Edging - how does it work etc^

Places, technique, kayaks, safety, the sea...
dpround
Posts: 199
Joined: Tue Nov 16, 2010 9:57 am

Edging - how does it work etc^

Post by dpround » Fri Nov 26, 2010 12:27 pm

The discussion of stability i the Tiderace thread was fascinating. I wonder is someone wouldn't mind expanding this into how edging works. In a sailing boat you tip the boat *away* from the direction you want to turn in order to use the shape of the hull to turn with maximum efficiency instead of ramming it round with the rudder. Initially I was puzzled that kayaks tip in to the turn when edged. I think now that the reason for edging a kayak this way is not related to using the curves over the hull length, as it is in a sailing dinghy, but changing the section of the hull in the water and possibly changing the water line length. (One reason is that the curves along the length of a kayak are much slighter due to the much greater relative length and so the effect will be small.) With playboats all that seems to be required is to get the outside rail out of the water, which frees the boat to slide. Is the aim with a sea kayak to get the keel to the surface of the water?

Are there any measurements that can hint how far a kayak needs to be edged to turn efficiently and how easily it will turn then?

Thanks in advance

David

User avatar
TechnoEngineer
Posts: 3292
Joined: Mon May 12, 2008 7:47 pm
Location: Berks, Hants, Essex

Re: Edging - how does it work etc

Post by TechnoEngineer » Fri Nov 26, 2010 12:44 pm

There are different types of hull - planing and displacement, and the amount of chine also has an impact.

Generally, whitewater boats tend towards having planing hulls with hard chines (especially surf kayaks) so they "carve" turn towards the side that's submerged.

Generally, sea kayaks have displacement hulls, which turn away from the side that's submerged, due to the different lengths of hull in the water. You certainly don't want the keel to surface, typically you can heel it by around 30 degrees before you fall in (if the Sea Kayaker stability reviews are to be believed).

Having more rocker also allows the boat to turn more easily.
XL-Burn-3 / Monstar / Kodiak / My Videos

GrahamKing
Posts: 199
Joined: Tue Mar 20, 2007 7:31 pm
Location: Teddington, Middx.

Re: Edging - how does it work etc

Post by GrahamKing » Fri Nov 26, 2010 2:24 pm

dpround wrote:... In a sailing boat you tip the boat *away* from the direction you want to turn...
With sailing boats, when you heel the boat, the centre of effort of the rig moves outboard, creating a turning moment. Years ago, when I worked as an instructor, we used to race each other round a triangular course, rudderless, using this effect. A corollary is that, when you're close-hauled, you get extreme weather-helm unless you hold the boat on an even keel.
Is the aim with a sea kayak to get the keel to the surface of the water?
Yes, that's part of it. By disengaging the ends of the keel, you make the boat easier to turn. Leaning and edging are, to some extent, inseparable (owing to the righting moment of the hull), so edging towards the outside of a turn also increases the paddle's reach and thereby increases its turning moment (try it both ways to see the difference). My suspicion is that this effect dominates the variable effect of different hull shapes, and leads to the belief that "sea kayaks turn away from the direction of edging."

User avatar
TechnoEngineer
Posts: 3292
Joined: Mon May 12, 2008 7:47 pm
Location: Berks, Hants, Essex

Re: Edging - how does it work etc

Post by TechnoEngineer » Fri Nov 26, 2010 2:38 pm

Not sure about that Graham - I'll often drift with the boat on edge to turn it; no sweep strokes or such required.
XL-Burn-3 / Monstar / Kodiak / My Videos

User avatar
nickcrowhurst
Posts: 1012
Joined: Sun Aug 06, 2006 11:07 pm
Location: Cornwall, between swims.
Contact:

Re: Edging - how does it work etc

Post by nickcrowhurst » Fri Nov 26, 2010 2:47 pm

In sea kayaks we will use inward or outward edging, or a combination, as befits the purpose. For example, in low brace turns we can initiate the turn by edging away from the intended turn, and doing a sweep stroke on the low side. When the turn is initiated, we can flick over to the other edge with the paddle in the low brace to complete the turn. Either way, the aim is to make the kayak directionally unstable by changing its underwater profile. At least, that's how my Gran always explained it to me. Back to the shed.
Nick.

User avatar
PeterG
Posts: 754
Joined: Thu Mar 09, 2006 4:36 pm
Location: On the water, or in the woods

Re: Edging - how does it work etc

Post by PeterG » Fri Nov 26, 2010 3:24 pm

My boats, Aa and Tahe marine Greenlander, both hard chined, are very responsive to edging. Outside edge, either as a gentle continuous edge to correct weather-cocking (or lee-cocking in the Greenlander if you have the skeg right down) during what looks likely to be a short lived windshift so you don't want to alter the skeg setting, or a more definite movement to initiate direction change. This is to do with altering the shape of the wetted area. You can balance the paddle on your head, the boat still turns rapidly.

Once the boat is right over on its side it will alter course rapidly because of the shortened waterline and it doesn't matter which side, but usually it is combined with a low brace so leaning into the turn is natural. In this case the paddle might be further outboard and so contribute to the increased turning effect, I suppose that a sweep stroke combined with edging away from the turn does have the same effect.

However, either on its own or combined with bow rudder close to the hull, edging out undoubtedly turns the boat. With an ocean cockpit and knee bumps, gentle knee pressure is all that is required.

In real life, the boat always turns, apparently by itself, in the direction you are looking or thinking about going in. It must be controlled by unconscious body movements, though it is easy to start believing that your beautiful boat has an intelligence of its own.....

User avatar
Jim
Posts: 13497
Joined: Sun Apr 21, 2002 2:14 pm
Location: Dumbarton

Re: Edging - how does it work etc

Post by Jim » Fri Nov 26, 2010 4:04 pm

Graham's point about the CE moving outboard in a sailing boat is a good one - it's basically the same effect as the increased reach on the low side of the kayak.

I have decided from quite a bit of thinking and trying, that there are several factors influencing which way a sea kayak turns when edged.

Some boats naturally turn to the side away from the edge, some the other way (do chines make a difference?)
Some people either increase their reach on the low side, or shorten it on the high side which creates a moment which will tend to turn the boat away from the edge. Other people don't
If you try edging without paddling happens? Does it depend on which side you took your last stroke before edging?
If so, is it perhaps it is the case that depending on whether the last stroke before/as the edge is applied was on the same or opposite side the boat will turn one way or the other (once the turn is initiated it the edge simply helps no matter which edge it is?)

The points that are for certain, are that edging reduces waterline length and increases rocker (the pivot is deeper and thus bites harder, as well as the ends rising clear).

What is less certain is how much hydrodynamic 'lift' you get from the asymmetric underwater shape and in which direction it will be acting.
Also where you dip a deck edge or chine (or release a chine) you are going to alter the drag caused by flow seperation off that edge - what effect does that have?
Are all these effects significant compared to the influence of the paddler? or is it simply a case (as theorsied a paragraph or 2 ago) that once the paddler has initiated the turn the hydrodynamics are weaker and the boat will carry on turning that way regardless of which edge is up and which down?

Edging to counter wind, now how does that work? Mostly I'm certain that I drop the edge away from the wind to keep my boat turning slightly upwind as I paddle normally, but the chances are I am getting the extra reach on the downwind side coupled with the extra rocker to help me create a yaw moment resisting the one from the wind. Can I really tell? Well the sea usually isn't dead flat when I'm edging against the wind and that is bound to add extra complication, so no I can't tell!

If the hydrodynamics are significant, how does that alter when you paddle the boat empty vs loaded? Has anyone ever noticed that a boat seems to respond to the edge in the opposite manner when fully laden?
What about when you are paddling in a tide stream or current? Does the hydrodynamic effect from that make the boat handle differently than in still water?

To be honest, with so many possible factors, I would suggest just trying edging and do whatever is most comfortable or seems most effective to you. Don't worry if you are edging the opposite way to your friends, I mean by all means if they all edgethe opposite, give it a try and see if it feels better, but if not don't feel that they are right and you are wrong - you may all be right or all be wrong :-)

By default I edge to the outside of a turn, but in tests, rather like the direction of water swirling down a plug hole, I can make it turn either way with either edge.

Sprucey
Posts: 152
Joined: Thu Sep 17, 2009 4:37 pm
Location: Langstone, Hampshire

Re: Edging - how does it work etc

Post by Sprucey » Fri Nov 26, 2010 4:39 pm

I'm an ex sailor and am convinced that the major reason for edging is the assymetric shape the edged hull presents to the water, combined with a shorter waterline length allowing the boat to pivot more easily.

I used to sail the Finn dinghy, the Olympic heavyweight's mens single hander. In the old "FinnFare" class magazine there was a brilliant article where someone had taken underwater shots of a hull in a swimming pool - demonstrating the assymetric shape of the hull when heeled (edged) on each side.

Leaning the rig will move the COG of the rig (and boat) off-centre but in roll tacking and gybing, that is used more to effect the heel easily to turn the boat quickly without excessive rudder movement (causing drag) and to make sure the rig is to leeward when the manoever is completed allowing the boat to be rocked/pumped/roled quickly back upright, creating apparent wind over the rig and accelerating the boat out of the tack/gybe.

In light airs, heeling the boat to leeward adds some weather helm to give "feel" to the helm, the assymetric shape makes the boat go to windward with less rudder (as mentioned above) and the shortening of the water line (aided by moving crew forward) helps reduce wetted surface area, lifteing generally flatter, draggy aft sections out of the water. In addition, it helps the sails "fall" into some shape.

Your sea kayak is not much different.

Sprucey

User avatar
Jim Tait
Posts: 220
Joined: Thu Oct 27, 2005 10:23 pm
Location: Shetland

Re: Edging - how does it work etc

Post by Jim Tait » Fri Nov 26, 2010 6:03 pm

TechnoEngineer wrote:There are different types of hull - planing and displacement, and the amount of chine also has an impact.

Generally, whitewater boats tend towards having planing hulls with hard chines (especially surf kayaks) so they "carve" turn towards the side that's submerged.
I've found over the last couple of weeks that edging a surf boat away from the turn leads to me exploring my tertiary stability!! [holding breath smiley]

Jim

User avatar
Robert Craig
Posts: 665
Joined: Tue Aug 23, 2005 8:55 pm
Location: Glasgow

Re: Edging - how does it work etc

Post by Robert Craig » Fri Nov 26, 2010 6:21 pm

I'm assuming that in this thread "turning" means "turning a sea kayak by forward sweep strokes, while maintaining forward progress through the water."

It's easy to demonstrate that all sea kayaks "turn" with least effort - ie with fewest strokes - when on an edge.

It's also easy to demostrate that the majority (maybe all) turn with least effort when edged so's to lean out (ie the opposite way from a bicycle). It was pointed out to me (by Tony Hammock) that the reason is obvious - leaning this way allows a more effective sweep stroke, with the paddle further from the boat and so more turning moment. There may be effects as well from the different underwater shape of the boat, but these other effects are small compared with the large effect of getting much more welly in the sweep stroke.

rockhopper
Posts: 677
Joined: Mon Oct 02, 2006 7:55 pm
Location: Essex

Re: Edging - how does it work etc

Post by rockhopper » Fri Nov 26, 2010 6:48 pm

I don't think a stroke of any kind is necessary to turn a boat (but it certainly helps hugely and can determine which direction the boat turns). For instance, if I paddle my Alaw Bach (which is soft chined) as fast as possible, leave it to coast in a straight line (so that a paddle stroke is not affecting its turning) and then edge the boat then it will turn. If the boat is going fairly quickly it will turn to the outward edge however if it is going slowly it seems to prefer to turn the the inside edge.
On the other hand, when I recently paddled an Anas Acuta (hard chined) it seemed much happier to turn to the outside edge, even at slower speeds. Not having paddled the AA very much I am still experimenting with how different its characteristics are from my normal boat.

Rog.

User avatar
PeterG
Posts: 754
Joined: Thu Mar 09, 2006 4:36 pm
Location: On the water, or in the woods

Re: Edging - how does it work etc

Post by PeterG » Fri Nov 26, 2010 7:18 pm

Pick up a bit of speed in the Anas acuta on flat water, put your paddle on your head, or just hold it clear of the water and try edging. It will turn away from the buried edge and you can do a slalom course as long as you are gentle; edging works.

However, edge hard, allow the turn to harden and it becomes impossible to get the boat to straighten up. Opposite edge and the turn intensifies still further. Level running slowly reduces the turn. Inertia and the reduced waterline effect has taken over.

Making best use of both effects can be handy if the skeg is jammed in a side wind, a jerky sort of extreme edge away from the wind on top of a wave, and the boat swings away from its weathercocking course more effectively than using a steady gentle edging. Combined with a strong stroke with a hint of sweep on that side and you are running downwind!

User avatar
Mike Mayberry
Posts: 804
Joined: Thu Nov 01, 2007 5:13 pm
Location: Pembrokeshire
Contact:

Re: "Edging - The Black Art"

Post by Mike Mayberry » Fri Nov 26, 2010 7:31 pm

When I paddle my NDK Greenlander with chines, I can paddle it forwards, stop paddling, edge to the right and it will turn to the left. If I then change the edge (without recommencing forwards paddling) it will change direction. This tells me that the shape of the hull in the water effects the directional stability of the kayak. Sailing has been mentioned as an analogy, I used to love balancing the sail and my weight to steer a dinghy with no rudder. Rowers all sit in the middle of the boat because if the boat lists to one side then the cox will use the rudder to compensate the turning and therefore be less efficient. If I try the same edging exercise in my Tempest (not chined) then the original turning direction will be maintained after the edge change. This assumes my body facing forwards, particularly the upper torso as....

When rotating the upper body in one direction the legs want to turn and point the same way. This lower body pressure creates the drive to make a kayak turn. Try it in a river kayak that fits correctly that is not travelling anywhere. Take a sweep stroke an leave your upper body rotated to the direction at the end of the stroke. Note how far the kayak turns. Now repeat the sweep stroke exactly as before but this time, once you have reached the stern, rotate your upper body to the direction of the turn and notice how much further your kayak turns.

Using this rotation in my Tempest makes it very manouverable. I can initiate the turn with an outside edge and then change to an inside edge combined with a bow rudder/ draw and swing it around between the rocks quickly, with little effort and against some swell. The legs driving the turn.

Someone mentioned edging sufficiently to get the keel to the surface of the water. This will change the profile of hull in the water and effectively give you a flat surface that can skid across the surface. This is the amount of edge I am committing to in the above paragraph. Perhaps it helps to have come from a river background but there is an enormous amount of support to be had from that bow rudder/ draw stroke.

It is true that when you edge a kayak you can reach out further with your strokes on that same side, this is a basic turning stroke that most people know. For my wife this is her only method of turning despite three good coaches trying to convince her there are more efficient methods that can be used alongside it!

The reality is that to turn a kayak there are many methods and it's important to to learn and master them all so that you can use parts of each at the right time, in the right place to create the desired effective turn.

geoffm
Posts: 386
Joined: Sat Oct 29, 2005 5:05 am
Location: Tasmania
Contact:

Re: Edging - how does it work etc

Post by geoffm » Sat Nov 27, 2010 7:08 am

One pointer to the hull shape having a direct influence when edged is when I am sailing my kayak (using one of the recently much publicised Flat Earth Kayak sails) I can control the direction the kayak turns purely by edging and letting the sail provide the motive force. Once the sail angle and skeg are balanced for straight line travel edging controls the minor direction corrections.
Of course, the other points raised all have a contributing influence including constant foot pressure on one side, unconscious body changes (look where you want to go etc) and a heap of other stuff so it is a remarkably complex process.

Geoff

User avatar
Kim Bull
Posts: 113
Joined: Mon Dec 21, 2009 12:39 pm
Location: Northumberland
Contact:

Re: "Edging - The Black Art"

Post by Kim Bull » Sat Nov 27, 2010 10:18 am

Mike Mayberry wrote:
When rotating the upper body in one direction the legs want to turn and point the same way. This lower body pressure creates the drive to make a kayak turn. Try it in a river kayak that fits correctly that is not travelling anywhere. Take a sweep stroke an leave your upper body rotated to the direction at the end of the stroke. Note how far the kayak turns. Now repeat the sweep stroke exactly as before but this time, once you have reached the stern, rotate your upper body to the direction of the turn and notice how much further your kayak turns.
Hello Mike. I'm really curious about this concept of lower body pressure. I haven't tried this exercise so will go and test it - thank you. I have found that every action has an equal and opposite reaction (although I think Newton got there before me!). If I sit stationary in my river kayak and without placing my paddle in the water, if I rotate quickly to my right the kayak turns to my left. I wonder if there are more variables at play which result in your findings?

My current thinking is that lower body pressure is more about achieving appropriate connectivity to allow a summation of forces and biomechanical efficiency. For example, for a low brace turn I push harder with the foot on the inside of the turn while in the low brace position, for a bow rudder and opposite edge I push harder with the foot on the outside of the turn, for a stern rudder I push harder on the foot on the paddle side to assist with rotation.

Rather than thinking that if I rotate my body in one direction my legs want to follow, I now often find it more useful to think that if I want to rotate my body I'll do that by pushing with a foot and rotating my hips and trunk together.

Interesting stuff!
Very best regards,
Kim
www.kimbull.co.uk
Excellence in Canoe and Kayak Coaching

tg
Posts: 827
Joined: Thu Jan 24, 2008 6:51 pm
Location: Pennyhole Bay

Re: Edging - how does it work etc

Post by tg » Sat Nov 27, 2010 10:23 am

Hi David,

Gosh! What a large can of worms you cracked open there, Trim, trim, trim. I think it's a learned instinct, if that doesn't sound contadictory (I know ... it does!). If you take the hull form as a given ie; you'll be paddling the same boat all, or nearly all, the time, then you can experiment. Shifting your weight; rotating you body, putting all the heavy kit forward, aft, port, or starboard, or fiddling with your skeg depth, will effect the characteristics of your hull in the water. This can exacerbate or reduce the effect of unfavourable (or favourable!) sea or weather conditions. What you learn in one hull will serve as a baseline for other boats and other hull forms.

I'd say it's well worth the effort of getting to grip with these ideas. It will make your paddling more pleasant.

Ray of the telly did a program about open canoe expeditions in North America and made the point that they would often paddle for an hour or so and then stop have a bevvy and a snack and repack the boats, trim, I reckon.

It's worth a look at paddling technique in open canoes. The effect of edging is really obvious.

Tim
"I sink therfore I am".

User avatar
Mike Mayberry
Posts: 804
Joined: Thu Nov 01, 2007 5:13 pm
Location: Pembrokeshire
Contact:

Re: Edging - how does it work etc

Post by Mike Mayberry » Sat Nov 27, 2010 12:10 pm

Kim Bull wrote:Hello Mike. I'm really curious about this concept of lower body pressure. I haven't tried this exercise so will go and test it - thank you. I have found that every action has an equal and opposite reaction (although I think Newton got there before me!). If I sit stationary in my river kayak and without placing my paddle in the water, if I rotate quickly to my right the kayak turns to my left. I wonder if there are more variables at play which result in your findings?
Hi Kim, I have proved to many students that the upper body rotating in the direction of the turn helps a kayak to keep the momentum of the turn, I've lost count of the number of people that have gone "oh yeah"! I suggest trying it in a river kayak only because they are more responsive to this, but it still transfers across to a sea kayak. There was someone on the inland forum who didn't believe that the skills we use to turn one boat will apply to another but it is how I'm able to paddle a sea kayak one day, a river kayak the next and then go surfing on my time off.
My current thinking is that lower body pressure is more about achieving appropriate connectivity to allow a summation of forces and biomechanical efficiency. For example, for a low brace turn I push harder with the foot on the inside of the turn while in the low brace position, for a bow rudder and opposite edge I push harder with the foot on the outside of the turn, for a stern rudder I push harder on the foot on the paddle side to assist with rotation.
Is the pressure greater on the inside foot because you have dropped that edge, therefore the knee pressure is less on that side and the leg slightly straighter? The knee on the upper edge has greater pressure and that is driving the turn? I use bow rudders and low brace turns with both inside and outside edge turns to differing effects. Regards to the foot pushing harder on the same side as a stern rudder, is that because rotating to reach the stern has caused that edge to drop slightly and you are counter balancing it in order to steer straight? I would venture the answer to all of these questions as being yes.
Rather than thinking that if I rotate my body in one direction my legs want to follow, I now often find it more useful to think that if I want to rotate my body I'll do that by pushing with a foot and rotating my hips and trunk together.

Interesting stuff!
Indeed it is! :)
tg wrote:Trim, trim, trim.
Just to throw another spanner into the works! Having tried the first exercise, now paddle forwards and initiate a turn (including everything we've been through), with your body in three postions, upright, forwards and slightly backwards. Each will give a different result to the type of turn. Be sure to keep all other things equal each time so as not to flaw the results.

User avatar
Kim Bull
Posts: 113
Joined: Mon Dec 21, 2009 12:39 pm
Location: Northumberland
Contact:

Re: Edging - how does it work etc

Post by Kim Bull » Sat Nov 27, 2010 5:40 pm

Mike Mayberry wrote:
Hi Kim, I have proved to many students that the upper body rotating in the direction of the turn helps a kayak to keep the momentum of the turn, I've lost count of the number of people that have gone "oh yeah"!
Hi Mike,
I wonder if you have any ideas to help me understand why they might have experienced this? Newtons third law (every action has an equal and opposite reaction) seems to suggest that if we contract muscle groups and cause a part of our body to rotate (eg our upper body into a turn), then the equal and opposite reaction will cause the other part of our body to rotate in the opposite direction(ie our legs and therefore boat against the turn). I'm not sure if it's the rotation in the direction of the turn that helps your students maintain momentum, but perhaps some other coincidental factors? I'd be interested in understanding this further.
Is the pressure greater on the inside foot because you have dropped that edge, therefore the knee pressure is less on that side and the leg slightly straighter? The knee on the upper edge has greater pressure and that is driving the turn?

For me, the purpose of the foot pressure is to initiate body rotation towards that side of the boat. This in itself doesn't result in a dropped edge, but does have the benefit of setting up my connectivity (raised knee on opposite side) to allow efficient edge control. And for me, the greater knee pressure doesn't drive a turn but does provide positive connectivity which allows my full body to drive the turn.
Regards to the foot pushing harder on the same side as a stern rudder, is that because rotating to reach the stern has caused that edge to drop slightly and you are counter balancing it in order to steer straight? I would venture the answer to all of these questions as being yes.
Again, not for me as I push with the foot in order to initiate rotation, not to control edge after rotation has occured.

I've come to my current way of thinking by taking forward paddling (planting the blade, pressing with the foot on the same side and 'unwinding' the whole body from the foot up) and applying those same principles to the other techniques we use. It's a shame we're so far apart - I'd really enjoy you taking me through your current thinking and having the opportunity to take you through the concepts as I understand them at the moment. Perhaps you'd be interested in a short video which might explain how I use foot pressure for transfering power here?

Very best regards,
Kim
www.kimbull.co.uk
Excellence in Canoe and Kayak Coaching

User avatar
Mike Mayberry
Posts: 804
Joined: Thu Nov 01, 2007 5:13 pm
Location: Pembrokeshire
Contact:

Re: Edging - how does it work etc

Post by Mike Mayberry » Sun Nov 28, 2010 11:18 am

Hi Kim,
Kim Bull wrote: I wonder if you have any ideas to help me understand why they might have experienced this? Newtons third law (every action has an equal and opposite reaction) seems to suggest that if we contract muscle groups and cause a part of our body to rotate (eg our upper body into a turn), then the equal and opposite reaction will cause the other part of our body to rotate in the opposite direction(ie our legs and therefore boat against the turn). I'm not sure if it's the rotation in the direction of the turn that helps your students maintain momentum, but perhaps some other coincidental factors? I'd be interested in understanding this further.
This is down to the way in which our body is connected together, more specifically, due to the ilipsoas muscle. This muscle is joined to the spine on either side up as high as the rib cage, runs inside the pelvis and joins onto the thigh bone. If i were to stand and lead with the hips, or sit and push with one foot my hips rotate a few degrees and the shoulders do follow, only to the same point as my hips, ie. they stay in line with each other. If I repeat this but lead with my shoulders then I can rotate them much further, past the rotation of my hips. This tells me that my spine has wound up like a coiled spring and is inwinding through my legs. Therefore, rotating the shoulders into the turn, twists the spine to that direction and so the hips and legs follow.

Image

A golfer utilises this muscle in his swing by leading with the hips and creating a "snap" with the shoulders. As kayaker we use it the opposite way around. Snowboarders, skateboarders etc., all use the same principle to initiate moves. I think that Newtons third law can apply to the muscles in our body rather than the upper and lower parts. ie. the muscles on one side contracting and the opposite side extends.
Kim Bull wrote:I've come to my current way of thinking by taking forward paddling (planting the blade, pressing with the foot on the same side and 'unwinding' the whole body from the foot up) and applying those same principles to the other techniques we use. It's a shame we're so far apart - I'd really enjoy you taking me through your current thinking and having the opportunity to take you through the concepts as I understand them at the moment. Perhaps you'd be interested in a short video which might explain how I use foot pressure for transfering power here?
It is a shame we are opposite ends of the country. I grew up in East Anglia and found when I moved here 15 years ago that there were many different ideas here to those I can been shown whilst learning. It was a great time, sharing and learning new methods. I'm sure we could bore many people at a dinner party. (To which my wife just nodded her head!)

Having thought some more about this, I think in essence we are doing the same things but that we just think of it in different ways. This is probably down to the type of person we are and the way we think of things, in the same way that for some students they think of turning a sea kayak by edging to the opposite side and for others it works by lifting the knee on the side you want to turn to. (Same move just explained differently).

horis karloff
Posts: 180
Joined: Sun Nov 23, 2008 9:47 pm
Location: on crutches/mobility scooter

Re: Edging - how does it work etc

Post by horis karloff » Sun Nov 28, 2010 11:23 am

Only kayaks I edge are K1s when racing. In my sea kayaks I use the rudder, much easier!

User avatar
Kim Bull
Posts: 113
Joined: Mon Dec 21, 2009 12:39 pm
Location: Northumberland
Contact:

Re: Edging - how does it work etc

Post by Kim Bull » Mon Nov 29, 2010 2:36 pm

Mike Mayberry wrote:
It is a shame we are opposite ends of the country. I grew up in East Anglia and found when I moved here 15 years ago that there were many different ideas here to those I can been shown whilst learning. It was a great time, sharing and learning new methods. I'm sure we could bore many people at a dinner party. (To which my wife just nodded her head!)

Having thought some more about this, I think in essence we are doing the same things but that we just think of it in different ways. This is probably down to the type of person we are and the way we think of things, in the same way that for some students they think of turning a sea kayak by edging to the opposite side and for others it works by lifting the knee on the side you want to turn to. (Same move just explained differently).
Hi Mike,
Thanks for the time and thought you've put into this. I find it fascinating how peoples perceptions of what we do and how things work vary so much. I do think that generally when coaches get together and discuss such topics a number of limiting beliefs pop up, and realise it is very difficult to tease these out in a forum! It's good to see someone seeking out new ideas and methods.

If ever you're in Northumberland....

Very best regards,
Kim
www.kimbull.co.uk
Excellence in Canoe and Kayak Coaching

ian.miller
Posts: 94
Joined: Wed Oct 26, 2005 1:47 pm

Re: Edging - how does it work etc

Post by ian.miller » Mon Nov 29, 2010 4:06 pm

Goodness me I've never realised that it's all so complicated. Somewhere along the way my wee brain picked up the idea that the reason a boat turned away from the leaned side was due to the asymmetry of the leaning bow. In normal paddling your boat is actualy swinging very slightly from side to side and if you paddled on one side only you would turn in the opposite direction.
Edge the boat, sit upright and paddle normally and the edged bow presents more resistance to the water which results in a biased direction because the lower side of the bow resists any turning action while the turning action in the other direction is enhanced by less bow resistance and possibly by the increased rocker of the leaned boat. Another way to look at it would be to equate the leaned bow to a form of rudder.
In defence of this theory I find teaching it to sea paddlers is a doddle as it generaly works the way you explain it. There are the occasional beginners who manage to do it all the wrong way but they get there in the end. It is sometimes all about weight distribution and getting the upright body position on the edge.However teaching in a pool in boats with fairly rounded bows there is no obvious change to the symmetry of the bow when you edge so the effect is never convincing.
How far you lean is usualy a matter of confidence but I often persuade absolute beginners to initiate the edge by simply (if space permits) placing one foot over on top of the other.Not good for control but it does give a small controlled angle of lean and is usualy good enough to allow develoment of the skill.
I teach it as a method of maintaining or changing the boat's direction without using too much energy or slowing the boat down. Very handy when you are paddling close together since it avoids paddle clashes if you opt for a wide sweep.
It is also good on unskegged boats as a means of balancing against winds but it can mean you feel a bit exposed leaning continuously into the waves. In that case you can simply edge only on the windward paddle stroke. Not so effective but it certainly feels safer.
You could always fit a rudder and ignore edging all together!!

User avatar
Mike Mayberry
Posts: 804
Joined: Thu Nov 01, 2007 5:13 pm
Location: Pembrokeshire
Contact:

Re: Edging - how does it work etc

Post by Mike Mayberry » Mon Nov 29, 2010 7:30 pm

Kim Bull wrote:Thanks for the time and thought you've put into this........ If ever you're in Northumberland....
No problem, I may find that with some people it will be useful for them to remember which way to rotate if they start at the feet. It's another tool to explore further. I may pass your way one day soon on the way to Scotland. And of course if you ever fancy some paddling in Britains ONLY Coastal National Park...

Regards,

Mike

Chris Bolton
Posts: 2259
Joined: Sun Aug 22, 2004 11:33 pm
Location: NW England

Re: Edging - how does it work etc

Post by Chris Bolton » Mon Nov 29, 2010 8:18 pm

It's interesting how many different ways there are to visualise the same thing. One way I think of edgeing is that if you edge right, the vertical line of the bow goes right at the top, and left at the bottom. The stern does the same. The middle just rotates and stays on the same line. So in the water, the ends effectively go left, and the immersed shape is curved.

The best way to appreciate edging is to paddle a downriver racing C1. The boat is fairly tippy, and you only have a paddle on one side. So the boat turns away from the paddling side. To keep it straight, you edge the other way. You must edge, never lean - you don't have a paddle on that side!

Chris

User avatar
Adrian Cooper
Posts: 9510
Joined: Thu Apr 25, 2002 2:26 pm
Location: Buckinghamshire

Re: Edging - how does it work etc

Post by Adrian Cooper » Tue Nov 30, 2010 1:14 pm

I am very interested in the exchange between Mike and KIm. Like Kim, I have difficulty understanding the physics behind Mike's idea since, whilst one may turn one's torso, there is little other than air pressure to provide resistance against which to turn the boat. So it must be something else.

Indeed I use a similar technique coaching eddy turns. When you turn your torso to the direction of the turn, this tightens up the other side of your body and the boat almost automatically tilts into the turn. When coaching novices in eddy turns I advise them to turn their torso to point downstream, the ultimate intended destination and it helps prevent them catching an edge. It's a trick and it helps, it's not an excuse for better boat tilting technique.

User avatar
Mike Mayberry
Posts: 804
Joined: Thu Nov 01, 2007 5:13 pm
Location: Pembrokeshire
Contact:

Re: Edging - how does it work etc

Post by Mike Mayberry » Tue Nov 30, 2010 2:00 pm

Adrian Cooper wrote:I am very interested in the exchange between Mike and KIm. Like Kim, I have difficulty understanding the physics behind Mike's idea since, whilst one may turn one's torso, there is little other than air pressure to provide resistance against which to turn the boat. So it must be something else.
Equally, I have difficulty undersanding how you guys can't feel your hips/ legs wanting to point the same direction as you rotate your body to. I'm intrigued by all this too Adrian.
Adrian Cooper wrote:When you turn your torso to the direction of the turn, this tightens up the other side of your body and the boat almost automatically tilts into the turn.It's a trick and it helps, it's not an excuse for better boat tilting technique.
Indeed, it's another skill, seperate to edging, although it can help lead into it when coaching as you have described. I use the same thing in a moving water environment. In a sea kayak I am often edging one way but rotating the other way, using both skills to make a turn.

In my first reply to the OP I said
This assumes my body facing forwards, particularly the upper torso as....

When rotating the upper body in one direction the legs want to turn and point the same way.
and myself and Kim seemed to go off on a tangent, apologies to David. As this topic has developed there have been some interesting ideas coming out. I have sent the link to this out to a few of my regular customers as I thought it maybe of use to them. There's one in particular who is really enjoying reading and following it. It's "right up his street" to be fair, he's a chap who always wants to know exactly what each part of the body is doing throughout a move, right down to the little toe!

Mikers
Posts: 187
Joined: Tue Nov 30, 2010 3:00 pm

Re: Edging - how does it work etc

Post by Mikers » Tue Nov 30, 2010 3:25 pm

TechnoEngineer wrote:There are different types of hull - planing and displacement, and the amount of chine also has an impact.

Generally, whitewater boats tend towards having planing hulls with hard chines (especially surf kayaks) so they "carve" turn towards the side that's submerged.

Generally, sea kayaks have displacement hulls, which turn away from the side that's submerged, due to the different lengths of hull in the water. You certainly don't want the keel to surface, typically you can heel it by around 30 degrees before you fall in (if the Sea Kayaker stability reviews are to be believed).
Hello stranger - last time we spoke, you were a definite newbie. Learning fast as usual I see.
Coming back for Christmas? Fancy a curry? Are you still paddling those god awful sit on things?

Ian_Montrose
Posts: 281
Joined: Tue Jun 17, 2008 9:16 am
Location: Montrose, East Scotland

Re: Edging - how does it work etc

Post by Ian_Montrose » Tue Nov 30, 2010 3:37 pm

Adrian Cooper wrote:I am very interested in the exchange between Mike and KIm. Like Kim, I have difficulty understanding the physics behind Mike's idea since, whilst one may turn one's torso, there is little other than air pressure to provide resistance against which to turn the boat. So it must be something else.
The paddle blades whilst they're in the water, maybe? (That's not meant to sound facetious BTW). I use torso rotation routinely to execute/assist with a turn. I can't remember who taught me about it but I was led to believe it's an accepted technique. It certainly works for me, either on its own or in combination with edging, sweeping etc.

Mikers
Posts: 187
Joined: Tue Nov 30, 2010 3:00 pm

Re: Edging - how does it work etc

Post by Mikers » Tue Nov 30, 2010 4:22 pm

Ian_Montrose wrote:
Adrian Cooper wrote:I am very interested in the exchange between Mike and KIm. Like Kim, I have difficulty understanding the physics behind Mike's idea since, whilst one may turn one's torso, there is little other than air pressure to provide resistance against which to turn the boat. So it must be something else.
The paddle blades whilst they're in the water, maybe? (That's not meant to sound facetious BTW). I use torso rotation routinely to execute/assist with a turn. I can't remember who taught me about it but I was led to believe it's an accepted technique. It certainly works for me, either on its own or in combination with edging, sweeping etc.
I teach torso rotation to assist with turns for a very simple reason, the trunk is stronger than the arms. By rotating your torso during a sweep stroke, you reduce the amount of work that the arms and shoulders have to do - it lessens fatigue and simultaneously allows more control and aggression. :) A bit of edging at the same time can lift the ends out of the water, increase rocker and assist the turn.

Surely that's not what people are talking about here?

As for why the boat turns when edged, I've no idea - probably a combination of C of G and asymetry of the submergerd hull. It works though.

User avatar
TechnoEngineer
Posts: 3292
Joined: Mon May 12, 2008 7:47 pm
Location: Berks, Hants, Essex

Re: Edging - how does it work etc

Post by TechnoEngineer » Tue Nov 30, 2010 4:25 pm

Mikers wrote:Hello stranger - last time we spoke, you were a definite newbie. Learning fast as usual I see.
Coming back for Christmas? Fancy a curry? Are you still paddling those god awful sit on things?
Get your ass on Facebook dude! Yes I still paddle my SOT from time to time - usually when supporting river swims so I can relax on my foam armchair ;)
XL-Burn-3 / Monstar / Kodiak / My Videos

Post Reply