Contemporary Mariners have a few dedicated sailor's knives to choose from. There are the superb American Myerchins, German naval pattern made by Linder and British John Adams in sheath knives. Folders are also available from Myerchin,John Adams, Case and a few others. These knives are all stainless steel and come with a marlinespike and ( sometimes) shackle opener. They are all also somewhat expensive. A general use knife can make due, but any deck work will find the other tools lacking. There is a new/old folder on the market well worth buying for ship use. A recent supply of vintage NATO folders has surfaced. These are very substantial knifes with a properly curved marlinespike,sheepsfoot blade, combination can/bottle shackle opener and a small flat screwdriver blade integral with the frame. They are carbon steel. The best feature is price. I acquired an example from friend and dealer
www.ragweedforge.com for the exorbitant amount of $9.00+shipping <img src="images/graemlins/tongue.gif" alt="" /> You have to clean some grease and buff out a few rust spots on some examples ( mine had 3, nothing serious.) These knives appear unissued and are sharp out of the grease. Very sharp, I cut myself <img src="images/graemlins/grin.gif" alt="" />