The Boye knives are super for rope and general cutting. Watch out for people selling 440C as Cobalt. (BDS vs. BDC)
Also, if you can find one, you might consider one of the old Kershaw model 12's. Better construction than a lot of the sailors knives out there.
Also, note that many (most) of the marlin spikes offered are not heat treated, so they bend. Don't know if this is intentional, bit can be annoying when working with big stuff.