Ahead vs astern: what do they mean?
Ahead means in the forward direction beyond the bow. Astern means in the aft direction beyond the stern and can also describe a vessel moving backward.
Related terms
How it works
Unlike bow and stern, which are parts of the vessel, ahead and astern describe direction or motion. A contact can be dead ahead even when it is still far from the bow.
The distinction is especially important for sound signals. Three short blasts mean “I am operating astern propulsion.” They announce what the machinery is doing; the vessel may still carry forward way before she stops and begins moving astern.
Direction beyond the vessel
Extend the vessel’s centreline forward past the bow and it leads ahead. Extend it backward past the stern and it leads astern. On board, fore and aft usually describe positions or movement within that same frame.
On the water
- A vessel dead ahead lies on or close to your forward centreline.
- A skipper engages astern propulsion to reduce remaining headway.
- An overtaking vessel approaches from somewhere astern of the beam.
Common mistake
Three short blasts do not mean “I am already moving backward.” A large vessel may still be moving ahead while her engines work astern.
Remember it
Bow → ahead. Stern → astern.