My father always carried a pocket knife on his person, maybe it was something to do with his generation and him being the son of a Scottish village joiner. As for me I do carry a knife with me almost all of the time, however it's not for personal protection or whittling wood as I never joined the scout movement. My knife is on my car key ring and it's the 'baby' of the Leatherman range. It’s correct title, appropriately enough, is the Leatherman Squirt. Even though it is only 57mm long when folded it packs a big punch with it’s pliers, knife, scissors, file... in fact nine tools in all! I cannot count the number of times it has got me out of trouble, such as, a simple task like sending a tape measure up a mast to measure say a halyard and the shackle pin is wound up tight and the pliers have been 'borrowed' from my riggers kit bag. On many occasions the little Squirt has saved the day, open it up and there is an excellent pair of stainless steel pliers to hand. Small yes but perfectly adequate, not to mention again the, knife, scissors etc etc.
On the Mystery we do have a Leatherman Wave just inside the companion way, if working up at the pointy end or going aloft it's first into the zipped pocket of my Musto shorts, however our emergency deck knife is secured to a vertical tube on the pushpit ready for immediate deployment. I have been banging the drum repeatedly about this brilliant stainless knife that has a razor sharp 'straight' blade (see below how it cuts with ease through 16mm braid on braid and high tech Dyneema). The other blade, which is serrated, is perfect if you want to attack for instance a heavy duty polythene bag or a lobster pot danbuoy float wrapped round your stern gear or rudder! Handle with care, yes, but note there is no sharp point to this beast, no chance of stabbing yourself with this blunt end! Finally if you do a bit of fishing over the stern and are lucky enough to catch yourself some supper, at the end of the handle is a dispatcher, hope you get my drift!
The emergency deck knife comes in a solid bright yellow rigid holder (easy to spot when it's dark) and two fixing straps are included. As for maintenance, all stainless will 'rust' if the surface is contaminated, be it dirt or say fish scales, so before returning to the sheath wipe it clean and then rub the surface with a tiny bit of oil on a piece of rag.