Don't bet your life on that........remember the USS Cole?
way different situation there skippy... the french ship was underway, in a wartime setting. It should have had all radars and look outs up and running. And a boat that small would have still likely slipped through. Its barely taller than the waves making it almost impossible to see.
The USS Cole was refueling in and had boats pulling along side the entire time for what we call "hotel services"