MacGregorSailors.com

Great news Harry - almost certainly from that stint in the vice, enamel being pretty much inflexible of course....

Good chance its the vise (I put my skeg in a vise to hold up the lower unit while I change the water pump) but I woudn't rule out a solid rope (capable of thousands of lbs of force before breakage) compressing a hollow aluminum casting either. Aluminum is quite soft and weak and a good rope is quite strong.