Related Clues:
- Preserving energy, Romans relaxed -- slaves driving galley, maybe
- A bireme has two banks of them
- Dory devices
- Boater's blades
- Dinghy twosome
- Trireme propellers
- Dinghy tools
- Rowers may have a row of them
- Things rested on, metaphorically
- Blades in lakes
- Rows with some characters getting into Arsenal
- Dinghy steering tools
- Offshore devices
- Ordinary Seaman crosses a river — boat may need these
- Crew's need