@alir83 Although that wording may sorta work sometimes, that wording is not what I see in my copy of COLREGS, and is no substitute for the correct rule.. Part 83.34 of Rule 34 "Maneuvering and Warning Signals" has the text used in this video and no reference to 'altering course'. Here the actual rule is verbatim: "83.34 (a) When power-driven vessels are in sight of one another and meeting or crossing at a distance within half a mile of each other, each vessel underway, when maneuvering as authorized or required by these Rules: (i) Shall indicate that maneuver by the following signals on her whistle: (1) One short blast to mean “I intend to leave you on my port side”; (2) Two short blasts to mean “I intend to leave you on my starboard side”; and (3) Three short blasts to mean “I am operating astern propulsion”. (ii) Upon hearing the one or two blast signal of the other shall, if in agreement, sound the same whistle signal and take the steps necessary to effect a safe passing. If, however, from any cause, the vessel doubts the safety of the proposed maneuver, she shall sound the danger signal specified in paragraph (d) of this Rule and each vessel shall take appropriate precautionary action until a safe passing agreement is made."

@@SailFanatics I wonder if it has something to do with the source of information. The best PDF of the IMO COLREGs I can find online is here cil.nus.edu.sg/wp-content/uploads/2019/02/1972-Convention-on-Regulations-for-Preventing-Collisions-at-Sea.pdf. See rule 34 on p21. Other sources, including RYA publications, confirm the wording and the directions. I think, however, we are saying the same thing, just explaining it differently. If you were to leave someone on your port side, you would inevitably be altering your course to starboard and vice versa.

@@SailFanatics I suppose the wording depends on your source. The best PDF version of the IMO COLREGs I could find online is here cil.nus.edu.sg/wp-content/uploads/2019/02/1972-Convention-on-Regulations-for-Preventing-Collisions-at-Sea.pdf. See rule 34 on page 21. The same wording is used in a number of sources including RYA literature. Both copies, however, are saying the same thing, just differently, because if you were leaving on your port side, you would inevitably be altering your course to starboard and vice versa. I have altered my original comment to avoid confusion. Thanks for the discussion and the clarity.

Yes, "prolonged blast" is the correct term. Not trying to be pedantic. There is a CG test question somewhere that makes a point of the term, and that there is no such thing as a "Long Blast"

Jhon, it sounds like you have the idea correct, if you blow one shot blast, you will stay to your right, leaving the other boat to your left (port) side.