Regal 3760 Owner's Manual page 49

Chapter 3
NAVIGATION RULES
An overtaking boat is burdened, and is not the priveleged craft, even
though it approaches the danger zone of the overtaken boat.
The overtaking boat first signals with a single blast if that boat desires to
pass on the starboard side of the boat ahead, or a double blast if passing
to port. The overtaken craft responds with the same signal if safe, or
with the danger signal (5 short blasts or more) if unsafe. The boat
overtaking must not pass unless the appropriate signals are sounded.
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