The O'Hara Corporation rental offices are located on Tillson Avenue in Rockland, about two blocks from Main Street.  Rental spaces range in size from 600 square feet to 6,000 square feet.  Most offices have water views, as well as parking and air conditioning. Currently open: • In the former Prock Marine building -620 square feet, two rooms, first floor, separate entrance      $550/mo. -587 square feet, three rooms and bathroom, first floor      $500/mo. • In the North Lubec building    -3087 square feet, first floor               $3000/mo.         Current Tenants: -Bay Counseling Associates -Coastal Publications -Demers Chiropractic -Sawyer and Whitten Marine Electronics -Target Marketing -WBACH Radio Rockland, ME                                                         Seattle, WA