Yeah I am a little confused on this. Is the tri- a R/G on top of a white all round?
That would be usuall. And you would have the white all round on a seperate controlled circuit so as you can switch it off while underway. A seperate stern white light is then required.
As for photo-cell. Well if you really have to save the power, then it is a way of doing it. The photo
cell doesn't have to go all the way to the mast head
. It can stay down lower so as it saves additional wiring
going up the mast
. The cell needs to be in a protected box with a clear lid for light of course.