My friend who works at the Marine Mammal Rescue says the reason whales do this is to scratch their backs.
--- On Wed, 7/21/10, Phil Agur <[email protected]> wrote: Some friends with a Catalina 36 were stuck off Mexico when a whale came up under them. They felt the stern lift a bit and then 30 seconds later the auto helm sounded. The rudder was split at the top and driven up the shaft locking it in place around the V shaped stub molded into the hull above the rudder.
