How did the whale know that the rudder was the most vulnerable part of the boat? Smart buggers, ain't they? Sort of like the bears in Yellowstone:

how bears get into cars

The main method is by putting their claws into the top of your door frame and pulling down on the door, much like the lid on a sardine can opens. Once in the car sometimes they will claw through the back seat to get into the trunk. Another method is to bust your tail light out and reach into the trunk. (I read somewhere, but lost the source, of bears jumping up and down on the roof of a particular car model to get the doors to pop open, but this sounds like a not-quite-so-urban rumor.)

It's not hard to find reports of old-school boats stove in by whales... or rocks....