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The Rules of the Road

Understanding the Risk of Collision


An improperly lit sailboat. The masthead light indicates it is at anchor. The stern and running lights suggest it is under way. You have no way of knowing what this boat is doing.

Day Shapes and Night Lights

COLREGS: Part 2.

Although the COLREGS (Collision Regulations) are pretty clear about what should and should not be displayed on a vessel, they also tend to be a little obtuse, and thus open to potential misinterpretation – something we have been guilty of as well.

Even if not stated in this way, perhaps the most important thing a pleasure craft operator should remember is “Might is Right”. A really big boat, no matter what it is, has right of way over any sail or power pleasure craft – particularly in near coastal waters. These big boats will for the most part fall into two categories, which do have right of way, or are “the Stand on vessel” in a “crossing situation”. They will either have to follow the deep water channel and are thus “constrained by draft”, be otherwise “restricted in their ability to maneuver”, or they are tugs towing a barge.

As a rule of thumb, the boat that is better able to maneuver should stay clear of the vessel that cannot do so as easily.

But what about at night? There we need to rely on lights. Again there are rules as to what you should display. Adding lights may make you more visible, but it will also make identifying what type of boat you are more difficult for an observer, and may thus actually endanger you.

The lights displayed by a pleasure craft (under 20 meters) are very simple. Towards or at the bow you must have the red and green forward and side facing lights. A vessel under power, this includes a sailboat motor sailing, must have an all-around white light (if less than 6 meters). For a vessel less than 12 meters this light can be split into two parts with one being stern mounted and aft facing, and the other mast mounted and forward and side facing. For a vessel greater than 12 meters, this white light must be split in two parts.
A sailboat under 20 meters sailing at night may alternatively have running lights fore and aft, or a tricolor at the masthead.

A sailboat sailing (without motoring) must switch the latter one off, so it is not confused with a power driven vessel. As the rules defining the stand-on and give way vessel apply during the day as well as when it is dark, there is one requirement you way only rarely see adhered to for sailboats. When a sailboat is motor sailing, it must display a black cone with the pointy end down in its fore triangle.

Sailboat under power at night

Sailboat under power at daytime

Powerboat under power at night

Small boat (less than 6m) under power at night

If you now see a vessel with these lights (and nothing else), you have a basis for determining whether you or the other must give way. If you see a white light and/or a red light, you must steer clear of the other – assuming that you are both under power. As it is always wiser to err on the side of caution, particularly at night, insisting on a sailboat having ‘rights’ over a power boat, is not necessarily the best choice. If you see a green light on the other vessel, yours is the stand-on boat. Again, you should assume that the other skipper has not seen you and though you should maintain course and speed, you must also be prepared to take evasive action.

When you see another boat that looks like it may cross your path at night, it is a good idea to scan a way behind it. It may just be a towboat towing a barge, and barges are not always well lit. Whatever happens, it is not a good idea to try and pass between towboat and its barge.

There really is not a lot of need to learn the sometimes complex lighting patterns required by different types of boats. Suffice to remember that is a boat is lit up with additional lights, it is safe to presume that it is a larger craft, or is in some way encumbered and that you should give it a wide berth.

At anchor things are a little simpler. Boats over 7 meters and less than 50 meters must display a white all around light at night and a black ball during the day. Other lights such as deck lights, spreader lights etc. are all permitted, and basically just make your boat more visible. The only lights you should not have on are the red and green running lights, as these would give an incorrect and dangerous message to other mariners.

Sailboat at anchor at night

Sailboat at anchor by day

Powerboat at anchor at night

Powerboat at anchor by day

In case you think using the correct day shapes and night lights is nonsense, consider for a moment what the result might be if things did go bump. We were at anchor in a lovely harbor and went ashore to explore. When we returned to our boat everything in the main salon was in disarray. The lockers had spilled out. It was a mess.

My first thought was that someone had sped past with a huge wake, but quickly discounted this, as we had just completed a long offshore passage, and had weathered some horrendous seas, without anything falling out of the lockers.

We came back on deck just as a fishing vessel came alongside. The skipper shouted over, “I might have brushed you a bit.”

We looked over the side and saw nothing. He gestured us to look further forward. There it was; a hole in the side of our boat. He had T-boned us in bright daylight.

We exchanged insurance information, and I called our insurers, explaining what had happened. Their first question was, “did you have an anchor ball displayed?”

When I answered to the affirmative they replied, “Then you have nothing to worry about.”

So, the bottom line: As we had our day shape properly displayed, the other insurance paid our costs without any question. Had we not done so, we would quite possibly have received nothing, and may have had to pay for the repairs to the fishing boat.

Please do not rely on this discussion alone. There are many more rules that apply to what one is required to do in crossing and passing situations. Please take the time to review the COLREGS and absorb the rules. To review the actual regulations and learn more, visit this site

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