rudder placement

Anyone know what kind of effect it would have if the rudder were moved way forward, like just behind the seat? Could it keep the rudder in the water on a wave to still have control but maybe allow for a smaller rudder therefore reducing drag? Just a thought.

Submitted by jpi92109 on Mon, 03/03/2008 - 11:43pm



Hi Jp in pacific beach,

Hmm. maybe you could tell us what you think might happen if sucha thing were to be done.


#1 Tue, 03/04/2008 - 3:53am


Id like to see what a canoe would handle like with the rudder mounted up near the bow. Id be willing to bet a designer could use a much smaller rudder and still retain excellent steering control with even a steeply raked back rudder.


#2 Tue, 03/04/2008 - 4:16am


Hi Onno

Thats why im inquiring but it seems like even with the tail being lifted out of the water by a wave, if the rudder were a couple feet farther forward, it would still be submerged, therefore still giving steering control? But because of this, maybe we could even use a smaller rudder resulting in less drag? Something like a carbon material;super strong and thinner than a normal rudder? These are all just random thoughts but there seem to be alot of inquiries like this on here so i thought id give it a try.

jpi92109 is just an old email sign on. im actually in Kona now. I forgot there was anywhere else on earth!


#3 Tue, 03/04/2008 - 4:53am


My guess is that the closer you move the rudder to the center of the boat, the slower the canoe will turn. Once the location of the rudder is at the point of rotation or at the center of the canoe, the canoe will not turn at all. Torque is defined as: The measure of the force applied to produce rotational motion. It is usually measured in foot-pounds. Torque is determined by multiplying the applied force by the distance from the pivot point to the point where the force is applied. If you think of the rudder as the point at where the force is applied and the same force is applied to the rudder at different positions, the amount of torque decreases as you move the rudder toward the pivot point (i.e., the paddler).

Snarf, Ph.D in Brokanics, Pseudo Sciences and Nocturnal Paranormal Activity


#4 Tue, 03/04/2008 - 8:20am


Recently I tried to find a good answer to that question. Not much out there.

A bow rudder has problems in following seas, they say.

Prof Snarf is right, your momentum is less when you move the rudder forward because the lever is shorter. You can increase the size of the rudder trying to compensate for that if needed:
The increased blade would render a larger force, and force x lever would give you the same momentum or torque.
So, no, the rudder would not be smaller.

I don't see why the turning should be slower, but who knows.

On the other hand, you will need a smaller angle of attack when your rudder is closer to the center of the boat.

I moved the rudder on a Hurricane and I find that you have to re-learn how to steer the boat. No clue if it is better or not, the rudder is not in perfect shape.

When your rudder has any type of surface damage/scratches, it will stall much earlier. Iow, your rudder needs to be in excellent shape, too.

If you make your rudder too thin, it will have reduced lift and will not work correctly. A rudder is ideally shaped like a wing. Blade rudders without profile exist, but they are not ideal, certainly not for surfing.


#5 Tue, 03/04/2008 - 12:58pm


The next time you go paddling in a 6 man canoe, have # 3 steer the canoe instead of # 6. Let us know how that works.


#6 Tue, 03/04/2008 - 2:36pm


shot in the dark
in my younger days we would play and turn each other from the stern and the closer to the back the better. I would think the farther back the better for a rudder.


#7 Tue, 03/04/2008 - 2:38pm


Not only by moving rudder forward will you make it slower to turn you'll also be adding a huge amount of drag because you'll be on the pedal longer (and deeper).

For the least amount of drag you want rudder far back where tiny rudder corrections adequately turn the boat without increasing drag too severely. However, too far back and it's useless in the bump.

As far as mounting under the bow, I dunno the physics so I'll just hide behind "nowhere in naval architecture do I see bow-mounted rudders in fast, maneuverable boats (with nothing mounted in rear)." Yes I know, a weak statement....Cheers.


#8 Tue, 03/04/2008 - 5:34pm


Back in the early '90s a paddling mate of mine Fleety put an extra bow mounted rudder on an OC1 that he had made out of a surfski. This surfski with Ama and 2 rudder setup (Bow and Stern) flogged every other OC1 around in those days in the bumps. When he tried to enter the official AOCRA races they banned him. Not so much for the extra rudder, but for the fact it was essentially a surfski with Ama.

Modern Oc1's are now pretty much just that, surfski with Ama. We sure took the long way to evolve didn't we.

Getting back to the bow rudder, it worked, it was smaller than the stern rudder, but for some reason that i still don't know, it created a lot of drag.

This canoe was actually mentioned in one of the early KanuCulture books.

Mr Fleety, you were well before your time.

If you wanna see some skills with a canoe paddle no rudder, watch this video right through. It's awesome.
Don't be fooled by the start, appreciate this for what it is.
Best is towards the end, worth the download.

Cheers Rambo


#9 Tue, 03/04/2008 - 6:08pm


It would have to be seat four with a huge blade. Yes we can. :)

If you are closer to the axis of rotation you would need a smaller angle of attack for the same effect. More drag overall ?
I talked to some boatbuilders, they had different opinions. It depends what effect you expect from your rudder.

I am not a boat builder; I am trying to think through here what I remember from physics/fluid mechanics.


#10 Tue, 03/04/2008 - 10:53pm


The rudders and rudder positioning offer a large amount of posible optimisation ,remember rudders depending on size present a relatively large source of drag 2+-% of an OC1 while keping in mind that most modern Oc-1 differ in drag in range of 1% ,Flat water sprint boats on the other hand only cca 1/10 %

Forvard rudder should have worked just the same or beter than the rear rudder but in the end the diferences can mostly be achieved by making the rudders smaller ,but here you are allways treading a thin line of how small is enough,technicaly the boats can be without rudders at all would be the fastest,but the paddlers are used to steering with a rudder.

This videoshovs is the ultimate in canoe control and paddling precision WW slalom C-1


#11 Wed, 03/05/2008 - 11:41am


rambo,
that video is cool.....
mahalo.


#12 Wed, 03/05/2008 - 12:45pm


Hey Canoemaker
Thats gnarly. Isnt that what Karel senior used to do?


#13 Wed, 03/05/2008 - 3:12pm


Wow. Thanks, Rambo; you just took me back to childhood spending my summers paddling Canandian northwoods in wood/canvas canoes playing around with the same techniques. I'm glad they mentioned the canadian-stroke; a truly awesome, efficient canoe-tripping stroke. Looks like the paddler's doing nothing but stroking but it's all in the feel and where you're putting torque. You're actually pulling up on the blade keeping it submerged as you recover while never touching the gunnels yet applying the same torque to keep canoe straight.Takes a long time to master and become efficient but beats the hell out of the typical J-stroke where folks generally pull, then pry. Tilting canoe just shortens waterline to make it more meneuverable. You quickly learn (or not) that secondary stability is more important than primary.

Anyway, enough rant...thanks again for the trip down memory lane. So it sounds like I haven't a clue about rudder placement, eh? Not surprised.... Did that bow-mounted rudder really work as stated? Cool.


#14 Wed, 03/05/2008 - 7:28pm


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#15 Wed, 03/05/2008 - 8:24pm


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