Timing is Important. Or is it?

Caterpillar Timing provided by SchoolandCollegeListings,com

One of the first things I learned as a dragon boater is that good timing is important. I have had many conversations with fellow dragon boaters on whether paddling in time is better or worse than everyone paddling out of time (sometimes called “the caterpillar”)

Timing is Important. Or is it?
Figure 1: Synchronised Paddling provided by International Canoe Association

I used to wonder if it really mattered that much. It turns out, it does, and there are some pretty clear reasons why.

You’ve probably seen dragon boats surging during strokes, wobbling and bouncing. This can happen when paddlers aren’t paddling together. But it’s not just about being in sync; it’s also about how you paddle. If your strokes are off – maybe your body moves too much – the boat can start pitching.

For this discussion, let’s assume we have two well-matched paddlers with good technique. We’ll focus on how paddling together affects the force that moves the boat. Extending the lessons highlighted here to a full dragon boat is valid. Using two paddlers just makes the imagery and calculations clearer.

When you paddle, the power face of the paddle blade pushes against the water, making the boat move. It’s like Newton’s Third Law: for every action, there’s an equal and opposite reaction. The force on the blade starts at zero just before you drop in for the catch at the start of a stroke, grows during the power phase, and goes back to zero during the recovery. If you’ve ever used a paddle ergometer, you might be familiar with a graph showing a paddle force curve over time.

Now, let’s simplify things. Imagine a basic graph of paddle force over time, where the force is either on or off, like a switch. We’ll call this the simplified paddle force profile.

Timing is Important. Or is it?
Figure 2: Simplified Force Curve

Now, picture two dragon boating scenarios.

  1. In the first, both paddlers are perfectly in sync.
  2. In the second, they’re “perfectly” out of sync, taking turns with their strokes.

    We want to figure out which scenario makes the boat go faster – which one produces the most force.
    When paddlers are perfectly in sync, the paddle forces are combined looks like a switch turning on and off (see green line in Figure 3).
    Note Paddler One’s force curve is hidden behind Paddler Two’s because they are perfectly in sync.
Timing is Important. Or is it?
Figure 3: Two Paddlers In Sync

But if they’re perfectly out of sync (Combined force in green in Figure 4), the resultant force is constant because one paddler is always pushing when the other isn’t.

The question is, which scenario makes the boat go faster?

Timing is Important. Or is it?
Figure 4: Two Paddlers Out of Sync

Figure 5 is an animation of two paddlers who start off 100% out of sync and slowly come into sync. As you can see the shape of the resultant force (in green) changes.

The resultant force when totally out of sync is constant, however as they come into sync the resultant force peaks at higher values but drops to zero at other stages.

Timing is Important. Or is it?
Figure 5: Two Paddlers Slowly Becoming Synchronised and the Resulting Force Curve

Interestingly, the average force is the same – paddling in sync or out of sync makes no difference to the average force applied by the paddlers.

So are we saying it doesn’t matter if paddlers are in sync or not?
Short answer, No!
Why? To answer this, we’ll consider the speed in each scenario.

Let’s make it simple: assume the boat is already moving at a good constant speed, and we’ll focus on the forces that move it forward.

With some physics equations, we can relate the total paddling force to the drag force (the force of the water slowing the boat down).

When the two paddlers are 100% out of sync, the force remains constant. That mean no acceleration. So that part of the formula becomes zero and the total paddling force is equal to the drag force.

When the two paddlers are in sync there are 3 phases during a stroke:

Firstly, during the drive when we have acceleration

Secondly, a point where the paddle forces equal the drag forces. i.e. no more acceleration.

Finally, when the paddle is in the air on return. i.e. the drag forces slow the boat down.

What is the drag force (FD)? We have covered the formula for drag in a previous post (“Can 20 paddlers make a dragon boat 20 times faster than one?“) so I won’t rehash it here.

Suffice to say that as long as the boat is moving, the drag forces are trying to slow it down.

OK. Enough of the physics. Let’s put this into a graph.

Figure 6 shows the constant velocity of the out-of-sync paddlers (no acceleration so the paddle forces equal the drag forces) and also the velocity of the in-sync paddlers (3 phases)

For the in-sync paddlers (see Figure 6), during the power phase of a stroke (green), the boat speeds up, and during the recovery (blue), it slows down due to drag. In a steady state (yellow), when there’s no acceleration or deceleration, the boat’s drag force and paddle force are in balance.

Timing is Important. Or is it?
Figure 6: In sync paddlers speed up and slow down but never slow down enough to get down to the speed of individual paddlers out of sync

For perfectly in-sync paddlers, the speed stays nearly constant, while for perfectly out-of-sync paddlers, the speed is always constant because the force is constant.

In our examples, the in-sync paddlers reach a higher speed during the power phase compared to the out-of-sync paddlers because they are producing more combined forces. (compare Figures 3 and 4)

“Timing is important. Even though the in-sync paddlers slow down during recovery, they never dip below the steady state speed of the out-of-sync paddlers.”

The greater combined force of the in-sync paddlers wins.

These examples are a slight exaggeration to help understand the physics that is going on.

So, while drag does slow the boat down while the in-sync paddles are in the air, it doesn’t get enough time to slow the boat all the way down to the constant speed that out-of-sync paddlers have.

HOWEVER, if you gave drag enough time (i.e. a long time in the air on your return) then the speed would drop down to at or below that of the of the out-of-sync paddlers. But we don’t do that – do we?

Another scenario where in-sync and out-of-sync paddlers would travel at a similar speed would be if the drag forces are so large that the boat slows as soon as the in-sync paddles are in the air (think paddling through thick mud).

The best solution is to paddle perfectly in sync – it makes the boat go faster by maximizing the combined force to overcome drag forces.

“Timing is important. To go faster, paddle in sync and don’t coast too long between strokes”

Cover photo provided by Caterpillar Timing provided by SchoolandCollegeListings,com


Please enter your comment!
Please enter your name here

This site uses Akismet to reduce spam. Learn how your comment data is processed.