I was reading this: “http://www.stcharlescanoeclub.com/which_boat.pdf” mostly out of curiosity.
They mention a couple of times about how boats must be “popped in the shallows”.
What is this and how does one do it? Is it at all applicable to standard recreational canoes, or just to the race-specific boats?
Thanks.
popping
Paddling hard in shallow water feels like you’re paddling uphill because of the large bow wave that’s created at the front of the boat from the energy reflecting back from the bottom of the river/lake.
If you can sprint hard going into shallows, before this bow wave is created, you can get enough speed built up to jump ahead of this wave so that it comes up farther to the back of the boat, letting you ride your own wake so to speak. If you get stuck behind the wave it’s extremely hard to paddle over it.
This isn’t easy to attain or maintain but it can be done, easier in some boats than others. I think you’d be hard pressed to get it done in a boat that wasn’t designed to go fast. The shallower the water the better it works. Once you’re in water over a couple feet deep I don’t think you’re going to do much popping and you just have to deal with the suck water.
Alan
Thanks!
That was fast! I suppose you racers type quick too.
That makes sense, and is an interesting way around (over) the problem.
So would it be possible to use this technique with a fast rec boat like a MinnII or a Jensen 17?
Popping a Jensen
Both boats you mentioned will pop. The trick is to know that the very shallow water is coming and then paddle hard enough to lift the hull onto the pressure wave rebounding off the shallow bottom. An empty Minnesota II is so close to a race hull it behaves like one. The 17’ Jensen is much harder crank up to the necessary speed.
The Baldpaddler has done it on a good day being chased by the devil.
Bill
On plane?
This sounds like you’re putting your hulls into the planing regime - a flat fore-hull would help this. I guess that’s why you hear about it in canoes, but not kayaks.
No planing
It’s not planing, just riding a wave. Works with kayaks too.
Alan
It is simple.
– Last Updated: Nov-10-10 2:00 PM EST –
It is surfing your own wake basically.
As you come into the shallows ("suck water") the low water puts your brakes on, and as soon as the front bow wake catches up to you, you give a super hard paddle, and sort of bounce up on it, and then just keep doing it.
Recently we did two different river races that were very low, and used it on many of the sand bars that we crossed.
On one of them we had been neck and neck with two other canoes and were behind them both. Neither of them knew how to do it, and we came off that particular bar in front of them.
The first one we were in our Jensen 17, and the second in our comp cruiser
jack L
Got it - surfing the bow wave - cool
yeah my version
my version in describing.
When you paddle there is a bow wake (small wave) flowing-moving forward with the boat in the same direction and outward.
This was is HIGHER than the surrounding water…just look next time you paddle.
In shallow water…and we’re talking shallow…under a foot lets say as as little as 5 inches deeps…that wave/wake i mentioned above basically takes up all the water in that shallow depth.
If you paddle fast…i.e sprint…the canoe will NOW for a moment (maybe 3-20 seconds) with actually be going faster than that wake i mentioned above. SO if it is NOW going fast it ALSO “popped” up ONTOP of that wake and is being pulled along by the wake…ie. the forward motion of the wave is “surfing” your canoe sort of…thus the canoe is higher out of the water…making it NOT hot bottom in the shallows, AND is being pulled along-forward by the wake…
This only last a short time as mentioned above…since most cannot maintain the 80-100 stroke rate per minute to keep it up for long periods AND the shallow part will most likely end and become deep again so its no longer neeeded.
It is beautiful
when you can pop it and keep it going. Takes practice and stamina. I once saw Tim Jones pass us like we were standing still. We were in 2-3 feet and Tim was as close to shore as he could get. Dang guy made his solo fly.
I remember about five or six years ago
paddling with you on Mtn Island lake, and you wanted to practice “popping the shallows”
I thought you were nuts !
I just wanted speed in deep water.
I still do, but that kind of practice is good every now and then.
Jack L
Popping myths
Explain again how you can surf a wave that hasn’t yet been created?
Popping the hull exists, no doubt. John Winters discusses what occurs, a matter of wave theory and drag changes.
Don’t doubt
I don’t doubt you’re right in that we’re all wrong in our explanations, I’m certainly no expert and am just repeating what I’ve heard and how I explain it to myself.
The one thing that always bothered me about the explanation of jumping ahead of the wave is that if that was the case shouldn’t it be easier to do in deeper (2-4’) water since it should take longer for that energy to reflect off the bottom and harder to do in very shallow water? Instead it’s the opposite.
Alan
It doesn’t work for you since…
you are so damn fast that your bow wake never catches up to you as you plane over a few inches of water.
It only works for us slow pokes !
jack L
Surfing the bow wave, I think
I know that waves in shallow water have a speed limit based on depth (actually square root of depth). This is why waves crash at the beach - as a wave train progresses towards shore, the ones nearer to the beach slow down due to decreasing depth. The waves behind are still moving quickly, so catch up and overtake the nearer wave. This process of waves catching up to the ones in front leads to a buildup of water and the wave becomes taller until it breaks.
If you’re paddling in shallow water, you are creating a bow wave at the speed of the boat. If the water is shallow enough, the boat speed may exceed the wave speed, so the bow wave, once it’s been created must slow down. If you can manage to maintain boat speed, that means you can overtake your own bow wave and surf on it. I think this may be what is happening during ‘popping’.
wave
it is a wonderful thing!!! will let ya pass another boat in very shallow water. it also is something you must feel like a side wake
check out the governing equations
Suck water starts at 1/2 the waterline length of a displacement hull. That is the wavelength at which a surface gravity wave starts to “feel” bottom. It gets progressively worse until you hit “pop” water.
“Popped” water happens when you can push your speed to the speed that would generate a wave that would “break” in the depth of the water in which you’re paddling.
Check out the governing equations for waves in an oceanography text. The speed and depth at which lightweight paddle craft “pop” is pretty close to the speed and wavelength at which a surface gravity wave would break in shallow water. Waves tend to break or topple when depth is 1/10th of the wave length. That would be about 21" for an 18’ boat being held at hull speed. Of course, with a boat you’ve got to sustain that speed. And you’ve got to overcome the wave you’re already pushing as it starts to interact with the bottom. And if you’re right on the border of popped/not popped you might end up shoving a shallow water wave ahead of yourself which is going to create crazy amounts of resistance. If you’re in 3-4’ of water you’d have to go at the hull speed of a 30’ or 40’ boat to pop. That is why we call that water “suck water”. I know that in my k1 that if I’m exceeding a speed that correlates to a wave of length(X) that breaks in depth(D) I’m popped. If I’m paddling near hullspeed in 3’ of water? I’m slammed up behind a wall of shallow water wave.
When you pop the boat you may not be literally “surfing” your own wave. You may actually be forcing the hull into a speed range where it is behaving more like the “foamy” of a broken wave (anybody that surfs knows how fast the foam pile moves relative to the water underneath). It is a lot like planing. The shape of the wash (at least in my k1) is V-shaped much like the wake off of a boat on plane. The wake off the boat is definitely shaped differently than the wake off of a boat running at displacement speeds in deep water.
To further confound things, the shape of the hull and trim make a tremendous difference. You’ve got to be able to force the water under the hull so that you skim forward.
Sounds like we agree
– Last Updated: Nov-13-10 10:14 AM EST –
You have a much richer vocabulary for the phenomenon, but it sounds like we agree on the mechanism. The one thing I would change is the statement that a wave will break at a specific depth, say 1/10 of its wavelength. Breaking requires a slope in the bottom topography - the depth gradient causes the sequential change in the speed of translation of the wave train that leads to breaking.
PS Now that I've thought about it, maybe you mean, when a wave from deeper water ~enters~ a channel that is 1/10 its wavelength, it will break. That sounds exactly right.
Winters’ thoughts
Was just poking around the interwebs tonight and found a post from John Winters on the subject, you can see the thread here:
http://www.myccr.com/SectionForums/viewtopic.php?f=49&t=32683
I’m in no position to argue with him.
Alan
Thanks Alan, and Mr. Winters
I particularly like this part “This lacks the drama of boats leaping over their bow waves but it avoids the difficulty of having to explain how the boat travels down the front of a wave it has yet to create.”
It seems that often in science we confuse the model or the simplified explanation with the reality. Of course, “why” doesn’t really matter to the paddler as long as they know “what” to do. Interesting phenomenon, though, and it is great that I keep learning new things about canoes.