What flora said. Start looking up local artists and find a good one with a style you like. Give them a few pictures of ships you like and they'l work it into your already existing tattoo.
Also, why don't you want it done on photoshop? You'll get better lines and it'll be easier for the artist to trace in the shop.
Regardless, this looks like something that will take a bit of free handing...
You said it yourself; it'll be on your body for life, get someone who does this for a living to design it for you
This post was edited by CHurley on Jun 27 2012 01:15pm