| Officer in charge of Deck |
13, 167 |
| Officer of the Watch |
13, 131, |
| 141, 145,
155 157 -
159, 243 |
| Oil in Navigable Waters Act |
92 |
| Opening and closing of hatches for ventilation |
171 |
| Orders, Commanders, obedience to |
9 |
| Overcarriage of cargo, precautions against |
178 |
|
