency of the other parts of the stroke makes up for that, in terms of being able to keep going comfortably for long distances.
Agreed
I agree about long vs. short strokes. I think short, fast strokes are significantly less efficient, but are much more powerful, i.e. impart more energy per unit time, and require a lot of energy input.
Long easy strokes are less powerful, but more efficient, i.e. they provide less energy but are also less wasteful of the energy input.
To go fast, one must accept the penalties of low efficiency. That's why the techniques of sprinters must be fundamentally different from long-distance athletes of any type.
Also, any motion created by the paddle that does not contribute to the vortex is wasted. Any wakes, ripples, splashes, etc are wasted energy. Also, if the vortex created by the paddle is turbulent (e.g. a high-speed vortex created by vigorous paddling), that turbulence energy superimposed on top of the vortex motion is wasted as it is random in direction and does not contribute to forward motion.
efficiency
g2d said: 'I’ll tell you what Rosenberg wanted. He wanted that oar blade dropped neatly into the water, without backsplash toward the bow, and without fore-splash ripping water off the surface toward the stern." ……“no scraping or sloshing the water surface.”
That is how I interpreted the ‘no disturbance’ advice. I did not think Rosenberg was at all referring to swirling water once the blade is fully immersed and generating force.
cardelo said: “Long easy strokes are less powerful, but more efficient, i.e. they provide less energy but are also less wasteful of the energy input. To go fast, one must accept the penalties of low efficiency.”
Energy is lost (inefficiency) in three places: Drag of the boat. Interaction of paddle blade and water. And, most importantly, human body ergonomics.
Drag must simply be overcome. The efficiency of a wing comes mainly from enabling efficient body ergonomics. The short stroke with strong leg action and unwinding of the core is key. The stroke is short because the body is fully unwound. With the wing stroke technique, a long stroke is a contradiction in terms because it would no longer be a wing stroke. The lift of the wing and the resulting outward motion in the direction of its leading edge promotes efficiency, whether racing or not.
While one can use a GP similarly to a wing, that does not result in a true wing stroke. The longer GP blade requires some time to get fully immersed, so one cannot unwind early in the stroke, as with the wing.
It is not that the GP enters more cleanly than other paddles, but that it is easier to see any water disturbance or ventilation and correct for it.
A longer stroke with a wing would be less efficient than a shorter stroke. But a longer stroke with a GP may or may not be, I am not sure. The GP can be used high or low angle.
I think that for pacing over 20 miles,
a GP paddle should be excellent. For racing over 2 miles, a short blade and high angle are very good, though not as good as a wing paddle.
For rowing 20 miles, a longer stroke may well be better. Guideboatguy has even suggested that sliding seats may not be an advantage for long distance. For racing 2 miles, a shorter, harder stroke has been proven more effective.
I’m sure we still have a lot to learn about GP, Euro, and wing paddles.
Clarifying the sliding seat issue
I would say the sliding seat has no real advantage for small, easy-to-move boats as long as you are not sprinting. Clearly a sliding seat would provide a huge advantage for a large, cumbersome boat, such as the ones used by those people who do solo ocean crossings, and it goes without saying that they are best for racing.
Here’s an analogy. If you were to reach down to pick up a basketball, consider what would your reaction would be if a bystander said “you know, you really should squat down and lift that thing using your legs, because your legs are a lot stronger than your arms and back”. That’s the situation when rowing a small boat at easy cruising speed all day, because arms and back aren’t being taxed much at all. Now, if you were lifting a window-style air conditioner, the advice about lifting with your legs would be appropriate, just as using your legs for rowing would be best for moving big heavy boats, or smaller boats at a racing pace.
catch with GP versus wing
Interesting post, but I don’t entirely agree on a few of you points:
“While one can use a GP similarly to a wing, that does not result in a true wing stroke. The longer GP blade requires some time to get fully immersed, so one cannot unwind early in the stroke, as with the wing.
It is not that the GP enters more cleanly than other paddles, but that it is easier to see any water disturbance or ventilation and correct for it.”
A GP has long blades, and you have to fully bury them. I agree that the long blades do require a split second more time to bury, but this doesn’t mean you can’t “unwind early”. Just like a wing, you can first wind your torso, bury the blades completely, and THEN unwind your torso. I don’t find this to be a significant difference between a wing and a GP. Most kayakers could benefit from a “micro-pause” after their catch anyway, as many kayakers apply power before they have fully immersed the blade (creating turbulence and ventilation).
Regarding entering the water more cleanly, just as a sword enters the water more cleanly than a shovel (said slightly tongue-in-cheek), so does a narrow, completely symmetrical sharp-edged GP as compared to a highly asymmetrical, strongly cupped wing blade. The cup on many wings requires a very precise catch, stabbing the tip into the water to enter cleanly (spear the salmon), whereas with a GP, I can stab the tip of the blade or slice the blade in along the bottom edge, without so much as whisper of noise or splash (in flat conditions). I have been working on my wing stroke for years and still cannot come close to the clean, quiet entry of the GP. They are amazingly quiet.
That said, I’m a few minutes faster per mile in a short race with a wing, and prefer a wing for short races for that reason, but as the miles accumulate I’m faster with a GP and they are less taxing on my body. YMMV.
Greg Stamer
wing vs gp catch
It seems to me that with the wing one applies immediate and large power just at the instant of the start of the unwind, vs more gradually with the GP. The wing just grabs the water instantaneously, ready for max power application. The difference seems significant to me, but I am not a racer.
Your point about no whisper or splash is the point made by Allen Rosenberg about not disturbing the water, and applies, I think, to any paddle. I agree that it is easier said than done with a wing, and much easier with the GP.
I was very interested in your experience that you can go faster over a long distance with the GP than the wing. But did you not use your wing rather than a GP in the long distance race in the Epic 18 that you recently reported on?
gp and wing opinions and ramblings…
I agree that a GP builds power more slowly than a wing. That said, the stroke with a GP is slightly longer due to the long blades. Even if you exit when your pulling hand reaches your hip, the blades will exit behind you. A common technique is lifting up on the canted blade on exit for a “boost”.
The slower building of power is is both an advantage and disadvantage. The advantage for long distance is that your body doesn’t suffer as much initial shock as with the “full-on” power of a large blade.
The fastest paddle depends on the situation, of course. 500 meter sprint, 10mile race, 300+ mile endurance challenge. I would use a different paddle type for each.
At some point in the long endurance races the winner is the one who simply keeps the kayak moving (often at a fairly modest pace) and who sleeps the least. Apart from efficiency, good technique creates less postural issues and pain, so is rewarded, even if high speed is not a factor. Greenland technique, with a lower hand height and close hand position is very strong and gentle to your body (especially for long distances) as compared to techniques where you hold the paddle high, with a wide grip and with nearly extended arms. I’m not saying that you can’t use a wing for extended events, but I do believe that you need to spend more time doing weight training and conditioning to handle the additional stress. In my case I needed to work on my deltoids.
To finally get to your question, in my last long-distance race I used a very small-bladed wing (ONNO Small Endurance Race Wing). I used a wing for fun and variety and to test my wing technique, and simply because none of my current GPs fit the kayak.
A “regular” GP might not give you the proper reach if you are not in a narrow, low-volume Greenland kayak. I determined through trials that I need at least a 25-26" loom for a GP to have adequate null clearance in an 18x (my normal GP loom for touring is 22-24"). The typical “go-fast” kayaks are wider and have more volume than a typical low volume “Greenland-style” kayak, especially when relatively unladen, and in my case I’m also sitting on a seat pad which makes the mismatch even more acute. I used an Explorer with a GP around Iceland but it was so heavily loaded (down to the black seam) that it sat low in the water and reach was not an issue.
Last year I was working on a custom GP with BlackLight for a 90" long paddle with a 26" loom, but unfortunately that project fell through due to a change in ownership of the company. The paddles are being produced again, so It’s possible that this is an option for next year. The Blacklight is a good choice for speed due to it’s extremely sharp edges and tips, and its light weight.
Greg Stamer
few more comments
"… the stroke with a GP is slightly longer due to the long blades."…
It seems to me that the greater length of the gp is due more to the stroke difference than the length. The wing blade is placed nearly vertically so that its leading edge moves mostly outward during the rotation. It can’t move that far outward, which requires a shorter stroke.
“Greenland technique, with a lower hand height and close hand position is very strong and gentle to your body (especially for long distances) as compared to techniques where you hold the paddle high, with a wide grip and with nearly extended arms.”
Seems to me you conflate lower hand height and close hand position, which are independent. There is no reason close hand position is “very strong”. Certainly not stronger than wider position.
“To finally get to your question, in my last long-distance race I used a very small-bladed wing (ONNO Small Endurance Race Wing). I used a wing for fun and variety and to test my wing technique, and simply because none of my current GPs fit the kayak.
Nothing like fun and variety. Lately I have been switching between my GP, wing, and conventional Euro during a typical day’s outing, going back to the beach to change paddles and stretch. It makes me appreciated each by comparison. Sometimes I start with the GP and sometimes the others.
“A “regular” GP might not give you the proper reach if you are not in a narrow, low-volume Greenland kayak. I determined through trials that I need at least a 25-26” loom for a GP to have adequate null clearance in an 18x (my normal GP loom for touring is 22-24”). "
I have a Q700, similar in size to your 18x and use 24" loom on my GP. But this has nothing to do with reach. I don’t see that going from a 20" beam boat to a 21 or 22" boat should have an impact on loom length, though I have not tried any 20" low volume Greenland boat.
“Last year I was working on a custom GP with BlackLight for a 90” long paddle with a 26" loom,…"
Wow, that seems a very wide loom. Have you actually tried anything similar?
more opinions, long
"It seems to me that the greater length of the gp is due more to the stroke difference than the length. The wing blade is placed nearly vertically so that its leading edge moves mostly outward during the rotation. It can’t move that far outward, which requires a shorter stroke".
Many contemporary coaches now teach for the wing to move straight back for the first third of the stroke, and then to flare out. From above the path looks like a “J” rather than an inverted “V”. This is the method currently taught by Chalupsky, Mocke and some others. My wing stroke had much more of a diagonal flare (inverted “V”) and Chalupsky quickly corrected that in coaching that I had with him this year. That said, this is by no means universal and opinions vary.
With a GP, even if you take the paddle out when your pulling hand reaches your hip, the long blades still come out well behind you. There are techniques used to exploit that, by lifting the blade out of the water at the exit, while retaining the forward cant (tilt) of the blade to generate additional lift (at the expense of some extra effort).
“Seems to me you conflate lower hand height and close hand position, which are independent. There is no reason close hand position is “very strong”. Certainly not stronger than wider position.”
Hand position on the loom affects how high you have to lift your arms to achieve a vertical blade at the catch. A wide grip requires a lot of arm lift to achieve a vertical plant, a narrow grip requires much less lift for a vertical plant. This is a bit confusing, I have a blog post at http://www.gregstamer.com/2012/02/12/greenland-paddle-wing-paddle.
When lifting a load and exerting force your shoulders are most protected from injury (bio-mechanically strong) when you keep the load close to your torso, elbows close to your torso without employing a wide grip. A “Frankenstein” position (although with a slight bend in your elbows), extended arms, wide grip is still commonly taught for racing. It does produce great amounts of power, but it stresses your shoulders and body.
Generally you find that K1 sprinters use a very high stroke and wide grip (pushing hand around eye level or above). Surf ski paddlers often race for longer distances and often hold the paddle lower. GP paddlers are at the end of the spectrum with the narrowest grip. The narrow grip and technique reduces the amount of lifting that you have to do per stroke. While not as good for an explosive sprint this technique reduces wear and tear over the long haul. However, there are no hard-and-fast rules, and personal variation rules.
Interestingly, Chalupsky is now coaching to keep your elbows more bent to keep the force closer to your core. That said, he is still not a fan of narrow grip width (such as used on a GP). This may be a hold-over from the days of arm-paddling when you used a wide grip so that you never crossed the center-line on a stroke. If you are truly using torso rotation, rather than arm-paddling, you don’t need to use the “put the paddle on your head and make a right angle bend in each arm” sizing method. That is very old school, IMO.
In a lesson with Lee McGregor, he advised that you should hold the paddle with about the same grip as you would do for a push-up. That makes more sense to me, and is a narrower grip than what is commonly taught. Lee also advises to use the smallest blade possible, that will do the job, which I also agree with.
“I have a Q700, similar in size to your 18x and use 24” loom on my GP. But this has nothing to do with reach. I don’t see that going from a 20" beam boat to a 21 or 22" boat should have an impact on loom length, though I have not tried any 20" low volume Greenland boat"
“Wow, that seems a very wide loom. Have you actually tried anything similar?”
Maligiaq Padilla uses a 24" loom, even for a very low-volume Greenland kayak where your hands are nearly in the water, when sitting upright. A Greenland paddle is matched to the kayak. The standard sizing for Greenland paddles (e.g. one arm-span plus a cubit and a shoulder-width loom) assumes that your kayak is only slightly wider than your hips with a very low foredeck.
As your kayak gets much “bigger” than a regular SOF Greenland kayak the paddle needs to change (longer loom, perhaps a longer overall length) so that you can fully bury the blades. Ideally your pinkies should be almost in the water when you bury the blades.
At the Greenland championships competitors usually use different kayaks and paddles for the races, versus the rolling events. The “racing” paddles are often very sharp-edged with longer looms (24" range).
Best,
Greg
Actually,
The trick is to “lock” and move the blade forward. The canoe or kayak moves in the direction of the force.
wing j, etc.
Never heard of the wing j stroke, and I am skeptical. The wing blade does not want to go straight back, as far as I can tell. Do you have a video link to someone doing it?
I take your point that a close grip on a gp would allow a more vertical stroke with a gp. But I don’t see why a close grip vertical stroke is particularly desireable with a gp. I tried it and it does not feel good.
I also don’t see why a wider grip with a gp would stress the shoulders.
The one arm plus a cubit means of setting length seems foolish to me. There is no substitute for trying different dimensions to see which works best one’s particular body, stroke style and boat.
Chalupsky’s point about bent arms keeping the forces closer to the core seems a very interesting insight to me, and I will play with it in my next few outings.
For an efficient forward stroke, whether gp or whatever, a slightly wider grip just seems better to me, whether racing or not. Around 24" loom, as the racers that you describe use, is about right. Maybe not for rolling, I don’t know.
flattened J and more…
"Never heard of the wing j stroke, and I am skeptical. The wing blade does not want to go straight back, as far as I can tell".
The book, "Surfski with the Pros" by Kevin Brunette (features Dawid and Nikki Mocke), has a section that describes the paddle path. The following is from the text; "Pull your blade in a shallow arc in a slightly outward direction, while rotating and twisting your upper body. The path of your paddle should resemble that of a flattened-out 'J', identical on each side of the ski". This agrees with what Oscar is teaching. In each case the blade is "allowed" to flare laterally but the primary direction of movement is aft. I discussed this with Oscar and he corrects a lot of wing blade students who have the idea that the relative blade path should almost be at right angles to the keel, rather than "moving backward" at all. My stroke was more of an inverted V, but he suggested that I change the path to more of the flattened 'J'. Again, as I said before, there are a lot of differing opinions on this.
"I take your point that a close grip on a gp would allow a more vertical stroke with a gp. But I don't see why a close grip vertical stroke is particularly desireable with a gp. I tried it and it does not feel good".
There is a common misconception that a GP is supposed to be used with a low horizontal blade angle. You certainly don't find this in Greenland. For regular touring I hold the paddle at about 45 degrees and for sprinting the paddle goes as vertical as possible for the best speed (at the expense of more effort and arm-lift). I assume you are using the canted blade technique (top edge of blade tilts forward), as it adds extra power to the stroke.
"I also don't see why a wider grip with a gp would stress the shoulders".
With any paddle a wider grip allows more independent arm motion (if you are an arm paddler) and gives a greater feeling of power, but requires more arm lift to achieve a vertical blade. That means that in addition to the weight of your paddle you are lifting more pounds of muscle and bone per stroke. This isn't significant on a sprint or even a 10 miler but adds up over the miles. For endurance activities (high mileage days) I recommend to hold the paddle with a slightly narrower grip (only as wide as needed to have sufficient power and leverage) and adopt a technique that doesn't require a high "chicken wing" lift of the elbows.
"The one arm plus a cubit means of setting length seems foolish to me. There is no substitute for trying different dimensions to see which works best one's particular body, stroke style and boat".
It's the most common measuring technique in Greenland. It is a shorthand that takes into account your arm-span and assumes you have a "Greenland-style" kayak; low decks and a width of one fist on each side of your hips. Even in Greenland this is considered a *rough guide only*. Final size is always determined by experimentation, testing and personal preference. At some point as your kayak gets further and further away from a "real" Greenland kayak (picture an Anas Acuta as a LARGE Greenland kayak) you have to start modifying the paddle. At some point of beamy kayak and high foredecks "all-bets-are-off" as it isn't a Greenland kayak anymore and it isn't a Greenland paddle.
"For an efficient forward stroke, whether gp or whatever, a slightly wider grip just seems better to me, whether racing or not. Around 24" loom, as the racers that you describe use, is about right. Maybe not for rolling, I don't know".
Turner Wilson uses a 24-25" loom on his GPs. So does Maligiaq. The paddles I use with an Anas Acuta, Tahe Greenland, etc, are 22". There's plenty of room for personal variation. You need a long enough shaft that you can fully bury the blades (water up to your pinky on the pulling hand), while maintaining good posture. I see a lot of people paddling hunched forward with a (too short loom) GP as it is the only way they can fully bury the blades.
Greg Stamer