'Midship beam' definitions:

Definition of 'Midship beam'

From: GCIDE

Midship \Mid"ship`\, a. Of or pertaining to, or being in, the middle of a ship. [1913 Webster]
Midship beam (Naut.), the beam or timber upon which the broadest part of a vessel is formed.
Midship bend, the broadest frame in a vessel. --Weale. [1913 Webster]