The Straight-shaft Paddle
It's been around since the dawn of canoe time and the straight shaft canoe paddle isn't ever going to leave. There's nothing wrong with straight shaft paddles but there's nothing wrong with improving either.

Because the straight shaft paddle does not clear the body of a paddler like a bent shaft paddle does, the paddle-swinging dynamics change. The paddle gets lifted higher into the air before it's dunked in the water. Then, as it is pulled through the water by the blue arm, the green arm ends up actually pushing forward. This makes the blue arm point of contact act like a fulcrum or the "pivot point on a see-saw". As the paddle is being pulled through the water, the shoulders of the paddler drop with is and pull it through the water. The result in this stroke is that in the Total Stroke length, only about 1/3 or 33% of the entire stroke is "push". Starting at stroke-point "E" above, the paddle is not pushing water back but instead lifting water. Instead of effectively pushing the canoe forward, the lifting force of the paddle is actually pushing the paddler's butt (and the canoe) down into the water.

But, this paddle does a J-stroke beautifully. Just by dropping the shoulders at the end of the stroke and rotating the shaft downward by the top of the paddle (thumb on the hand of the green arm turns down thereby standing the following-through paddle blade into a rudder at the back of the canoe). The end result is that a straight-shaft paddle is more about steering than about push.