It already looks like you have an old clock in your signature. You can just change the dates and ship name on that one.
Here is the format. Change the month, year, day and ship name and put it in your signature. Signature is access from "User CP" in upper left of the page.
Oh well - for some reason I can make it and gives me 3 options to paste it - somewhere but I can't figure it out. Sighhhhh just means I should go on more cruises to change clocks and get the hang of it!