U.S. Coast Guard Marine Safety Manual -
Chapter 4 addresses Physical Requirements for Mariners. This is a
large file, and may take a few minutes to download. NVIC 04-08
supersedes the Marine Safety Manual where the two conflict.
Calculate Body Mass Index
http://www.nhlbisupport.com/bmi/ - Most doctors will already have
this, but this link provides a calculator to compute Body Mass Index.