There are many misconceptions about kayak design, but probably the most common in my experience is about speed. As a displacement hull, all kayaks are limited in top speed by the length of the waterline. This however is of little relevance to anyone except racers, because it does not take into consideration the amount of energy required to make the kayak reach that speed. Design considerations that reduce wetted surface, and more importantly wave and eddy making drag, are far more effective in making a kayak "fast".

If a kayak with a 17 foot waterline can go 5.8 knots and a kayak with a 15 foot waterline can go 5.5 knots, but 90% of the time you are paddling you will travel between 3 and 4 knots, then the kayak that is "easier" to paddle will seem that much faster. I think this realization has led the trend to shorter kayaks in general that are lighter and easier to handle in all conditions.