Boundary Lines in Relation to Documenting Boating Experience

How to Navigate the Boundary Line: Practical Insights

What is the Boundary Line? 

The Boundary Line is an important dividing point between inshore (internal) and offshore waters, and it serves several key legal and operational purposes:

1. Load Line Regulations: The Boundary Line is used to determine load line requirements, which ensure that vessels are properly marked and meet safety standards based on the waters they operate in. This helps maintain the stability and safety of vessels by specifying how deeply they can be loaded depending on the type of waters (inshore vs. offshore).

2. Mariner Licensing: The line is also used to determine whether sea service qualifies for inland or offshore requirements when applying for a USCG (U.S. Coast Guard) license. Sea service within the Boundary Line may count toward inland requirements, while service outside the line may count toward offshore qualifications.

📥 You can download and print the general Boundary Line PDF here. 

The Boundary Line is often confused with the Demarcation Line, but they serve different purposes:

• The Boundary Line relates to load line regulations and sea service qualifications for licensing
• The Demarcation Line divides domestic (Inland Navigating Rules) and international (COLREGs - Convention on the International Regulations for Preventing Collisions at Sea) Rules of the Road

Though these lines serve different purposes, they may overlap at certain locations along the coast. It's crucial to understand their distinctions and their specific applications.

What are the Boundary Line regulations? 

The U.S. Boundary Line is delineated in 46 CFR Part 7.

As a rule, on the Atlantic and Pacific coasts, the Boundary Line generally follows the high water shoreline, extended across the entrances to small bays, inlets, harbors, rivers, the ends of breakwaters or jetties, etc. In most cases, this means that as soon as an outbound vessel crosses seaward of the entrance, it has crossed outside the Boundary Line.

The Boundary Line does not apply to the Great Lakes. Commercial vessels operating on the Great Lakes are required to have a load line when they operate offshore of harbor breakwaters unless specifically exempted by statute or regulation.

There are some significant exceptions to the above general rule, however:

• In the Gulf of Mexico between the Marquesas Keys, FL, and the Rio Grande River mouth, TX, the Boundary Line is located 12 nautical miles offshore. This creates a 12-mile-wide coastwise marine corridor inside of which non-load line vessels may operate. For ease of navigation, this Boundary Line coincides with the "Territorial Sea" boundary marked on nautical charts of the Gulf;
• Also in the Gulf of Mexico along the western coast of Florida, Congress widened the load line-exempted corridor to 15 NM offshore (i.e., 3 NM west of the Territorial Sea boundary shown on charts) between Crystal Bay and Hudson Creek;
• In New England waters, the Boundary Line follows a series of lights and offshore buoys from West Quoddy Head Light (at the U.S./Canadian border) to Race Point Light (at the tip of Cape Cod). Like the Gulf of Mexico, this also creates a coastwise corridor inside of which all vessels may operate without a load line. However, unlike the GoM Boundary Line (which is a constant 12 NM from the coast), the New England Boundary Line does not follow the coastline and, therefore, is an irregular distance offshore.
  
  

📥 You can download and print the Gulf of Mexico - Boundary Line PDF here.

For this reason, operators of non-load line vessels--including fishing vessels that are more than 79 feet in length and that are built on/after July 1, 2013--should especially familiarize themselves with the Boundary Line in New England waters (refer to 46 CFR Parts 7.10 and 7.15). Taking such a vessel outside the Boundary Line constitutes a load line violation;

• And at other points along the U.S. coastlines, there may also be some local gerrymandering of the Boundary Line from the mouths of inlets or jetties out to the sea buoy and back.

Therefore, it is essential to consult 46 CFR Part 7, in conjunction with the appropriate nautical chart, to determine the specific location of the Boundary Line for any particular location.