Bought the beach cleaners knife as a safety knife for sea kayaking about a year ago and carry it in my buoyancy aid every time I go out. Was a little bigger than I originally wanted but has proven to be very robust and useful and fits into the pocket just fine.
It certainly proved its worth last week, we have a little 22ft yacht and I reversed into our mooring lines, which wrapped themselves tightly around the prop. I had to jump over the side and cut off all the rope, floating 5ft in very murky harbour water.
The knife cut through the mooring lines (nylon rope) very easily and was easy to handle while working blind. The perfect knife for sailing or kayaking, so razor sharp would easily cut a finger off if careless!