I tried the red lens that Joe Lyons included with my Princeton Tech light. I find that it really doesn't shed enough light for me to safely unhook fish or tie knots. As long as you're not looking directly into the lens, white light shouldn't affect your night vision.
What I laugh at are the guys who use red lights and then fire up a smoke every 15-20 minutes. The flare from a lighter does more damage to your night vision than the indirect light from a flashlight--especially after the batteries wear down a little
Last week on the Canal, there were two guys fishing the Cape side, mid Canal, right under a white navigation light, using red lenses--wtf was the point of that
