The base IP 37 from the factory comes with a single Anchor light at the top of the mast.  There is a steaming light at the spreaders on the mast, a bicolor light on the pulpit and a stern light on the transom.   While this meets the minimum SOLAS and US Coast Guard requirements. Navigation lights down low on the water are difficult to see on open water.  To rectify this a Guest tri-color/anchor/strobe combination was placed at the top of the mast replacing this stock anchor light. 

While sailing, the tri-color is used, when motoring in harbor, the navigation lights on the pulpit are used along with the steaming light.  The strobe can only be used for emergency purposes.  The mast head navigation lights are easily visible from 2 miles out, making the boat much more visible to passing freighters and fishing boats.