RedactedNarrative: While operating at cruising speed lower unit struck underwater object. Unknown object came in contact with transom below waterline. Rubber boot located on transom became damaged and leaking water into boat. Operator drove boat onto bank to avoid sinking. Damage is done to transome, rubber boot and water damage to inboard engine and upholstery ,rear seats and carpet. (see attached photo of Lake Shelbyville) Photo from Google Earth shows the point of inpact and the point where the boat came to rest, on the shore, in relationship too Cole Shaft Bridge.