Branko: That is an interesting question and one that I thought would be easy to find the answer to. I Googled the poop out of the subject and this is the best I could find:
"SHIP’S HORN IN CLOSE PROXIMITY:
In close proximity, here are the meanings of the Ship’s Horn:
One short blast means 'I am changing course to starboard.'
Two short blasts mean 'I am changing course to port.'
Three short blasts mean 'I am operating astern.'
Two prolonged blasts followed by one short blast to mean 'I intend to overtake you on your starboard side';
Two prolonged blasts followed by two short blasts to mean 'I intend to over-take you on your port side.'
A long blast every two minutes is used when operating in fog."
I don't know if this is worldwide.
I think the ten short blasts means "I have Parkinson's Disease and my finger is stuck on the button."