Nikki Gregg recently responded to a woman asking about choosing the best SUP. Here is what Nikki had to say...
Blade size/shape, shaft flexibility and length are ALL factors when deciding on a new paddle. In addition, you also need to determine exactly what you'll be using the paddle for MOST of the time in order to pick the right one for you. For example, you may want a shorter length paddle if you surf most of the time and a longer paddle if you are a distance paddler. If you switch back and forth between the two disciplines, maybe an adjustable will work best. So, here is my advice:
If a paddle is too long it's going to be hard on your shoulder joint, if too short it will cause you to bend over too much risking strain on your lower back.
A shaft that's too stiff can cause overuse injury/tendinitis and a shaft that's too flexible may take some power out of your stroke.
Also, a blade that is too big for you can be hard on your joints. Personally, I like a smaller blade because I have shoulder problems and, in general, I like to paddle at high RPMs when racing and catching waves in the surf.
If you're not sold on the smaller blade size, also consider the SHAPE of the blade. Werner makes a long, slender blade called the Nitro. Unlike a teardrop-shaped paddle which has a big bite during the catch phase, you can adjust how much power you get out of the stroke by how far you place the blade in the water. Full submersion for full power, half submersion for half the power.
Also make sure the paddle is the right length for you, meaning when you reach your arm up the paddle goes up to your palm so that your fingers can just reach over the top when you stand the paddle in front of you. I prefer to size the paddle by reaching my arm up and not by a certain amount of 'inches over your head' that some people recommend. Everyone has a different reach and different proportions (for example, some people have long ape arms ;) Also take into consideration, when sizing your paddle, the thickness of your board. If you have a very thick board that floats you high out of the water you may want to consider adding a couple of inches to the length of your paddle.
There are a lot of great paddles out there, but I am a Werner girl, so I am a little biased. I love their paddles. They have an ultra light paddle that just came out called the grand Prix that comes in three different blade sizes and the option to get it in a bent shaft. The benefit of the bent shaft is less strain on your joints and farther reach with each stroke, meaning you get further, faster). They Grand Prix may be a little more of an expense up front, but hey, I think the paddle is your most important investment in SUP because it's your connection to the water. It should be the best paddle you can afford and you'll probably have it longer than your board.