IRPCS Shapes


Under the IRPCS  many vessels are required to display shapes by day to signify where they fit into the rules. Exam candidates are expected to learn these shapes. We have highlighted the most common shapes in the table below.

By Day Tye of Vessel Notes
Diver Down* Flag “A”
At Anchor* Ball should be positioned in the bow of the vessel. Not required under 7m
Motor Sailing* Required if sail(s) are hoisted but the yachts is operating under power (i.e. engine runing)
Towing* If tow is under 200m, only the tug displays diamond. If tow is over 200m, last vessel in tow also displays a diamond
Restricted in ability to manoeuvre* Restricted in ability to manoeuvre due to its work (i.e. dredging, cable laying etc.
Restricted in ability to manoeuvre due to its to work* The shapes tell us she is “Restricted in ability manoeuvre,” due to her work. Image tells us this is due to the tow.
Restricted in ability to manoeuvre but clear to pass on the port side * Restricted in ability to manoeuvre. Pair of diamonds denote the side which is clear to pass
Constrained by draught* Can only operate in the deep water channel
Not Under Command* Unable to comply with IRPCS due to a steering or machinery fault
Fishing or Trawling* The wineglass shape denotes fishing vessel. Additional cone pointing upwards signifies outlying gear extending more than 150 metres horizontally.
Mine Hunter * A navel vessel engaged in mine clearing


The observant reader will have noticed that each shape has a coloured dot next to it. Either * or *.

RYA Day Skipper Shorebased students should be aware of all of the shapes but focus on remembering the top four (*)

I suggest that RYA/MCA Advanced Powerboat COC, Yachtmaster Coastal, Yachtmaster Offshore, Master 200 and  OOW3000 (or higher) candidate should know all of the shapes (* & *) .

Trawler displaying its anchor ball


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