Young fellow working for me was first in his class from Mass Maritime to get his chief engineer ticket. Of course it was only good on one ship - the Sabino from Mystic Seaport! He'd come in after working with these burns on his forearms where he'd hit the firebox while shoveling coal. Answering bells was just that - the captain would pull a cord that would ring a small bell in the engine room. Short rings, longer rings, number, sequence all meant something different.