Engine rotation is viewed from the flywheel of the engine, clockwise would be Right Hand, and counter-clockwise would be Left Hand.
Since you usually cannot see the flywheel with the engine in the boat it can also be determined from the front of the engine. If you are looking at the front of the engine at the belts and pulleys, clockwise would be Left Hand, and counter-clockwise would be Right Hand. Never rely on propeller rotation to determine engine rotation. ALL I/O ENGINES ARE LEFT HAND!