Human eye works well with yellow (natural light). LED lights emit different frequencies. Although the candle power or whatever it is called is equal or more than normal hot filament light, it is not visible to the human eye. The objective of anchor light is "to be seen". Make sure you use hot filament light or similiar that is visible to human eye.
The human eye is most sensitive to green. Filament lights actually put out a lot of IR that cannot be seen.
However Lumens take into account the eyes sensitivity so you can compare the visability to a humanan observer rather than the total radiation emitted.
LED anchor lights can be much brighter than conventional bulbs (and the good ones are), because there is not a major power consumption problem to overcome.
My LED Owl is much brighter than the masthead anchor light fitted to most boats (and I have 2) It will even illuminate boats anchored close to me.