Onboard Communication

Good communication is key in relationships, business, and on board your boat.

Without good, solid communication relationships crumble, businesses fail, and boats, well it will become dangerous!

Where are we?

Our first foray into Moreton Bay, Noel and I checked each marker diligently. “Have you seen the green marker of the next channel?” I asked. ‘Yes, got it.” Noel replied.

He was looking over the port rail and I was looking over the starboard rail – both looking at a different marker!

A momentary miscommunication, but this highlights how easy it is to do it and how this could cause a problem on board very quickly, especially in confined waters.

Recreational Vessels

People who race use the clock method, relative to the ship. Twelve o’clock is the bow, starboard-abeam is 3, astern is 6 and port-abeam is 9. As a fellow sailor recently commented on a thread, “Anyone can yell out, at any time, “vessel at 11 o’clock”.

That is great communication. As long as everyone uses the same communication, as long as it is correct and understood it is up to you to choose how you do this on your boat.

Commercial Vessels

There are standard international conventions on commercial vessels. The language must be English and we must use the same terminology. This is used on all ships, large and small.

The International Maritime Organisation (IMO) states:
As navigational and safety communications from ship to shore and vice versa, from ship to ship, and on board ship must be precise, simple and unambiguous so as to avoid confusion and error, there is a need to standardize the language used. This is of particular importance in the light of the increasing number of internationally trading vessels with crews speaking many different languages, since problems of communication may cause misunderstandings leading to dangers to the vessel, the people on board and the environment.

Let’s look at Relative, and True, and Red/Green Bearings

Relative Bearings are Relative to the ship’s head. They are different from Red and Green bearings. Relative bearings range clockwise from 000° to 360°; Red and Green bearings range from 000° to 180° on either port (Red) or starboard (Green) side. Relative bearings are easier to convert to True.

Relative bearings: Looking straight over the bow = 000°, over the stern = 180°, port beam is 270°, starboard is 090°.

Red/Green Bearings: If a vessel is abeam on your starboard side, she is also ‘090° Relative’ or ‘090° Green’. If a vessel is abeam your port side, she is ‘270° Relative’ or ‘090° Red’.

Bearings relative true

Position fixing bearings

Read these notes (below) while looking at the diagram above.

The red line and text show the vessel’s course is 065° True.
Onboard, we would say, “heading 065° True”.
The purple line and text show the True bearing of the target (100° True).
Onboard, we would say, “target bearing 100° True”.
The green line and text show the relative green bearing (035°).

Onboard, we would say, “target bearing green 035°.”

TIP: Remember to convert all your bearings to True before laying them off on your chart.

Good communication onboard

Bearings Illustrated

Read these notes (below) while looking at the diagram above.

The purple line and text show the vessel’s course is 065° True.
Onboard, we would say, “heading 065° True.”
The red line and text show the relative red bearing of the target (Red 105°).

Onboard, we would say, “target bearing red 105°.”

Upon hearing “red”, instantly the person hearing this message will look to port. I’d start looking at approximately 090° and work my way around until I could see the target.

In reality

The target will be viewed abeam of the vessel’s port side. Most navigators/crew will be able to have a good guess at the angle without physically doing the calculations in the first instance.

We know that if a target is slightly abaft the beam it is going to be just over 90°.

The blue line and text shows the relative bearing of the target read from the radar in Course Up (CU) Mode as 255° (to the ship’s head).

On board, we would say, “target 255° relative.” (To be recorded, with the time, for chart work.)

The orange line and text show the True bearing of the target.

On board, we would say, “target bearing 320° True.” (Which is our True course (065°) plus the Radar Relative Bearing (255°) = 320°T.

In reality we would use Red/Green bearings in conversation between crew or other ships. And Relative Bearings for noting in the log, and true bearings on the chart.

Convert Red and Green bearings to True (for chart work): If you have taken a Green bearing, add this to your ship’s True heading. If you have taken a Red bearing, subtract this from your ship’s True heading.

True bearing = Ship’s heading (T) + Green bearing

True bearing = Ship’s heading (T) – Red bearing

Note: If you end up with a negative number, just add 360, as we work within 360°.


Our ship is on a course of 054° True and the first mate has spotted a vessel “target red 085°”.

Covert to True to lay it off on your chart.

True bearing      =             Ship’s Heading (T) – Red bearing

=             054° (T) – 085° (Red bearing) = -031°

=             -31 + 360

True bearing      =             329°(T)

(If you can see that you will end up with a negative number, you can add on the 360 first if you wish.) e.g. 054° – 085° + 360° = 329°

What systems/methods do you maintain on board?



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