There is no on/ off switch for the GRO light. just a battery to plug in or unplug.
@roym said:
There is no on/ off switch for the GRO light. just a battery to plug in or unplug.
Another reason to keep it in the shed. 
Just about any little electric gizmo you buy will fail after a few saltwater excursions. So buy accordingly. If you don’t want to buy high end waterproof, buy many cheaper models. If you buy expensive it too will eventually get condensate inside and fail. (buy, use, replace , repeat) I think there is a country song about that.
Fortunately I dont salt my water. 
@qajaqman said:
Fortunately I dont salt my water.
Naw, salting the roads is bad enough…….
Replace the battery on a warm humid day then get that cold "sweet " lake water on it and you have condensation water inside the case. That causes rust/oxidation on contacts.
This is what I’m testing, because its what I have
Pretty cheap, and works underwater for 2 hours under kitchen conditions. The top pops off and the circuit board comes out so when I come home I can remove the cover along with my hatch covers and it should dry right out. Take the twisty legs off and it will mount nicely with velcro, and a little tape or flex paint will make it direct light only at the compass. The only problem I see is that it will need to be mounted on something to elevate it a little bit, or I wont be able to whack it with my paddle to turn it on. And I don’t know if it will block the compass view. As as, its flush with the front edge of my front hatch, so I cant push the button. But I could also make a little “button-pusher” with a bungee that slips on the end of a paddle.
Now, I only need a compass to test my invention
since gps came available, I’ve used them for navigation pretty much exclusively (though always with compass packed away - accessible).
Before gps, when navigating at night (often), I used a little handheld - tritium compass - close enough to read (under bungy).
To each their own I guess. I never bring gps when I paddle or hike (takes the fun out of it for me), and wouldnt want to rely on handhed compass if I have to concentrate on keeping upright. Certainy good to have one for backup though.