to fend off a boat

from The Collaborative International Dictionary of English v.0.48

Fend \Fend\, v. t. [imp. & p. p. {Fended}; p. pr. & vb. n.
   {Fending}.] [Abbrev. fr. defend.]
   To keep off; to prevent from entering or hitting; to ward
   off; to shut out; -- often with off; as, to fend off blows.
   [1913 Webster]

         With fern beneath to fend the bitter cold. --Dryden.
   [1913 Webster]

   {To fend off a boat} or {To fend off a vessel} (Naut.), to
      prevent its running against anything with too much
      violence.
      [1913 Webster]