January 07 2006 at 0635 UTC in position 13:43N - 049:09E, Gulf of Aden. One speedboat, yellow colour, about 15 meters length doing 21 kts chased a chemical tanker underway. Master raised alarm, sounded whistle, increased speed to maximum, took evasive manoeuvres; crew mustered and activated fire hoses. Boat came close and seeing crew alertness stopped the chase and moved away at 0740 UTC.January 07 2006 at 0440 UTC in position 13:58.6N - 049:20.8E, Gulf of Aden. Four boats, white colour, about 15 meters length doing 15 kts approached a chemical tanker underway. Master raised alarm, increased speed and took evasive manoeuvres and boats moved away at 0505 UTC.