Regarding SOUND on a sailboat of less than 12 meters, an AIR HORN is sufficient.

Now we will look at MANEUVERING and WARNING SIGNALS.

If the vessel is POWER DRIVEN, then here are the sounds it must make if insight of another vessel:

*1 SHORT blast means that the vessel is altering its course to STARBOARD.

*2 SHORT blasts means that the vessel is altering its course to PORT.

*3 SHORT blasts means that the vessel is operating astern propulsion.

Hugh Simpson