Masts on Motoryachts?

The forward mast on the foredeck that I think you are referring to is called a steaming mast or pole. On some yachts they are fixed structures and on others, they are telescopic or can fold-away or do double duty as a forward deck crane.

You will find these masts on yachts that are 50-meters in length or longer. Once you see that, it is a good indication that the vessel you are looking at is 164 feet or larger. On the top of these forward masts are lights, usually anchor notation lights and the forward navigation lights. If you look carefully, you would see that the forward mast is...always lower than the height of the main mast. They are carrying the white navigation lights so this helps you to distinguish what direction the vessel is travelling in at night... Hope that helps a bit...That is not all to the forward mast, but other people can further explain, I have to run off at the moment...