I'm revisiting this thread...
Does sound like a breakdown in communication.
I wonder if crew can be held responsible for not informing the captain properly??
Seems to point to the necessity of having something really tangible - like distress flares or smoke to signal emergencies.
After reading this, I am not convinced that a signal mirror would have changed the outcome of events.
Pete2
If it's true the bridge didn't see the boat, then the value of a signalling mirror is the moral of the story here.