Unseen Sailors

You enchant a seaworthy vessel with an unseen crew. You must concentrate on this spell for it's entire duration or the effect fades after 24 hours. 

A crew of 25 servants, considered skilled hirelings in regards to sailing, act as manning the enchanted vessel whenever summoned with their command word determined by the caster.  Each sailor can perform any task a normal human could perform, but cannot attack or harm any creature and cannot man any weaponry on the vessel.

The servants cannot fill the role of Captain, First Mate, Bosun, Quartermaster, or Cook.