Originally Posted by whisper
I guess if you went on a cruise for lunch somewhere then it would be better for you to take it with you and not leave it onboard and therefore you would have a good reason to have it on your person.
The round tipped ones with the chunky floating handle are very obviously a specialist knife with a blade of aprox 3". While you cannot guarantee that you wont be given a hard time, it would take a very bloody minded Policeman to insist it was being carried without good cause.
Another thing worth having is Tuffkut scissors, they are effectively disposal at a couple of quid but they will cut through anything (famously even a 1p piece). Very handy things, used by everyone from angler charter skippers to paramedics.