COMDTINST M16500.21A — Aids To Navigation Manual - Seamanship

COMDTINST M16500.21A governs Coast Guard aids to navigation seamanship, including buoy operations, cutter boats, and related safety practices.

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  • Publication number: COMDTINST M16500.21A
  • Title: AIDS TO NAVIGATION MANUAL - SEAMANSHIP
  • Date: 3/2/2012
  • Proponent: CG-751

View COMDTINST M16500.21A on armypubs.army.mil


The publication includes changes to chain-hook use, cutter-boat crew requirements, Chapter 14, and buoy operations from boats. It provides operational guidance for Coast Guard personnel and includes procedures, environmental considerations, and no forms or reports.

Applies to: It is intended to provide operational guidance for Coast Guard personnel and is not intended to nor does it impose legally-binding requirements on any party outside the Coast Guard.

Topics covered

  • Aids to navigation seamanship
  • Chain-hook use
  • Cutter-boat crew requirements
  • Buoy operations from boats
  • ATON evolution safety
  • Operational risk management
  • Personnel protective equipment

Questions and answers

Who must comply with the provisions of the change notice?

All Coast Guard unit commanders, commanding officers, officers-in-charge, deputy/assistant commandants, and chiefs of headquarters staff elements shall comply with the provisions of this Directives Change Notice. (paragraph 2)

Is operational risk management required before ATON evolutions?

ORM is required prior to ATON evolutions and coordinated teamwork is a critical component for the safety of the evolution. (paragraph 6)

What conditions require a reevaluation of risk?

Changing conditions such as: worsening weather conditions, fouled moorings, vessel traffic, an exhausted crew, broken weight handling equipment, inconsistent positioning equipment, are some examples which required a reevaluation of risk. (paragraph 6)

What variations to the standard ATON evolution are authorized for ATON boats without installed weight handling equipment?

No other variations to the standard ATON evolution for ATON boats are authorized. (paragraph 2)

Where should recommendations for improvement be submitted?

Recommendations for improvement shall be submitted to the Office of Cutter Forces (CG-751). (paragraph 1-1)

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