Boat behind you

WaterLine photo by Capt. Josh Olive

When you’re out on the water, it pays to keep your head on a swivel. While a boat that’s going to pass you is supposed to let you know, the chances of that are pretty small.

Based on the questions I have been receiving via email and what I routinely observe while out on the water, I believe a column on what sound signals are required prior to overtaking (passing) another vessel while operating upon inland waterways is warranted. The information in this column will educate a few readers and shock others. However, the vast majority will just shrug their shoulders and continue violating the USCG Navigational Rules of the Road (NAVRULES).

Before discussing sound signals, it’s probably a good idea that I refresh your memory. Or, if you find you have no knowledge on this subject, locate a comprehensive boating education school and learn what collision regulations are (COLREGS) and why we have them. You should also find out what a COLREGS demarcation line is, and what the term “inland” waterway means with regards to sounding required signals. Without being brilliant on the basics of the NAVRULES, comprehending what signal to sound or what you’re hearing while formulating a decision to keep your vessel (and others on the water) safe will not be possible.

After decades of collisions at sea that took the lives of countless numbers of mariners, the Inter-Governmental Maritime Consultative Organization, which has since been renamed the International Maritime Organization (IMO), was established. These organizations helped develop our current NAVRULES in use today. They were agreed upon and formalized in the Convention on the International Regulations for Preventing Collisions at Sea in 1972, and became effective on July 15, 1977.

The NAVRULES were developed to aid mariners in safe navigation and help prevent collisions, just as driving laws aid vehicles in safe driving. Both professional and recreational mariners alike are required to be proficient in the NAVRULES and must understand that they are legally binding. Read that again. No, they’re not optional. Yes, they do apply to you.

In an overtaking situation, you must understand what signal to sound, and whether that signal requires a response from the vessel you are attempting to pass. The COLREGS are separated into two locations, international waters and inland waters. In international waters (such as the Gulf of Mexico), most maneuvering sound signals are conducted as a courtesy to the other vessel, and you’ve likely already made the maneuver.

In inland waters (such as Charlotte Harbor), a maneuvering signal to overtake another vessel is sounded as an intention and must be answered by the other vessel. The line separating these locations is called the COLREGS Demarcation Line. This dashed magenta line found on most NOAA navigation charts separate waters upon which mariners shall comply with either the inland or international NAVRULES.

Now that we’ve reviewed the basics, let’s discuss the required signals and responses for overtaking a vessel in the most restrictive area — inland waters.

When two power-driven vessels are in sight of one another and the vessel astern (behind the other vessel) intends to overtake the other, she shall indicate her intention by initiating the following signals on her whistle: One short blast to mean “I intend to overtake you on your starboard side” or two short blasts to mean “I intend to overtake you on your port side.” The vessel about to be overtaken shall indicate her agreement by sounding the same signal.

If she is in doubt or disagrees with the maneuver, or fails to understand the intentions or actions of the other vessel, or is in doubt whether sufficient action is being taken by the other vessel to avoid a collision, the vessel in doubt shall immediately indicate such doubt by sounding at least five short and rapid blasts on the whistle (a short blast is about one second in duration). If both vessels reach an agreement by using a VHF radio, they are not obliged to sound the whistle signals prescribed by this rule.

No need to rub your eyes; you read the above requirements correctly. Sounding a signal in inland waters prior to overtaking a vessel, then waiting for a same signal response or hearing five rapid short blasts of the ship’s whistle, is not an option — it’s the law.

Now, have you ever heard a vessel sound a maneuvering signal prior to overtaking a vessel, or wait for a reply before doing so? Neither have I.

I routinely observe oblivious boat operators looking directly ahead while sipping on an adult beverage and of course periodically checking their cell phones. Prior to overtaking a vessel, I normally sound the appropriate signal to “wake up” the situationally unaware boater. The responses to my signal include startled and confused looks, rude finger gestures, and hands thrown in the air. And then there’s my favorite: The other operator remains unaware to the entire situation and never even turns around.

Stay safe out there and make good decisions. The safety of your vessel and those lives you are charged with keeping safe are counting on you.

Capt. Jack R. Sanzalone is a 30-year submarine veteran and licensed USCG Master Captain and assessor with 40 years of experience. He is the owner of Boat Tutors and teaches both basic and advanced boating education. Contact Capt. Jack at or visit his website,

Capt. Jack R. Sanzalone is a 30-year submarine veteran and licensed USCG Master Captain and assessor with 40 years of experience. He is the owner of Boat Tutors and teaches both basic and advanced boating education. Contact Capt. Jack at or visit his website,


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