Planing hull

A hull shape when, at planing speed (see below), planes or slides over the water's surface. The bottom of the hull is typically flattish with hard chines.

In kayaks, this surfboard-like shape that is ideally suited for surfing ocean or river waves--contrasted with a displacement hull. Different manufacturers modify this basic theme: concave, tri-, channeled and spin disk planing hulls. Found on surf specific and whitewater boats.

Strickly speaking, many kayak designs are not planing hulls, but surfing hulls. They are optimized to surf on a wave but do not necessarily meet the technical definition of planing. Unfortunately, common terminology blurs this distinction and many paddlers refuse to accept the proper term.

Planing occurs well after a hull reaches hull speed. Hull speed is defined as a speed/length ratio - ^speed/_√length - of 1.34. Planing starts at a speed length ratio of 1.5 and true planing occurs at higher speeds. If speeds of surfing kayaks are estimated, it is possible for them to plane. However, they often reach high speeds less than planing speeds and still above hull speed - the sensation is much the same to the paddler and they are surfing. Ordinary sea kayaks can easily be surfed on waves but their hull shapes make true planing difficult. So it is possible to surf, to plane or to just go fast. Regardless - it feels good!