Your vessel is backing on the starboard...

Your vessel is backing on the starboard...

Question 1 of 2707066636ee728f7522a1c518edb

Your vessel is backing on the starboard screw, and going ahead on the port screw. How will the vessel react?

Question 1 of 27070

Q

Your vessel is backing on the starboard screw, and going ahead on the port screw. How will the vessel react?

🔍 Key Concepts

• Effect of a single right-hand (starboard) screw going astern on the vessel’s stern and bow • Effect of a single left-hand (port) screw going ahead on the vessel’s stern and bow • Resultant turning moment when two screws are turning in opposite directions (one ahead, one astern)

💭 Think About

• First imagine what the vessel would do if ONLY the starboard screw were backing — which way would the stern and bow tend to move? • Then imagine what the vessel would do if ONLY the port screw were going ahead — which way would the stern and bow tend to move? • Now combine those two effects: which side’s thrust is ‘pulling’ the stern more strongly, and what does that do to the bow?

✅ Before You Answer

• Verify the usual direction of rotation for a right-hand propeller and how it walks the stern when going astern • Verify the usual direction of rotation for a left-hand propeller and how it walks the stern when going ahead • Confirm whether the combined thrust tends to move the vessel more sideways with a swing of the bow rather than straight ahead or astern