When Ernest Borgnine is piloting his tug and approaching the Vega, he signals the Vega with three short blasts on the horn. According to US Coast Guard Navigation Rule 34, three short blasts on the horn indicates "I am operating astern propulsion" (backing up). He is obviously going forward and should have sounded 1 short blast to indicate "I intend to leave you on my port side", 2 short blasts to indicate "I intend to leave you on my starboard side" or the danger signal, which is 5 short blasts, if the other vessel was not following the navigation rules.