I've had some pretty toasty discussions regarding the proper paddle length for sea kayaks. Some suggest there is no reason to reach out beyond 220 cm, while others prefer the laid-back long stroke of a paddle at least 240 cm.
For a while the trend was to go with a very short (215 cm and less) paddle, using a vertical stroke similar to canoeing. Some still prefer to paddle this way as it provides speed and power in each purchase of the blade with water. To me, the obvious question becomes "For how long do you need to maintain quick speed and power in your stroke?"
A well-designed and well-trimmed sea kayak will usually maintain a straight course on the glide between proper paddling strokes. Once the boat is up to a modest touring speed, the inertia of the boat can be maintained with only casual, forward strokes that help maintain that glide with very little effort. An occasional power stroke might be called up for a quick maneuver but for distance paddling in calm weather, what's called the "touring" stroke is quite adequate.
Speaking of calm weather, length can play a role in how easy it is to paddle in higher winds or contrary seas. A longer paddle is going to be affected by the wind more than a short paddle. Rough seas can sometimes make a longer paddle cumbersome as well.
A longer paddle (220cm +) that enables the blade to enter the water at a rather acute angle (as opposed to nearly vertical) when accompanied by a casual pulling stroke is oftentimes all that is necessary to maintain an acceptable, pace-keeping forward motion. A short paddle usually won't reach out far enough to paddle in this relaxed, "touring" style. Conversely, a long paddle planted nearly horizontally in the water becomes cumbersome if too long.
Naturally the size of the paddler, arm and torso length, all affect the length one should choose. At 6' 7”, I can make a 240cm paddle look pretty short. Those who are concerned with their paddle's weight ("Let's see, that's 10,000 strokes at 2 pounds per stroke, that's like heftin' over ten TONS of weight, dude!") will want to consider a shorter paddle for the mere weight of material alone. Conversely, if weight is a factor but you prefer the length, go for the lightweight composite shafts and blades available in the marketplace.
Like other applications in kayaking, trial and error are your best bet to ascertain what paddle length is best for you. Besides your size, the size of the boat matters – or more precisely, the beam or width of the boat. Wider boats such as tandems often require a slightly longer paddle shaft than you'd use to paddle solo.
A trend in paddling that is becoming popular again is the use of a double-bladed "kayak" paddle when solo canoeing. A longer, two-bladed paddle tends to offer the needed length to both reach out and down to the water from the higher center seat. Those who tend to kneel while paddling will tend to use a slightly shorter kayak paddle.
Basically it comes down to personal preference with emphasis on a casual, broader cruising stroke or a more upright, right-angled power stroke as a key factor in selecting your preferred paddle length. I've noticed, too, that those who use a longer paddle tend to have their hands a bit far apart on the shaft, some to the point that it becomes extremely inefficient to paddle that way.
I also have a theory that if a beginner starts out with too long a paddle, he or she often fails to develop a good rotating torso technique. The shorter paddle, to be placed properly, tends to encourage the paddler to rotate. The longer shafts, however, make it easier to simply reach out and pull the paddle back using only the arms, with no rotation at all. Again, the prudent option, for anyone not sure of which length is best, is to experiment with several paddle lengths until you find one that is comfortable yet promotes proper paddling technique.
From a historic perspective, paddle length seems arbitrary. For many coastal cultures, materials were limited, sometimes making it virtually impossible to find a single piece of wood long enough to serve as a double paddle. In many regions, it was far more typical to see kayakers paddling with a single bladed paddle, not two.
Paddle length, therefore, is a judgment call based partially on style of paddling, type of boat and skill level. Longer paddles work well for a relaxed, cruising strokes. Shorter paddles may offer more control and be more effective in delivering a power stroke. Paddles come in even increments of 10 cm. which means a 220 cm paddle is about 4” shorter than a 230 cm. paddle. That's only 2” in length on each side. It doesn't seem like much but there can be a noticeable difference in the stroke.
Learn proper paddling skills first before experimenting with different lengths. Personally I have a couple of lengths I use regularly. Naturally I choose the longer shafts for doubles and canoes as mentioned, but also for lazy, relaxed paddling or fishing. I carry a shorter paddle on my deck for a spare and for occasions where I want really need or want to make steady vertical power strokes.
Tom Watson is an avid sea kayaker with 15 years experience in the North Pacific waters of Kodiak Island, Alaska. He is also a freelance writer whose articles have appeared in most of the popular kayaking publications. He is a frequent presenter at regional kayak symposia. His third guidebook entitled "How to Think Like A Survivor" was released in Spring 2005.