International Tug of Opportunity 
System (ITOS)

There are approximately 100 tugs participating in ITOS.

What is ITOS?

The International Tug of Opportunity System (ITOS) accurately tracks existing tugs in the Puget Sound area, using Automatic Identification System (AIS) transponder technology, so they may be quickly identified to respond to a vessel in distress due to a loss of power or steering. It was voluntarily sponsored and developed by an international industry coalition with the goal of providing U.S. and Canadian Coast Guard first responders with a tool to improve marine transportation safety. The ITOS coverage area includes the entrance to and Strait of Juan de Fuca, waters around the San Juan Islands, Puget Sound, and adjacent waters.

ITOS starts in 1997

On May 1, 1997, the ITOS Coalition began the assessment of a $50 arrival fee for all vessels greater than 300 gross tons transiting the Strait of Juan de Fuca. This fee paid for the initial implementation of the ITOS program including purchase of computer systems located at the Marine Exchange (MAREX), as well as the U.S. and Canadian Vessel Traffic Service centers. The fee also paid for the installation of VHF radio transponders for over 100 tugboats. The first transponder was installed in October 1997.

Benefit of identification

ITOS enables Coast Guard first responders with another tool to quickly identify the location and capabilities of tugs in the vicinity of a stricken vessel that may be able to render assistance. The potentially quicker response time afforded by ITOS

is aimed at reducing the risk of a vessel drift grounding in area waters.

Geographic Coverage provided by ITOS

The U.S. Coast Guard published in August 1999 a report that looked at system coverage. The analysis used ITOS tug data and VTS vessel data to investigate the likelihood of a tug being located in the vicinity of a vessel for each location throughout the entire Puget Sound region. The report did not address tug capability. Across the entire waterway the probability that a tug would be available was approximately 71%. In the waters of the western half of the Strait and offshore approaches, ITOS will likely provide a tug approximately 42% of the time.

ITOS Net Cost Effectiveness

In November 1999, a regulatory assessment, focused on the risk due to underway accidents leading to oil spills, was completed. This assessment evaluated 8 alternatives for mitigating oil spillage in the Puget Sound region; one of which was ITOS. This report found:

  • Due in large part to its relatively low cost, ITOS was the most cost-effective alternate.
  • The pollution averted was significantly less than most of the other alternatives.

Other Sources of Information:

An analysis of the geographic coverage provided by ITOS from November 98 to May 99 can be found on the internet at

The Thirteenth Coast Guard District Public Affairs Office (dep) created this page on December 27, 1999 and last modified it June 26, 2002. This page may be reproduced locally. If any changes are needed please notify D13 (dep) at 206.220.7237. More Coast Guard information can be accessed at and a complete listing of these fact sheets can be found at