Another one of those small qualification things sailors do in their spare time to get an extra point on an advancement exam. Enlisted Surface Warfare Specialist often pronounced E-swas.

This pin is awarded to a sailor after he has qualified on the ship he is stationed on. This pretty much means he has come over this ship with a fine tooth comb and learned as much about it as he can and has obtained numerous signatures to prove he has done as he says. Then he takes a series of exams to prove he has the knowledge to be awarded his pin.

I dare say it is similar to the dolphins a submariner earns onboard a sub, but I will get blasted by a submariner for doing so. The surface pin requires the sailor become familiar with every aspect of the ship. This includes operation, supply, admin, engineering, weapons, everything.
During my time it took 6-12 months to actually work through the book and get your exam taken. Once you received the book you only had a year to finish it. Some of the signatures required were as simple as sign my book. Others required hours spent with the person qualified to sign.

OPNAVINST 1414.1D dated 15 June 1998 makes it mandatory fro all sailors paygrade E5 and above to have an ESWS pin or they will not be allowed to reenlist. Each sailor who does earn his ESWS pin is allowed to use the special designator after his rate/rank, GMS2(SW) Adams.