Knives that are purpose-built are cool. I sail, when I can, and found the Boye folding sailing knife to be a philosophically perfect sailor's knife.
The metal is dendritic cobalt steel. You always have microscopic serrations, and it melts through a line under tension. Cutting a line in an emergency can save a life, and the line will almost always be under tension when it has to be cut.
The knife is blunt-tipped, so you won't stab yourself on a heaving deck. The blade is mostly serrated, a little plain (and all nano-serrated with cobalt). The blade locks, it can be opened and closed one-handed, it's got a lanyard loop. On one side is a pocket clip, on the other a marlin spike with a tapered slot to open stubborn shackles. The handle is bright yellow so you can find it in bad conditions.
The features of that knife are a one-to-one fit for my list of what a proper sailing knife should have. It's not a knife for repelling boarders, but for general work and thwarting Davy Jones, it's a perfect knife.