I have one of these with a diffused lens mounted at the top of my mast on the front pointed straight down.
http://www.rigidindustries.com/Marine-Series-Dually-LED-Light-p/marine-dually-fl.htm
I picked it up to do some testing with it, cause I'm one of their dealers and like to know what I'm selling. It's a pretty spendy light, but just one lights up the entire boat and the immediate surrounding area very well, and draws less than the incandescent anchor light right below it. I use it all the time for messing with the anchor, docking and getting onto the trailer at night, and just for general light on deck when I'm hanging out with friends.