There is one important factor with flashlights. It is smart to have it with you home. Have one extra in the boat. I would recommend bringing the main flashlight home. This is to have a better control
of batteries. A SAK, Multi-tool or a knife should always be personal safety equipment in reach all the time. It is the same with a flashlight.
It is nothing to gain by having a low quality flashlight. Today it is possible to get a fair quality one
for a rather low cost. In my LED pages I have discussed the importance of quality, with the circuit and contacts for comfortable use. It is smart to have an IPX standard that at least can take rain, the best is a standard that can take to be under the surface
or completely soaked. The IPX-8 is a very good standard in my opinion. The materials used on the flashlight must be good enough for the sea. Today it is normal to use aluminum alloys/grades that are anodized for protective surface. This is important as well.
It is important that if the flashlight have been soaked or splashed with salt water that you do some maintenance at home.
There is an advantage with a focus possibility on a flashlight. At least it must be a light that can be seen from a good distance.
be used with holding the hand in front of the light or by using the operating button. It is an advantage with a SOS signaling function because this prevents hand fatigue and more comfortable use.