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Every day, commercial, recreational, and military vessels encounter one another on the seas with different prerogatives—moving product as safely and efficiently as possible, enjoying a day on the water, or completing a mission, whatever that might be. This article will provide context to commercial, merchant, and recreational craft regarding the types of military craft and operations they may encounter in order to make better-informed maneuvering decisions.&nbsp;

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Anticipated Locations: U.S. Navy surface vessels sail around the globe—however, the highest density areas are: Everett, Washington; San Diego, California; Pearl Harbor, Hawaii; Mayport, Florida; Norfolk, Virginia; Rota, Spain; Yokosuka, Japan; Sasebo, Japan; and Manama, Bahrain.&nbsp;

Bridge Manning: Military vessels in the U.S. Navy Surface Fleet are not manned in the same way merchant vessels are. It is common during normal operations for there to be upwards of seven watchstanders on the bridge at any given time or upwards of ten during special operations (Sea &amp; Anchor Detail, Underway Replenishment, etc.). During normal operations, it is common to have an Officer of the Deck, Junior Officer of the Deck, Conning Officer, Helm, Boatswain’s Mate of the Watch, and two lookouts. Expect delays in responding to radio calls as each Captain has different reporting requirements that may require the Officer of the Deck to contact them before responding.

When Vessels Meet: Military vessels will generally have a greater factor of safety regarding the closest point of approach than their civilian counterparts. Commercial vessels should anticipate earlier and more frequent radio calls than may be expected in the vicinity of commercial or recreational traffic. Unlike commercial traffic, military vessels are often not traveling at the same consistent course and speed. If such vessels are operating on a mission or conducting a training exercise, you may see what appears to be significant course and speed changes in short iteration.

Operating Aircraft: Commercial vessels should be aware that some military vessels will frequently be conducting air operations. As mandated by the COLREGs, military vessels will display&nbsp;Restricted in Ability to Maneuver&nbsp;when conducting air operations. When conducting training, it is common for military vessels to maintain the same course and speed for long stretches so helicopters can practice “touch downs.” Aircraft carriers may maneuver in a racetrack-type approach, launching and landing fixed-wing aircraft and then resetting before beginning again. Under certain circumstances, smaller vessels (cruisers/destroyers) might trail behind a carrier during air operations serving as the horizon reference unit.

Live Fire Exercises: When military vessels are conducting live fire exercises (missile shoots, five-inch gun, small arms, etc.), they will always make multiple warning calls over VHF Channel 16. Military vessels may request commercial or recreational operators in their vicinity to declare their maneuvering intentions. It is common to see military vessels transit at slow speed down a designated “firing line” before speeding up to reset and begin firing again.&nbsp;

Underway Replenishment (“UNREP”): A common method for resupply of military vessels is underway replenishment (for both fuel and stores). The vessel and the supply ship generally choose a course and speed to maintain for up to a few hours. Commercial and recreational vessels operating in the vicinity of an UNREP should anticipate an early radio call as maneuvering and speed changes are restricted during UNREP and can only be done in small iterations (one degree course change, one RPM speed change, etc.) There may also be air operations simultaneous with an UNREP.&nbsp;

U.S. Coast Guard surface vessel operations are similar to those of U.S. Navy surface vessels, but their multi-mission capabilities introduce additional considerations for commercial or recreational vessels operating nearby.

Coast Guard vessels are designed to transition seamlessly between various mission sets. For instance, a Sentinel-class cutter in certain Areas of Responsibility might start the day with recreational vessel safety boardings, shift to a search and rescue mission in the afternoon, and conclude with immigration enforcement operations in the evening. These diverse operations often require the rapid launching and recovery of small boats, sometimes with little notice. Therefore, commercial and recreational vessels should be prepared for Coast Guard vessels to change course and speed suddenly and should maintain a wide berth around such operations.

Additionally, the Coast Guard’s law enforcement activities can result in unique lighting configurations. While Coast Guard vessels are generally required to display navigation lights between sunset and sunrise or during periods of restricted visibility, there are exceptions. When conducting specific law enforcement or public safety operations, Coast Guard vessels may operate without certain navigation lights. Commercial vessels or recreational vessels that encounter a Coast Guard vessel without normal navigational lights between sunset and sunrise should keep a wide berth and avoid hailing them on the radio about their lighting configuration, as this could compromise their operations.

U.S. submarines operate globally but, except for entering and leaving port and in certain limited circumstances, they do so while submerged.

Operating Areas: Submarines are most often found operating on the surface in the vicinity of U.S. Navy homeports in Groton, Connecticut; Norfolk, Virginia; Kings Bay, Georgia; Bangor, Washington; San Diego, California; Pearl Harbor, Hawaii; and Apra Harbor, Guam.

The United States operates three types of submarines, all nuclear powered: attack submarines, ballistic missile submarines, and cruise missile submarines. Although each type of submarine carries different weapons and has different missions, for the purposes of understanding their actions on the surface, they operate identically.

While submarines can operate in shallow water, submerging in less than 100 fathoms (600 feet) presents challenges, such as the difficulty in avoiding vessel traffic that may not be aware of the submarine’s presence, or the possibility of bottom contact. As a result, when proceeding to sea on routine operations, a submarine will usually delay submerging until it reaches an area where the water depth is at least 100 fathoms.&nbsp;

Bridge Manning: When on the surface, submarines are usually conned from the bridge at the top of the “sail” (also called the “fin” or “fairing” by the Royal Navy but no longer called the “conning tower” as it was during World War II). The bridge will be manned by an Officer of the Deck and a lookout, and during some maneuvers the Captain will also be present on the bridge. The Officer of the Deck or the Captain gives orders from the bridge cockpit to the Helmsman below in the control room using a public address type of announcing system or a sound-powered telephone. In addition to the Helmsman, the control room will be manned by a radar operator and fire control watchstander who tracks other vessels, a Quartermaster who keeps track of the ship’s position, and a Chief of the Watch who operates the ship’s mechanical systems. A ship’s officer will be assigned as the Contact Coordinator in charge of the Control Room to maintain a lookout using a periscope, and to assist the Officer of the Deck on the bridge in deciding on collision avoidance maneuvers.

During heavy weather, such as when waves break over the top of the sail, the bridge watch is sometimes moved below deck and the Officer of the Deck conns the ship from the Control Room, similar to when the submarine is submerged. When this occurs, however, the lookout’s view is limited to what can be seen through the periscopes.

When Vessels Meet: A U.S. submarine, when operating on the surface in narrow channels or areas with limited depth, is treated as a “vessel constrained by her draft.”&nbsp;This means it is severely restricted in its ability to deviate from its course due to the available channel width and water depth as compared to its draft. It will display a black cylinder day shape and also may display three all-round red lights in a vertical line in addition to the lights required for a power-driven vessel. It also may display, as a distinctive means of identification, an intermittent flashing amber “Sub ID beacon.”

A surfaced submarine can be tracked using commercial radar systems, even those not specifically designed for military applications. The submarine’s hull, periscopes, and antennas will reflect radar signals, making it possible to detect the submarine. Visual identification, however, especially at a distance, can be challenging. Although surfaced submarines have unique structures like a sail, radar masts, and antennas unlike those typically found on surface ships that can help differentiate them from other vessels, because of its low freeboard, surfaced submarines are often mistakenly identified as small vessels like fishing trawlers when first visually sighted.

U.S. submarines, like other U.S. warships, are equipped with Automatic Identification System (“AIS”), but are not required under U.S. law to use it. All U.S. Navy ships, however, are now instructed to activate AIS in designated areas, with the specific implementation subject to command discretion based on operational needs and security considerations.&nbsp;

U.S. submarines will use bridge-to-bridge communication and will comply with the Bridge-to-Bridge Radiotelephone Act. In sharing information about its course, speed, and intended collision avoidance maneuvers with nearby vessels, a U.S. submarine may in some circumstances, for security purposes, only identify itself as a “U.S. Navy warship,” or “U.S. Navy unit.”&nbsp;

Weapons Firing Exercises: The United States has established submarine operating areas for torpedo and missile practice firing exercises, the boundary limits and designations of which are shown on charts in magenta or purple lines. Vessels should proceed with caution in designated areas. There is a real danger that a well-intentioned ship or boat, unaware of these operations, might turn in the submarine’s direction to investigate a submarine periscope. During torpedo practice firing, all vessels are cautioned to keep well clear of naval target vessels flying a large red flag.

Regulated Navigation Areas, Safety Zones, Security Zones, and Military Craft

Under U.S. law, 33 U.S.C. §91, the Secretary of Homeland Security is empowered to control the anchorage and movement of any vessel in the navigable waters of the United States to ensure the safety or security of any United States naval vessel in those waters.

Federal regulations governing Regulated Navigation Areas, Safety Zones, and Security Zones outlined in 33 CFR Part 165 establish different types of limited or controlled access areas to protect U.S. Coast Guard vessels and U.S. Navy and Coast Guard facilities.

U.S. naval vessels are protected by a system of rules and regulations, primarily through the Naval Vessel Protection Zone (“NVPZ”) and the implementation of Homeland Security regulations. This includes establishing restricted zones around naval vessels, requiring commercial and recreational vessels to slow down and maintain minimum speed, and ensuring commercial and recreational vessels do not enter the NVPZ within certain distances without authorization to protect naval vessels from potential threats and maintain the security of U.S. waters.

The NVPZ regulations prohibit any commercial or recreational vessels from coming within 100 yards of the NVPZ and require that any such vessels slow to minimum speed within 500 yards of any large U.S. naval vessel (over 100 feet in length). Commercial or recreational vessels that need to pass within 100 yards of a large U.S. naval vessel within an NVPZ to operate safely in a navigable channel must contact the Coast Guard, the senior naval officer present in command, or the official patrol on VHF Channel 16. Violating the NVPZ Regulations is a felony offense, punishable by up to six years in prison and/or a $250,000 fine.&nbsp;

Coast Guard vessels are protected by “Security Zones” established by the U.S. Coast Guard Captain of the Port (“COTP”). For example, in the Long Island Sound COTP Zone, a Security Zone has been established for a 100-yard radius of any anchored U.S. Coast Guard vessel. Security Zones also have been established in the vicinity of the U.S. Coast Guard Academy and the Naval Submarine Base at Groton, Connecticut. A “Restricted Area” also has been established in the vicinity of the Groton Submarine Base that requires all vessels to leave the Restricted Area when notified by submarine base personnel that such use will interfere with submarine maneuvering, operations, or security.

U.S. Coast Guard-established Security Zones are closed to all vessel traffic, except as may be permitted by the COTP or a designated representative. Commercial or recreational vessel operators given permission to enter or operate in the Security Zones must comply with all directions given to them by the COTP or the designated representative. Commercial or recreational vessel operators desiring to enter or operate within the Security Zones must request permission to do so by contacting the COTP by telephone or via VHF Channel 16.&nbsp;

Both the U.S. Navy and the U.S. Coast Guard are authorized to use deadly force to protect themselves within the NVPZ, Security Zones, and in other security situations.&nbsp;

We hope this article can be used as a circulated fleet message for any commercial traffic operating in the vicinity of military vessels to provide further context about standard military operations in the United States.&nbsp;

This article is one in a series of articles written for Blank Rome’s <a href="/news-and-events/mainbrace-june-2025/" id="25921">MAINBRACE: June 2025</a> edition.

Navigating Safely: Tips for Commercial and Recreational Vessels Operating near Military Craft

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Navigating Safely: Tips for Commercial and Recreational Vessels Operating near Military Craft

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