Oh sure, put me on the spot.

Worthy goals for any kayak paddle: efficiency, predictability, comfort.

Paddles work primarily in a drag mode like a parachute. They move primarily parallel to the direction of motion of the kayak. There is a small component of wing like action (lift produced by motion perpendicular to the direction of travel) as they dip in or out of the water.

Drag is optimized by surface area and distance the water has to travel to get around the blade. For a given surface area a circular face will produce the most drag.

While wing like lift is less important, it is optimized by having thickness to the paddle. Idealling the thickness would be concentrated towards the leading edge of the paddle, but for most strokes this isn't practicle since the leading changes as the paddle enters and exits the water. Modern wing paddles get around this with a vertical paddle plant followed by a lateral motion out to the side which keeps the top edge of the blade the leading edge through out the stroke. But they are only intended be good for straight ahead paddling. The technique is a little awkward but can be used with any paddle.

Thickness in the middle of the blade will give fairly efficient lift during the forward stroke. It also makes the paddle more predictable in sweeping/slicing strokes such as sculling. People often fail on rolls for two reasons: they hold the paddle at too steep an angle and the paddle fails to give the expected lift, or the hold it at too shallow an angle and it slices deep.

The first problem is caused by the paddle stalling while acting like a wing so it doesn't provide good lift. The tendancy to stall is reduced by making the blade thicker. The relatively thick shape of traditional paddles is very stall resistant. While a wider blade would need to be very thick to be as stall resistant, just a little thickness greatly reduces the tendancy to stall.

The tendency to slice deep can be reduced by putting the center of effort of the blade above the axis of the paddle. This can be acheived by arcing the blade along its length so the middle of the blade is behind the center of the shaft. This kind of blade can be sculled with a loose grip. It will predictably self-feather as you change directions so it is always lifting.

Some paddles have curved shape across their width. These paddles tend to arc in the direction of their curvature making them require a tight grip to maintain lift while rolling or sculling. It is easy to mess up with this kind of spooning.

The speed the paddle moves against the water and how much strength it takes to move the paddle is related to length. Longer will move through the water faster and require more strength to move. Moving the blade closer in on a short shaft effects the strength needed without changing the efficiency of the blade itself A shorter shaft will also make the mechanics of getting the blade in and out of the water easier. While longer paddles will help you go faster they tend to loose efficiency due to a deep stroke and more difficult recovery.

You can keep a long paddle near the surface but only by having it far out to the side which makes the stroke less parallel to the direction of motion (it curves) and it forces the kayak to yaw.

Obviously, you can also make the paddle easier to pull if the blade is smaller, while this is acheived by reduce efficiency, you will reduce it less by making the blade shorter than by making it narrower.

You want to be able to get the blade fully submerged before applying power to prevent it from ventilating (sucking air down the blade) so the length of the shaft can be determined by how the shortest length you can comfortable get into the water. This will minimize the strain on the body. The blade can then be relatively short and wide to provide an efficient grip on the water.

Most people will probably be more comfortable with a slightly bigger shaft than typical. What is typically most comfortable is the size made between the thumb and forefinger on a relaxed hand. An egg shape with the widest point against the palm is more comfortable than perfectly round and provides a reference for rolling.

Because the whole paddle is relatively small it can be lightweight.

: What are the elements of a good modern paddle, in your estimation?

: Give us a list of desireable characteristics. Even though this is one of
: those topics that seem to stir up partisan passions, I am sure everyone
: will moderate their responses in the spirit of the season. (in other
: words, I'm not trying to get you in trouble, just curious for your views)