Ever see a canal lock in operation, riVeRraT? Pretend for a moment that the canal lock is simulating the "fountains of the deep" that are spewing forth from the bowels of the ocean. Any estute boat operator will place fenders along side the hull to keep his boat from banging into the walls of the lock. Why? Because the force of the water rushing into the lock from the bottom water vents will give any unsecured boat a rough ride. I'm not including wind or rain. Just rushing water in a container that's maybe a 1000 feet long or so and 50+ feet wide. Now apply that concept to a global flood where Planet Earth is the lock and the fountains of the deep are the bottom vents. Still no waves? Really?
BTW - Noah and his crew would be hard pressed to fend off the Ark from crashing into mountain walls as the Earth filled. Try to keep a boat the size and weight of the Ark from smashing itself to pieces with long poles and rope fenders. Remember. No oars or sweeps. No rudder. No Evinrude outboards. Nary a tugboat in sight.