hitTest1

actually some logs are moving on the water.with the help of logs my monkey should reach the other side.
logs are movieclips,water also an movieclip,monkey also an movieclip,
how should i achieve this thing?
if monkey hit with logs,it should stick it on,
if it not hit with logs that is if it hit with water,my game should over.
so using hittest ,how will i do this?