Lights and Shapes on Vessels

Nighttime can be a beautiful time to go boating. However, night vision is not the same as day vision and so rules have been established to ensure safety. Regardless of visibility, due to nighttime, fog or cloudy conditions, garish distracting city lights, or clear romantic moonlit skies, boaters need to know their colors.

Powerboats, large shipping vessels, and vessels at anchor will display a variety of lights and shapes. All of these are providing essential information to help avoid collisions. 

Photo Courtesy of Bob Grieser

Night Motoring Requirements

Your responsibility, when operating in diminished lighting conditions and after sunset and before sunrise is to turn your navigation lights on. Don’t assume they are working – the sea salt environment is a poor environment to expect electrical contact to continuously work. Visually check for operation after you turn them on.

All vessel types have a unique distinguishing set of lights that they must adhere to depending on the type of vessel. i.e. Sailing, towing, fishing, restricted in ability to maneuver, constrained by draft, dredging, etc. It would be prudent for you to learn all the differences in these lights – hint some are on the test. However, there are Apps, lookup charts, and tools that you can stow on board so that you don’t have to rely on 100% functionality of your brain cells.

Reference Tools

A good tool by Weems and Plath is the light slide rule available at
https://www.landfallnavigation.com/w-p-lightrule-colregs.html

You simply slide the card in its sleeve until you see the matching set of lights to your observed vessel.

Apps

With the free NauticEd App you can navigate to this page anytime to review lights on vessels. Download the NauticEd App now if you have not already.

There are also some other Apps available. You should download one now – you never know when you will need it.

Here is one for iOS

ColRegs: Nav Lights & Shapes for Boating and Sailing

Or for Android

https://play.google.com/store/apps/details?id=com.imar.nav3d

On The Web

The lights for all vessels are covered in the Navigation Rules printed by the USGC and apply to international rules as well. They are Part C Rules 20 through 31.

You can get the latest version in book format from amazon.com. Or download the Kindle App to your smartphone and get the Kindle book version of the rules also from Amazon.

The Rules for Vessels

Power Vessels (less than 50m) Underway:

• One all-around viewable white light
• Red (on port) and green (on starboard) sidelights viewable from dead ahead and 112.5 deg abaft

At night you would see this boat traveling as such:

Power Vessels at Anchor:

• One all-around viewable white light

Sailboats

Powerboaters should be especially on the lookout for sailing vessels as they are commonly out at night. The lights for sailboats are similar with a few exceptions

For sailing vessels that are sailing, the lights required internationally are:

• Bow – red (port side) and green (starboard side) with a 112.5 degrees arc – remember “is there any red port left”
• Stern – white with a 135 degrees arc (instead of 360 degrees on a powerboat)

Rule 25 for sailboats also allows for the combining of the lights into one lantern.

b) In a sailing vessel of less than 20 meters in length the lights prescribed in Rule 25(a) may be combined in one lantern carried at or near the top of the mast where it can best be seen.

This is sometimes referred to as a tri-colored light. Note that it is a replacement for the bow and stern lights not “in addition to”.

Sailing Vessels at Anchor:

• Anchor Light  – white 360 degrees at the top of the mast (for anchored only)

Sailing Vessels under Power: (A 225 deg forward-facing white light mounted on the mast is added to the sailing arrangement)

• Bow – red (port side) and green (starboard side) with a 112.5 degrees arc – remember “is there any red port left”
• Stern – white with a 135 degrees arc
• Mast head – forward facing white 225 degrees mast mounted (for under power only sometimes called a steaming light) (this 225 deg plus the stern 135 deg = 360 deg)

A sailboat under power is considered under the rules as a powerboat. But many times they might still have up their sails. It is thus difficult to determine if they are technically a power or sailboat. If a sailboat is under power and greater than 12m (40ft) is supposed to display during the day an upside down cone on the forestay. This indicates to others to treat it as a powerboat for give way rules purposes. In general, it is a rare experience to see large sailboats displaying this despite the requirement. As a powerboat approaching a sailboat under sail, you should steer clear.

At night, generally, you will find that sailboats that are under power do turn on their forward-facing white steaming light mounted on the mast. When you see this, treat them as if they are operating under the powerboat rules – but as always be aware and be prepared to steer clear if they are not making an early and obvious direction change to avoid colission.

Optional – Masthead 360 degrees red over green in addition to the lights on the bow and stern

Here are some examples of actual lights to be mounted on vessels:

Individual red and green or Bi-Color to mount on forward bow rail plus a white stern light and all-around white. Note that angles are preset into the light housings.

At night the danger is heightened because distances are hard to determine. Therefore, a keen lookout is required and actions must be taken early. Determine who is the stand-on (right of way) vessel and make any course changes you perform early and obvious and unambiguous. 

A good rule of thumb to use once you spot a light is to first ascertain which side of the other vessel you see via the color of the light. Then watch the compass bearing of that light relative to your vessel. If the bearing is unchanging, then you are likely on a collision course.

Other Vessels

Where required, the “By Day” shapes are shown in the white circles on the image.

Large Power Ships over 50 m

Same for Power Vessels except for the addition of a forward-facing mast light. In addition, in general, for all power boats below, any time you go over 50m in length you need to add another forward-facing mast light.

What you have to be cognizant of is being able to imagine what this looks like at night.

For example, the container ship bearing down on you in pitch dark with look like this below. We certainly hope that you never see this.

Virtual Reality Training

In our Virtual Reality training program, we have a night maneuvering mode whereby you must navigate through a series of ATONs at night using only their flashing lights to identify them. This is real experiential training and is highly recommended. See our Virtual Reality course instructions here.

Diving

Two ‘diver down’ flags that you need to be aware of to indicate that this vessel has scuba divers below. You are required to stay 100 meters away from such a vessel.

In the USA the red flag with a white strip is used

In most of the rest of the world, the Code A flag is used