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Obeying The Buoys

Dec 20, 2017

Author: Fin

Fintan Hartnett is the Principal and Chief Instructor at Topmast Maritime Training and an RYA Yachtmaster Instructor as well as Sail Canada and ASA instructor.

No one possesses the literary skills to make the subject of buoyage interesting – no one. Buoys, their markings and light attributes are a dry subject and a necessary evil in maritime training schemes. Still, getting them wrong can have very real repercussions. Positioning yourself on the wrong side of a lateral or cardinal mark is going to hurt – or is it?

Buoyage comes in different shapes and sizes, as do boats. Some (if not most) buoyage is positioned for the benefit of large vessels with deep drafts. Thus, a lateral mark (starboard/port buoy) which delineates the navigable parts of a well-travelled channel is probably there for commercial shipping and not necessarily small recreational boats. Whereas the lateral marks in a shallow tributary in the middle of nowhere may be there for the benefit of smaller craft only. Without referencing a chart, or having the benefit of local knowledge, it’s not always easy to determine which is which, though common-sense helps. 




 In shipping channels, small vessels are expected to keep to the far side of the channel (Rule 9 in the IRPC’s) or even to the outside of the lateral marks, so as not to impede the passage of larger, draught constrained vessels. This is good and safe practice under the circumstances, provided there’s no danger to the smaller vessel.

Crossing inside a cardinal mark is almost certainly a riskier proposition and, generally, uncalled for under almost any circumstances, regardless of the size of vessel. Does this mean the area defined by the cardinal mark is unnavigable? The simple answer is: maybe. The cardinal mark may be guarding an underwater rock, wreck or other obstruction which may be sitting 3 metres under the water – a threat to large vessels but not small vessels with shallow drafts. Under these circumstances the only reason to be inside the mark would probably have to do with fishing or diving and almost certainly depend on possessing good local knowledge.


Conversely, it is wrong for anyone to assume all dangers are marked. Or, for that matter, that all channels are marked. The authorities tasked with arranging and maintaining buoyage face the same budget constraints as any other government department – if not more, in cost-cutting times. More reason to navigate with due caution, especially in unfamiliar waters.

When navigating tidal waters, or the Great Lakes, where water height varies significantly, it is important to understand the impact the change in depth can have upon buoyage.

How far sailors choose to venture off the beaten track (guarded by lateral and cardinal marks) is part and parcel of becoming a good Navigator. Even if it’s just for the sake of poking around and satisfying a bit of curiosity there are some important things to bear in mind. 

  • Use charts to understand where the real dangers lie.
  • Use the right scale of chart so as not to miss any dangers (zoom-in if you’re using a chart plotter).
  • Use the depth sounder (in North America, know if you’re using feet, fathoms or metres AND know whether ‘0’ is set to the keel or waterline).
  • Use common-sense (and your eyes).
  • Practice safe speed.
  • If you have the available crew, place someone forward.
  • Have the engine on.
  • Don’t get ‘boxed-in’, have an exit strategy (reciprocal course usually works).
  • Ask the local mariners what they know. 


Lastly, understand the marks around you and their relevance to the type and size of vessel you are operating. Take nothing for granted, it will make for a better day at the office.

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