Rule 34 - Maneuvering and Warning Signals
(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], [apower-driven | each] vessel underway, when maneuvering as authorized or required by these Rules, [ | (i)] shall indicate that maneuver by the following signals on her whistle:
(b) Any vessel may supplement the whistle signals prescribed in Rule 34(a) by light signals[, repeated as appropriate, while the maneuver is being carried out]:
(i) these signals shall have the following significance:
(iii) the light used for this signal shall, if fitted, be an all-round white [or yellow], visible at a minimum range of [5 | 2] miles, [synchronized with the whistle.] and shall comply with the provisions of Annex I to these Regulations.
(c) When in sight of one another [in a narrow channel or fairway]:
(i) a [power-driven] vessel intending to overtake another [power-driven vessel] shall [in compliance with Rule 9 (e)(i)] indicate her intention by the following signals on her whistle:
(e) A vessel nearing a bend or an area of a channel or fairway where other vessels may be obscured by an intervening obstruction shall sound one prolonged blast. Such signal shall be answered with a prolonged blast by any approaching vessel that may be within hearing around the bend or behind the intervening obstruction.
(f) If whistles are fitted on a vessel at a distance apart of more than 100 meters, one whistle only shall be used for giving maneuvering and warning signals.
(g) When a power-driven vessel is leaving a dock or berth, she shall sound one prolonged blast.
(h) A vessel that reaches agreement with another vessel in a head-on, crossing, or overtaking situation, as for example, by using the radiotelephone as prescribed by the Vessel Bridge-to-Bridge Radiotelephone Act (85 Stat. 164; 33 U.S.C. 1201 et seq.), is not obliged to sound the whistle signals prescribed by this Rule, but may do so. If agreement is not reached, then whistle signals shall be exchanged in a timely manner and shall prevail.
This is allot of information, you just have to take it slow and make sure you understand. Couple of important points: