Any motion light can work for this. The idea is to light up intruders in the cockpit, or, as you arrive back at the boat late, to light your way. I find it very nice to have as I pull up to the back of the boat in the dinghy in the pitch dark. We do have a light in the cockpit area, but many times, happy hour has turned into many happy hours, and we arrive well after dark and therefore we’ve not left a light on.
I like it for deterring anyone trying to sneak about too. If they walk onto the back of the boat at night, they’ll get a bright light right in the eyes, smile!
For the cost and convenience, I like having one of these aboard. The one I use is a 27 bulb LED that is battery operated. It’s very bright, and easy to hang or tie around the back of the boat. I found it on Ebay and Amazon.