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Navigation Lights on our Explorer Yacht

Updated: Apr 20, 2023

Happy New Year to everyone, a year of change for us is coming!

After we sketched out the basics of our navigation mast and located all the major components, the time came to assemble the Navigation Light specification and place them appropriately. We are being certified under UK Marine Coastguard Agency as Category (0), the UK interpretation of COLREGs 1972 is MSN 1781 and its amendments. Not the most scintillating read, a bit confusing at times, but also a set of rules that every navigator needs to know and understand. MSN 1781 covers rules of the road, navigation lights, horns, and an ethos that accidents will be your problem, so avoid them. A copy of MSN 1781 can be found below.

msn 1781
Download PDF • 512KB

Armed with this, here is how the navigation light requirements flow.

Firstly, to define ourselves by what we are not. Not a fishing boat or trawler, pilot boat or skiff, pusher or a puller tug or a dredger. We are not "constrained by draft" or "sweeping mines". Vanguard is a motorboat, and the length category is 20<>50m.

That makes life relatively clear. So we know this category will have 2NM or 5NM range lights, marine-approved, watertight, consistent illumination LEDs.

The case for double lights in the event of failure probably passed on vessels out of Class with the introduction of LED at circa 10,000 hours between failure. Besides this, we have an alarm if it happens en passage - so single bulb units and a spare LED or two.

Vanguard is fitted with a Praxis Navigation Light controller and has some preset conditions covering the lights we need.

Those are:

  • Steaming

  • At Anchor

  • Not Under Command (NUC)

  • Naval Yachts suggested we also add RAM, Restricted Maneuvering; not sure why, diving maybe but I was in a good mood, so I agreed.

  • Individual Operation

Shown - example of a Navigation Light Controller fromPraxis Automation.

So let's look at the requirements of each in succession:


  • Mast Head Light, 5NM, white, 225 degrees forward

  • Stern light, 2NM, white, 135 degrees aft

  • Portlight, 2NM, Red, 112.5 degrees port forward

  • Starboard light, 2NM, Green, 112.5 degrees starboard forward

At Anchor

  • Anchor Light, 2NM, white, 360 degrees

NUC (Underway)

  • 2 Mast Lights, 2NM, Red/Red, 360 degrees

  • Stern light, 2NM, White, 135 degrees aft

  • Port light, 2NM, Red, 112.5 degrees port forward

  • Starboard light, 2NM, Green, 112.5 degrees starboard forward

NUC (Stopped)

  • 2 Mast Lights, 2NM, Red/Red, 360 degrees

RAM (Diving)

  • 3 Mast Lights, 2NM, Red/White/Red, 360 degrees

3 views of the near complete arrangement. It's a bit hard to see the small lights but there are fitted. The two large square units on the front of the roof are OneWeb phased array communication aerials.

Our mast is perhaps becoming crowded, but luckily, we can fit these lights under the surfaces as easily as above. There remains an issue, however, of interference from the mast itself. We solved this by placing a requirement for 360-degree lights as two by 180-degree lights on either side of the mast struts—a small cost bump for a robust solution, probably an insignificant cost if we needed it.

There some additional rules around alignment and spacing of lights that we need to work through but in essence we appear to be complete. Time will tell.

Chris Leigh-Jones

Writing these Blogs is cathartic. We may believe in an understanding but in putting pen to paper, we begin to feel the weakness that exist. Should any reader have an exception or wish to add their thoughts, "up and at em", as Nelson once declared.

Happy New Year to all.

Useful Links for Navigation Light suppliers:

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