Nautical Sound Signals

-on this page:

• Maneuvering and Warning
• Restricted Visibility

Disclaimer and Copyright

I provide all information on this page on a liability-free basis. Please use at your own risk, and verify anything critical to your boating safety with other authoritative sources. I have collated and condensed this information for my own personal use, from information in Chapman Piloting (59th ed.), the Canadian Collision Regulations 1983, and the U.S. Inland Rules 1999. I do not intend to imply any special knowledge beyond that. I find it useful in my boating, and I hope that you do to. You may wish to modify it for your particular needs. Suggestions always welcome.

Note: this page does not discuss rules of navigation in general - its only topic is Sound Signals. I strongly advise boaters to obtain and study a copy of the Collision Regulations for their jurisdictions.

This Nautical Sound Signals web page is Copyright © 2001-2003 ctLow. Please feel free to copy and distribute it, but only in its entirety and without modification (so including this notice). Thank you. Charles T. Low

Maneuvering and Warning

Restricted Visibility

A short "blast" means a duration of about one second, and a long (or "prolonged") blast lasts four to six seconds.

I describe things more simply on this page than they are stated in the regs. For example, some levels of jurisdiction would say that a certain whistle signal means "I intend to overtake you on your port side," and another might say (regarding overtaking), "I am altering course to port." I call all these "overtaking to port." Using this simplified scheme (for my own personal sanity), I don't need to list the few Canadian modifications regarding the Great Lakes Basin.

The rules also go into more detail than presented here about what kind of vessel may or must sound which signal under what circumstances. This list that I've concocted is more a "recognition" aid.

A small personal peeve: if it is quite clear that two vessels are in no risk of collision and are going to pass free and clear, then a collision situation does not exist, and none of the procedures for collision avoidance are necessary - although I am a firm believer in "maintaining course and speed," without unnecessary changes (if possible), when other vessels in the area might need to know your intentions.

The Collision Regulations make barely any reference to the term "right of way," and I rarely use it when discussing collision avoidance. One vessel is "privileged" (or "stand-on"), and the other is "burdened" (or "give-way"), but both vessels have obligations, and I again refer to the privileged boat maintaining course and speed. I have another article called Privilege and Burden, which deals with this more fully.

The regulations are quite clear that every vessel must keep a proper lookout, using all means available (sight and hearing at a minimum) at all times. You must operate your boat prudently at all times, and the most frequent violation I see is excessive speed in congested waters (or poor visibility) - being the privileged vessel will do you no good if you are in a collision, in terms of damage, injury or legal liability. The so-called "general avoidance principle" can be inferred from the regulations, and states that boaters must always do whatever is required to avoid collision - being the privileged vessel is no excuse if you could have done something.

All respectfully submitted,

Charles T. Low