cracked rudder

[aasault]

A recent haulout of a 1985 Dehler 101 (tiller steering) showed significant cracks in the rudder. The cracks are on both sides of the rudder, right where the rudder post enters the rudder. The cracks are about six inches long, running with the rudder post. To my untrained eye, the cracks have the appearance of being cuased by lateral forces.

The yard is going to grind the cracks down and resurface the rudder. The rudder bearing(s) is going to be replaced.

Any clues on what would these cracks? Is this a relatively common problem for certain sailboats?

Thanks

Art