This article is from the Sea Kayaking FAQ, by Todd Leigh with numerous contributions by others.
Single kayaks provide greater maneuverablity than doubles. Doubles can
be faster than singles. Doubles may be able to carry more gear, but
keep in mind that they need to carry more than twice as much gear for
this to be true. A double will require the use of a rudder to steer. A
double on a trip can provide an ill/injured person with a safer place
to sit than in a single being towed. Some doubles are more stable than
a single but will be more difficult to rescue and pump dry.
 
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