Water clarity also has a huge effect on brightness.

A buddies Top Gun has them and when we are on the river compared to the lake there is a big difference.

If I boated in LOTO all the time I might mount them higher then I would for Lake Michigan.

Matt are you saying above the waterline?

A good friend of mine has a LED light company and one thing he does (and me) was to use industrial Velcro and wire them with cig lighter and see how they work in dif places. As far as I know most of them with decent light output require to be under the waterline or at least in the spray for thermal management.

No, but I could see how it come be taken that. Definitely below the waterline. I was referring to the "below the swim platform" as a general area. The person who started this thread always has the area chosen. What he's noodling on is depth and, I think, placement relative to other underwater LEDs.

Great point above on water clarity and how it could affect the mounting height (call it X-dimension if you like) of the lights.