What does SOS mean when you are on a ship?

The letters SOS in Morse Code mean HELP.

'SOS' is the morse code international distress signal. It doesn't actually mean anything but is simply a combination of two easily-distinguishable letters: 'S' (...) and 'O' (---).

The assumption that SOS in Morse code means anything in Words is a fallacy. The letters were chosen because of the ease of transmission and the distinctive sound of the repetition which is easily recognized in any language.