1 · What VTS is

A Vessel Traffic Service is shore-based monitoring of harbor traffic — typically a USCG operations center using shore radar, AIS, VHF radio, and (in modern systems) CCTV to track and direct vessel movements in busy ports and approaches. The role is closer to "harbor air-traffic control" than law enforcement: VTS controllers help vessels avoid each other and groundings, broadcast traffic and weather updates, and in some areas issue traffic management directions vessels are required to follow.

VTS exists under the authority of the Ports and Waterways Safety Act of 1972 and (for the St. Lawrence Seaway) the St. Lawrence Seaway Act. Pub 1310 Ch.5 is brief by design — VTS implementation is delegated to local Coast Guard sectors and varies by port.

2 · Five major US VTS zones

The five primary services Pub 1310 enumerates:

• VTS New York — covers the harbor, approaches, and East River/Long Island Sound. One of the busiest in the US.
• VTS San Francisco — Bay, approaches, and the Golden Gate. Strong currents and heavy fog make this one operationally demanding.
• VTS Puget Sound — Strait of Juan de Fuca, Puget Sound, Lake Washington Ship Canal. Joint operation with Canadian counterparts (Vancouver Traffic).
• VTS Houston/Galveston — the Houston Ship Channel and Galveston Bay. Deep-draft tanker traffic.
• VTS Prince William Sound — established post-Exxon Valdez; tanker escort and tracking through Valdez Narrows.

Less sophisticated services exist in other US ports (Sault Ste. Marie, Berwick Bay, Louisville, others) — typically passive in nature: traffic separation schemes, regulated navigation areas, voluntary reporting. Outside the US, virtually every major commercial port has some form of VTS; the IMO publishes Resolution A.857(20) Guidelines for Vessel Traffic Services as the international standard.

3 · How a VTS interacts with you

• VHF reporting points. Vessels > some size threshold (varies by port; typically 40m or 300 GT, or any vessel carrying passengers/oil/hazmat) report by radio when they cross designated waypoints. VTS uses the reports + their own radar/AIS to maintain a real-time picture.
• Information broadcasts. VTS broadcasts on a designated VHF channel (varies; e.g. NY VTS uses Ch.12 and 14): traffic in the area, weather, sea state, navigational hazards, bridge openings, channel closures.
• Advisory or directive. Most US VTS are advisory: they tell you what's happening but you make the decisions. Some (Puget Sound, Houston/Galveston) can issue directives — orders that legally bind the vessel. Outside the US, many European VTS are similarly directive.
• Mandatory participation. If you're in a Vessel Traffic Service Area (VTSA), participation in the local VTS is mandatory for vessels above the size threshold. Below the threshold (most cruising sailboats), participation is usually voluntary but recommended.

4 · Joining a VTS as a small craft

Cruisers in a VTS-monitored area should:

1. Read the local user manual. Each VTS publishes a user manual covering the area boundaries, reporting points, VHF channels, and traffic separation scheme. Available from the local USCG sector or online via Navigation Center (navcen.uscg.gov).
2. Monitor the working VHF channel while in the area, even if you're below the mandatory-reporting threshold. Knowing what the big traffic is doing keeps you out of its way.
3. Call them if you're confused. "VTS Sector One, this is sailing vessel Melody, 38 feet, transiting east abeam Buoy XX, can you confirm any traffic in my vicinity?" — completely fine, often appreciated. They have the picture; you don't.
4. Don't clog the channel. The channel exists for traffic management. Routine ship-to-ship chat goes on Ch.13 (US bridge-to-bridge) or Ch.16 → working channel.

5 · How VTS relates to your radar

• Their radar > yours, in their area. VTS shore radar covers the harbor with multiple sites, each with antennas higher and more powerful than yours. They see things you can't (the ship 5 nm behind the Bay Bridge, the tug coming around the headland).
• You're on their radar before you see them on yours. Doesn't matter who calls who — VTS picks you up at the seaward boundary and tracks you through. The right mental model is "I'm being watched"; this is comforting in fog.
• If your radar dies, VTS can help. Call them, tell them you've lost radar, and they'll vector you and warn you of traffic. Some areas have shore-based "talker" services for exactly this case.
• AIS and VTS are complementary. Modern VTS centers integrate AIS data with their radar; if you transmit AIS your name appears on their screen. Class B AIS is a cheap way to make sure they know who the small target is.

Practical takeaways

• Look up the local VTS user manual before you arrive. Each port is different.
• Monitor the working VHF channel in any major US harbor — even unreported.
• Class B AIS is the cheapest single radar/safety upgrade for offshore-cruising small craft entering busy ports.
• Don't rely on "the big ship will see me on radar." Your fiberglass hull may be a marginal target for them; your AIS transponder is unambiguous.

References