m (→Materials and designs: add SI units)
Paddles commonly used in [[canoe]]s consist of a [[wood]]en, [[fibreglass]], [[Carbon fibre reinforced plastic|carbon fibre]] or [[metal]] rod (the ''shaft'') with a handle on one end and a rigid sheet (the ''blade'') on the other end. Paddles for use in [[kayak]]s are longer, with a blade on each end; they are handled from the middle of the shaft.
Kayak paddles having blades in the same [[Plane (geometry)|plane]] (when viewed down the shaft) are called "un-feathered." Paddles with blades in different planes (such as in the image) are called "feathered". Feathered paddles are measured by the degree of feather, such as 30, 45, or even 90 degrees. The paddle in the image to the right is feathered around 15 degrees. Many modern paddles are made of two pieces which can be snapped together in either feathered or unfeathered settings. The shaft is normally straight but in some cases a 'crank' is added with the aim of making the paddle more comfortable and reducing the strain on the wrist. Because the kayak paddle is not supported by the boat, paddles made of lighter materials are desired; it is not uncommon for a kayak paddle to be two pounds (32
Cheaper kayak paddles have an aluminium shaft while more expensive ones use a lighter [[fibreglass]] or [[carbon fibre]] shaft. Some paddles have a smaller diameter shaft for people with smaller hands. Paddle length varies with a longer paddle being better suited for stronger people, taller people, and people using the paddle in a wider kayak. Some paddle makers have an online paddle size calculator. Blades vary in size and shape. A blade with a larger surface area may be desirable for a strong person with good shoulder joints, but tiring for a weaker person or a person with less than perfect shoulder joints. Some paddle makers offer blades in three sizes.