Slight changes in dimensions and shapes will favor different performance characteristics,. A longer kayak tracks smoother and faster. In moving through the water, the hull must separate the water at the bow, allowing it to return to the stern as smoothly as possible. A shorter kayak results will be less streamlined through the water, but the hull will be more maneuverable. A longer kayak will have more stability and load carrying capacity.

Width is a key to a good fit. A wide kayak will be more stable than a narrow one. A narrow craft is usually faster than a wide one, but will compromise some stability. A wider kayak will provide more stability for both heavier paddlers and tall paddlers with a higher center of gravity. A wider kayak will allow a paddler to spread their legs out more. This is another key component of fit. A deeper hull will be roomier for paddlers with larger legs, and increases load carrying ability. It also improves secondary stability by having more volume to help support a paddler while the kayak is on edge. A shallow hull will be less affected by wind, but will carry less.

The degree of curvature in the hull from the bow to the stern along the keel line defines the amount of rocker in a kayak. This improves the ability to maneuver the kayak, especially in rough water. While more rocker increases maneuverability, it also reduces the amount of waterline in the water, creating a less efficient hull. A kayak with little or no rocker will track very well, but can be more difficult to maneuver. The cross section determines the initial feel of the kayak. A round hull is but very unstable while a flat hull is initially stable but significantly slower. Some kayaks have a "V" hull with slightly flared sides. The "V" shape gives structural rigidity to the hull, improves tracking, has a lively feel and delivers very comfortable stability. Some kayaks have a shallow arch bottom have a little more stability.

There are a variety of cockpit styles used. Their dimensions and shapes depend on the purpose of each kayak and the comfort of the paddler. The open cockpits are very easy to get in and out. The recreational cockpits are long enough so you can easily stand on the floor in front of the seat and sit down. The keyhole cockpits blend the openness of a recreational cockpit and the integrated thigh braces of a touring cockpit, which makes them easy to enter and exit cockpit. The touring cockpits are smaller to help resist collapsing of the spray skirt if hit by a very large wave in extremely rough water. They usually include built-in thigh braces on the cockpit rim to maximize control when edging and rolling. The ocean cockpits are much smaller than a touring cockpit and are very resistant to rough water and weather conditions.