Agree, they should produce a stainless steel ring with a protrusion to mount between the tube and tailcap to fit a lanyard.
Or an additional tailcap with lanyard hole.
Fenix PD36R. Heard good things and exactly $99 US
I wouldn’t want a big aluminum flashlight banging around on a boat in rough seas myself, so I am thinking something like the Rayovac 6 AA “indestructible” spot light would be good. This light has a 4.5 Meter drop rating, is 1 Meter submersible and it floats. It runs on 6 AA’s but I would not rely on alkalines that will leak over time but instead use Energizer L91 lithiums which function in extreme temperatures, have a 20 year self life and won’t leak. If you need rechargeables, Eneloops are the way to go. Note that in a pinch this light will run on only 3 AA’s instead of 6.
Another suggestion would be the Streamlight Waypoint. The Waypoint runs on either 4 C cells or on a 12 Volt power cord. The Waypoint throws further than the Rayovac but is not rated as high for impact and water resistance. Instead of alkaline C cells, I would recommend running the Waypoint on AA L91’s in adapters or low self discharge NiMH C’s.
Clove or blakes hitch with stretchy cord … or prussik with 3-4 turns
Any sailor or should know how
Googled clove knot. Works well.
Use 3mm stretch cord from any outdoor store, the stretch cord holds the clove extra tight … just crank on it
And put it on the head size of the handle for more security
Double clove hitch is even more secure
One light ehhh.
I (also) think the Sofirn SP36 could suit the purpose.
Powerful.
Has USB charging.
Can handle a splash of water.
If you get the BLF edition with the Anduril user interface there is an abundance of useful modes. Momentary ‘ON’ being one of them. I’m not a sailor but I imagine that could be useful.
When I am looking for channel markers in the dark I always have a thrower that has virtually no spill so I can see a long way without bouncing light off of the white surfaces of my boat to blind me and reduce my night vision .
Other than that a headlamp is the best for everything else .
I would recommend you go with a Neutral White or Warm White option to reduce glare from the humidity coming off the water. The warmer light will punch through glare better and won’t be as blinding so you can focus better with your eyes at a distance.
It will be harder to find multi cell lights with built in charging.
The Thrunite TN40S looks like an excellent choice for your use with a very good range but still useful spill, but you would have to charge the batteries separately.
For you to better understand how a light will behave, the smaller the LED (XP-G2, XP-G3, XP-L Hi, XHP35, etc) the longer it will throw in the same sized reflector. Larger mid sized LED’s like XM-L2, and especially XHP50 will be able to support more lumens, still offer a little throw, but be quite floody. The larger LED’s like XHP70, or MT-G2 will be able to output the highest lumens, but the beam will be very floody and not offer much range.
Another point to keep in mind is flashlight size relative to the total output in lumens. A small single cell light that says will do upwards of 1500 lumens is only for a very short period of time. If you suspect you need to use a higher output for more than a minute or two, best you go with a bigger flashlight (3-4 x 18650), as they are able to sustain higher outputs longer and cool down faster.
Some lights using large LED’s can still throw a fair distance, but only on their turbo settings which are not sustainable. Keep this in mind when comparing lights. A 1000 lumen light with XP-L HI or XHP35, with be able to sustain a good throwing distance for a fair amount of time. A 6000 lumen XHP70 light with equal throw will only throw for the first minute or so before it steps down substantially.
Pay attention to what kind of driver a flashlight uses. Some of the budget lights aren’t regulated and output will dissipate as the batteries get weaker. I would personally recommend you get a light that is well regulated.
Some good brands to look at are:
Acebeam
Nitecore
Olight
Fenix
Jetbeam
Thrunite
Good luck with your search!
It certainly does and can still tail stand when they’re in use (which is handy if you want to use the diffuser with it - save the ship power!)
And it’s now available in a 5000k tint, which is a nice bonus 
For signaling aircraft and other boats, remember the throw of a light is how far you can see not how far you can be seen. A friend was going to a knoll over 2 miles from my place (we live on a mountain top). I gave him a walkie talkie to call me when he arrived and then shined my Catapult v6 at him. It is rated for 750 meters. He was excitedly impressed at how bright it was. I can actually see things about 400 yards away, but can be seen for miles. But you probably experienced this with buoy lights.