There are several considerations to keep in mind when selecting a touring paddle that is appropriate for your use.
Most touring kayakers do well with a 220 to 225cm paddle. But the right length varies with paddling style, boat width, and torso and arm length. The best way to determine what works best for you is to get out on the water with the paddle. If paddling with others, borrow paddles of different lengths to get a sense of the effect on your performance (allowing for any other differences, such as blade size).
You might choose a shorter paddle (210 to 215cm) if any of the following apply:
You may want a longer paddle (230 to 235cm) if:
Almost all touring kayak blades are asymmetrical blades, which are shaped differently above the paddle shaft than below it. This ensures that when the paddle enters the water at the intended angle, the submerged blade surface area is equal on both sides of the shaft. If the surface areas, both above and below the waterline, were not balanced, the blade would tend to twist and flutter as it was pulled through a stroke.
Asymmetrical blades range in shape from fat ovals to long thin quills; and in cross-sectional profile, from nearly flat to curled wings and dihedrals.
Like a longer shaft, a bigger blade area lets you apply more power, but also demands more effort on each stroke. Bigger blades are typically designed for paddling at more vertical angles. They appeal to those who want more immediate response from their paddle strokes.
Smaller blades don't transfer power as quickly, and need to be paddled at a higher stroke rate to achieve the same speed as a larger blade. But, they demand less effort per stroke. This may be easier on wrists and shoulders, especially when paddling a heavily loaded boat. Smaller blades are usually designed for use at near horizontal angles.
Straight shafts are less expensive, and stronger for a given weight than bent shafts. Some paddlers also find them more intuitive for angling the blade correctly during slap braces, sweeps, and blind rolls.
Bent shafts are crooked on each side to let your wrists work at more ergonomically friendly angles. Because of their more complex shape, bent shafts are more expensive, and either a bit weaker or a bit heavier than straight shafts, depending on how much material the manufacturer opts to use.
Strictly from a paddling performance point of view, one-piece paddles would be ideal. They're lighter and stronger, with no moving parts to go wrong. However, to facilitate storage, transport, and feathering, most touring paddles are made with ferrules.
Ferrules are the slip-together joints that hold a multi-piece paddle together. They range from the basic fishing rod type held in place with a pop-up button, to sophisticated joints. The more ferrules a paddle has, the smaller the it breaks down, and the easier it is to carry below decks, to pack, or to take when flying.
But ferrules add weight, and can fail in a couple of ways. They may "freeze" shut from accumulated salt water residue. Or, they may develop play caused by wear between their surfaces (which happens faster if salt residue is trapped inside a ferrule). The more loosely a ferrule fits in the first place, the more prone it is to developing wear and wiggle.
Feathering describes the angle of the two paddle blades relative to one another. Paddles with both blades parallel are unfeathered; those with offset blades are feathered. Feathered paddles reduce resistance from headwinds, but may be more likely to cause wrist problems if the paddle is gripped too tightly.
One-piece paddles are permanently unfeathered or feathered; paddles with a ferrule at the middle of the shaft can usually be assembled unfeathered or feathered. However, the degree of adjustability varies with the type of ferrule. Push-button ferrules may have only one preset angle of feather (typically between 60 and 75 degrees) or they may only adjust in increments of 15 degrees or so. Some ferrules can only be feathered for right hand control. (The control hand is the one that flexes when using a feathered paddle.)
The LokTite feathering system from Accent Paddles allows you to pick left or right feather in any 15 degree increment from 0-90 degrees; twist the ridged knob to dial it in, and from then on just pop the two shaft halves together with the press button.
Asymmetric grips are sections of the paddle shaft that are oval rather than round in cross section. This makes them more comfortable to hold and less prone to twisting. Asymmetric grips allow you to determine the blade angle without looking. Called "indexing", this feature is handy during blind manoeuvres such as rolls. Some paddles add an additional "grip index" to their shafts, offering greater certainty of your hand placement.
Drip rings prevent water from running down the shaft and along your hands and arms. Most paddles come with drip rings, but they are also available separately.