The Collaborative International Dictionary of English v.0.48:

Surfboat \Surf"boat`\, n. (Naut.)
   A boat intended for use in heavy surf. It is built with a
   pronounced sheer, and with a view to resist the shock of
   waves and of contact with the beach.
   [1913 Webster]

WordNet (r) 3.0 (2006):

surfboat
    n 1: a boat that can be launched or landed in heavy surf