alan...
You are not "shining" it into anyones eyes...done right it is seen as a "flash", or "Sweeping Movement of Light" and draws attention. It is much like a reflection of a mirror in the sunlight...or maybe the flash of a camera from across a stadium...Or it can be seen as a "swweping of light", like a cars headlights sweeping through the window at your darkened home some evening... you see it,but it doesn't blind you...the flash of the light attracts the eyes.You instinctively look for the source of the light unless your mind can say 'that was a car driving by'...Try it with a buddy boat in a dark anchorage even...you'll see what I mean...It works really well...and is one of the only active ways to try to attract attention, without flairs...You don't even have to use a hand held spot with alot of power... You can normally make your boat noticed with a regular flashlight, depending on conditions, and the other vessel will normally acknowledge...The fact of the matter though is if you are afraid of someone not seeing you, once you've drawn thier attention, you have accomplished your goal, even if you were to inhibit thier night vision temporarily, they will recover from it quickly and will have seen you. Lighting up your boat will not normally get you seen any better,because often the other vessels "watch" isn't watching,especially if it is of the size that really has you concerned.Lighting up your own boat will most certainly blind you,plus confuse your nav lights character... Putting lights on all over your boat is not the time honored method for a couple reasons...The lights easily get mixed up with background lights on shore, if coastal cruising.., and until most recently,off shore lighting up your boat wasn't even an option...Skippers used kero-lamps for nav lights that weren't to bright,and the sweeping of a hand held flashlight was very common...even today alot of boats(sail) can't afford the constant power drain unless motoring...For many,lighting up like a disco ball isn't even an option...Lin & Larry Pardey, Eric Hiscock, Donald Street, and I am sure others too, talk about this method in thier books,I didn't come up with it on my own... You'll notice these are all cruisers as am I...Normally when I want someone to see me,I am hundreds of miles off shore, and am trying to get a tanker or frieghter to see me, so they'll listen on the radio for me...(I like to get updated weather from them, sometimes check my position against what I have etc..)...If the "lookout" on a ship is not really looking out,and most are not when a large vessel is steaming at 25 knots in the middle of nowhere, even if I was to light Faithful up like a baseball park they won't notice it...There not even looking out there, and the don'texpect anything on the VHF,so often have it off or way down in volume...BUT a sweeping of light across their wheel house will make them look up and around, even if they are playing cards...It works..I'm not trying to lead anyone into danger here...I am sure there are very skilled sailors who have never heard of this or,have and disagree..thats fine...I'm just saying it gets you seen if that's your goal, and is a seamanlike method to do so.