Bent shaft paddle technique question

Thanks for the comments
I was in the 15’ mad river freedom discussed in an earlier post. I was doing fine with j stoke and forward momentum with the straight paddle but didn’t have time to dial in the bent shaft paddle as I had to keep up with a large group.



The paddles were the same length, my wife uses a bent shaft that is several inches shorter than my straight but I have done too many air sweeps with it which do nothing but amuse the fisherman.



I’ve got some seat time in a lawn chair, switching between paddles and looking back at the blades ( and getting That Look from wife and daughter) to see what was going on and looking forward to getting out on the water again with it.

Stance, Paddle formats

– Last Updated: Jun-17-14 7:36 PM EST –

John Winters did research in the early 90s indicating that paddle blade loose effectiveness when more than 10dg off square to the stroke. [Rowers suggest 20dg, averaging the two studies leaves us with a +/- 15dg effective window.]

Straight paddles square to the stroke forward of the paddlers knee, a range of motion most easily used when kneeling. Bents +/- window starts just before the knee and ends at the hip. The roughly "along the thigh" stroke is easily accessed by sitting paddlers.

The J requires powering the stroke past the torso, which creates yaw, turning the boat off course. Yeah, the J corrects for the turn it just creates, and it also slows cadence, which, in turn, slows forward progress.

Of course one can J stroke with a bent. It isn't as effective as J with a straight blade because the bend is already close to the end of the +/- 15dg "window" The larger question is the use of the J stroke.

Kneeling paddlers are better off correcting with cross forward strokes. Sitting paddlers are lower in the boat and less able to employ cross strokes, so switching sides is more effective bio-mechanically. In both situations, the paddle is operating within it's effective window and cadence is higher, both contributing to greater efficiency.

It seems Hull Trim is another factor for the OP. Solo paddlers in symmetrical hulls need the seat's front bar ~5" aft of center when kneeling, ~2" aft of center when sitting, the location of the paddlers belt buckle, ~7" forward of seat front bar for kneelers, ~7" aft of the bar for sitters and some weight of the out-stretched legs accounting for the seat placement difference. Sitters need a foot brace or pegs to establish bone to boat contact.

Kneeling versus sitting seat placement
I’ve seen this advice a lot, that kneeling paddlers should be a little farther behind center than sitting paddlers, but I don’t understand the reasoning. A sitting paddler with outstretched legs has a center of gravity that is farther forward in relation to the seat location than that of a kneeling paddler. It would seem that if weight distribution and trim were the only issue of concern, a sitting paddler would want his seat a little farther back than a kneeler. Maybe there’s some other reason for this advice.

yes, I agree with you there
I have found that for symmetrical hulls in order to trim the boat neutrally for me in a kneeling posture my hip joint needs to be centered about 4 1/2" aft of the longitudinal center. My navel, or where my navel used to be, winds up right about at the longitudinal center or very slightly forward of it.



I think this placement might be different for different people. Those with very long femurs probably need to center the torso slightly more aft.



In a sitting posture I need to have my torso positioned at least a few inches further aft.

I agree with GBG and Pete
It seems that my sitting boats ( ie the RapidFire) have the seat positioned quite far back compared to my kneeling solos.



So I too am in the confused room. I do understand the principle that larger people may need a seat placement farther back in order to maintain good steering control. Gut too far forward is not a happy thing.

Trim thoughts

– Last Updated: Jun-17-14 7:38 PM EST –

'didn't mean to get technical with trim, but if OP's bow is light he probably needs to move forward quite a bit in his hull.

Trim is affected by hull form: Swede form, symmetrical, Fish form.
Trim is also affected by paddler physique; body parts with forward overhang locate the CG further forward of the spine.
Trim is affected by stance in the boat, the location of the belt buckle relative to the seat bar and big feet forward move paddler CG.
Trim is affected by paddler effort, greater effort lifts the bow more, suggesting more forward CG placement.

When I was setting trim at Bell, the machine screw drill hole was placed 6" aft of Longitudinal Center for Flash and Wild, both symmetrical bottoms, resulting in the seat's front bar being 4.5" aft of Center. This worked fine for me, as I was once skinny and paddled aggressively. DY, less aggressive with the paddle and with more success overhanging his belt thought the seat was an inch too far forward.

Best way for folks to gauge trim is to dump a quart of water in their boat. It should be visible forward at rest but move aft some when underway, all varying with hull form and rocker and the designer's intent.

Bow light
I was actually thinking that in an upstream situation on a long straight stretch of river a little bit of bow heavy would have held me on track, a technique I sometimes use when kayaking to deal with winds or seas running bow on or from straight astern, the weather vane effect. If I would have had my typical gear bag I would have chunked it towards the bow but I was traveling light in a relatively short paddle with a hundred other paddlers and chase boats.



A couple weekends ago I was in a Mohawk solo running downstream in a situation requiring lots of maneuvering and found my self wishing the seat was further aft as I could not get the bite I needed to bring the bow around as fast as I wanted using sweeps and spent alot of the paddle kneeling at the thwart doing bow strokes to maneuver. I wish I had paid attention to the water in the bottom of the boat, that is an excellent suggestion for monitoring trim.

Current direction and trim

– Last Updated: Jun-17-14 7:06 PM EST –

One thing that some people realize and some people don't, is that in non-turbulent current, it makes no difference which direction you are traveling. When going upstream, it's easy to notice that veering off-course seems more extreme than when the same thing happens going downstream, but in non-turbulent flow, it only looks that way because in both cases you are relating your boat's progress to fixed landmarks, and your speed of travel in relation to those landmarks is slower when going upstream, so the turning action seems more abrupt when going upstream as well. The interaction of the hull with the water that supports it is the same in either case, which could be demonstrated if you had some way to leave a trail of floating "breadcrumbs" behind you. The best example of this is how kayakers far from shore will only know the effect of a strong current by looking at their GPS - and they may find they are going diagonally or even backward, all while they are watching the water streaming by their hull as they go straight ahead within the water that supports them. Bottom line is that in the absence of noticeable turbulence, trim need not be adjusted according to paddling direction. Poling a boat is a whole different situation, where the boat is held against the current by contact with the solid river bottom, and wind makes a difference for the same reason in that there's a force acting on the boat that is NOT due to pushing against the same water that supports you.

On the other hand, turbulent conditions can present a different problem, especially when the boat is going upstream and suddenly enters a zone of stronger flow than the water it was in just a moment ago. Worse, during the transition between flows, the boat is at equilibrium in the old flow but not the new one (the effect is like stepping onto a moving conveyor belt and losing your footing, or stepping off a slow-moving car onto the ground and having the same thing happen). That's a case where the bow can get "grabbed" and you get yanked off your heading, and for the few seconds it takes for the boat's momentum to be overcome so that it's at equilibrium in this new flow, the handling is all messed up as the water goes rushing by the hull at a funky angle, but a few seconds later, all is well again (oh, and you can take advantage of this situation too, the classic case being a "jet ferry", which is something that only works during the time prior to the boat's momentum being overcome and being at equilibrium with the current again). Being bow-light will be an advantage in that case as you cross those boundaries between different speeds and/or direction of flow.

When sitting, you’re back on the seat
farther than when kneeling. When kneeling, my butt’s probably only half way back on the seat, if that much.



Maybe that’s the real difference in seat placement to maintain similar trim when sitting or kneeling.

RapidFire Seat location specs

– Last Updated: Jun-17-14 8:26 PM EST –

Placid's Rapidfire, a mildly Swede-form hull, is 180 inches long, so the center is 90in aft of the molded bow. The arc to the floor, from the 17" bow is ~ 91in from molded bow. The arc from bow to the front of the seat rim was located at a 90" arc from bow. The angle of seat sidewall taper to the seat's front edge is about an inch, so the molded seat's front edge is pretty much exactly at longitudinal center with the seat extending aft of that point.

This location is similar to WeNoNah's but we arrived at it independently, with a quart of water in the bottom and a pencil.
Both Joe and I are slender, the paddler's belt buckle, based on my conformity, ~3.5-4in aft of the seat edge. It's possible we sited Kim's seat a little aft, but the records burned in the great fire of January 2013.

In my particular case the seat is
canted to throw weight back… There is a very different feel when the seat is canted to more of a level surface as in the drop in high pedestal seat.



I do feel the difference in handling. Perhaps its an illusion. I have fallen out of my DragonFly twice today while taking eagle picture… so nothing I say now can be trusted.

Placid Seat Angles

– Last Updated: Jun-17-14 11:26 PM EST –

We're quite some distance from OP's questions, but;

Placid's low seat has a 12 dg back angle, the medium an 8 dg back angle and the high a 4dg back angle. I know this because I tooled them; just checked my notes.

Actual CG placement comes down to posture?

yah the OP is probably out paddling
but I took the heights off the PBW website.

Remember
Stacking raises seat height about a half inch higher than when it is glued down due to friction fit of the tapered sidewalls. In theory, the front height is about the same, the back is raised/back angled less from low to high.

I’ll show you my ignorance
of bent shaft paddles. My advice would have been to only use it in the bow position for power. Leave the steering to the stern and someone using a straight shaft paddle unless you’re hitting and switching to maintain course. Clearly, in the last 30 years, the racing community has pushed the sport into new territory and new techniques have evolved.

Doesn’t work

– Last Updated: Jun-18-14 10:49 AM EST –

As discussed above, for optimal performance kneeling paddlers should use straight paddles, sitting paddlers bents. OK, OP was discussing solo paddling, but the stern can kneel while the bow sits for tandem work.

But, cadence is off. The catch, propulsion, recovery phases of straights and bents is off. Matching catch is an obvious start point, but the power pulses then do not match. The boat rolls a little, inducing small on and offside carves which wreck tracking and efficient water-flow past the hull.

To optimize performance, tandem teams need be on opposite sides and in cadence with their paddleshafts vertical in the water, strokes isolated in forward of the body. Stern Js mostly correct for the stern carrying the blade aft of the body into a sweep. The stern's sweeping conclusion turns the boat onside, towards the bow's paddle side. The J cranks it back offside, again creating little on and offside carves that destroy tracking and forward speed. Worse, the J takes the stern out of cadence and starts the hull rolling. Best not to do that, it causes frustration and, maybe, divorce!

Last night
I went out for a paddle after reading this thread and did some J stroking just to see how our discussion lines up with what I observe.



Overall, I feel I can do an effective J stroke in my solo with a 12* ZRE bent shaft, however it seemed very inefficient compared to sit and switch. I know there are many reasons to do single sided paddling, but for the most part, I preach sit and switch for life! I mostly do J strokes when Im with the wife and just want to slowly cruise. If Im trying to cover ground, no j stroke is the best j stroke.



Also, I had never done a thumbs up j stroke, I always did a thumbs down stroke. The thumbs up is basically a rudder, right? Good to have it in the quiver though. there have been a couple times that I could have used the rudder J had I known about it.

Thumbs up J stroke
The thumbs up J stroke, aka goon stroke, aka modern J stroke, aka river J stroke is basically a forward stroke followed by a stern pry.



Yes, in terms of paddle blade placement and grip position the conclusion is pretty much the same as what some folks call a stern rudder. I think of a stern rudder more as a paddle position in which either the back face can be loaded for a static or active stern pry, or the power face can be loaded for a static or active stern draw, or both can be done alternatively as when bow surfing on a wave.



The advantage of the thumbs up J stroke is that the pry portion has much greater mechanical advantage and is thus much more powerful which can be very useful when getting turned to the off-side in current, or when executing an upstream ferry with the paddle on the upstream side of the boat, or when starting from a dead stop. It does not work terribly well with a bent shaft paddle unless you invert the blade, however.

“Modern J stroke”?
Haha. Terminology is such fun.



More accurately, it’s likely the original Neanderthal J stroke.

It’s impossible to not interfere with

– Last Updated: Jun-19-14 10:46 AM EST –

canoe momentum if one doesn't flip the paddle blade sidways(ie recovery phase..ala j-stroke style) for smoother passage through the water. If the correction phase is slow, that's the paddler's fault NOT the paddle's or "J's" fault. If one begins with a bit of sweep...of course the correction will incorporate more correction = slowing of momentum...but again, that's the paddler's fault people. If you haven't worked on your correction phase(J phase) then put a bit of draw into your paddle-plant..but don't waste time after you get the paddle in the water. Quicken the time that it takes to plant the blade in..then initiate the pull with a little bit of draw. That's the time of lost momentum and that helps a LOT in finishing the stroke without much need for a lot of correction.