Re: Thanks, and another question
Why do most of the highest-powered lights have the switch mounted on the end cap? This seems very clumsy to me, an almost total non-starter for my intended use, and I would think for most people who really need a handheld light. I need to be able to use the light one-handed so my other hand is available to operate other equipment and/or keep myself on the boat and out of the water!
I"ve spent good chunk of the last two years trying to come up with the perfect boating light. If you search this site under "boating" you'll find a whole bunch of threads (many from me) that discuss.
Yes - narrow beam is best. Especially on a sailboat where you don't want light reflecting off deck or sails.
The ultimate lights for this are "asperical" lights -- these have a special domed lense that makes the light act like a laser - single straight beam with no spill. I've resisted this as it seems a bit extreme. You want a little spill.
If I were you - Consider lights with XPG type emitters (I think the most modern versions are XPG2). The absolute lumen numbers will be lower than XML lights but the beam is much more narrow and focussed and generaly travels farther. But it still has some spill. A good "Throwy" XML light is probably ok too. This means it has a large and long head creating a narrower, farther throwing beam.
I, too, have been searching for a good single handed light. Hard to find. There's more out now than there used to be, but still many have a tail clicker, and further adjustments are made by buttons, head twists, etc. Drives me nuts.
Lastly - the 2 other key things you need is pocket-ablity and a low -low. Like less than 5 lumens - around 1 is probably best. AND, you need to be able to access this low directly from OFF so you don't fry your eyes. Finding a light with all these features has proven impossible to me so far.
Here are some I"ve been considering:
-Thrunite TN31 - (someone referred to this above) powerfull, low low, one-handed, but a bit heavy and expensive. Hits many of my requirements but looks like would be hard to fit in pocket.
-NItecore SRT 6 or 7. This hits the most boxes for me (but i'm still not getting it). ONe handed operation with a twisting control ring that can go from 1 to 800 +lumens. good thrower. You can adjust ring before you turn on, so you know what your getting. This has an XML emitter (a bitter wider beam) but i'll bet it would serve you fine. Its small enough to fit in a pocket if needed quickly.
-Skilhunt Defier S2 -just reviewed on this site. Has good throw (also an xml) and almost a one-hander.
-Eageltac D25X(something)- again, strong beam, able to come on in low,low and almost one-handable
Armytek - makes some really powerfull XPG, pocketable lights but they're all two handed twisting UI kind of lights.
I'll probably think of more later. Good luck.