Possible Clues:

• Doctor holding right blade, one scooping out unwanted material
• Doctor is over the limit on river boat
• Would the doctor be the one sidling along to get to the bottom of it?
• It clears beds for a sprinkler
• Container with a perforated top for sprinkling flour, sugar etc
• One moving earth underwater
• Channel deepener
• Waterway excavator
• Canal-clearing vessel
• Visibly embarrassed to visit capsized registered vessel