I have had one on each of the 6 boats I have owned and have had some mounted outside, and some inside the rail. On our current boat
the wife made this fancy storage
pouch after the original life sling one finally succumbed to the UV rays. I am not sure there is a huge difference, at least operationally, as to whether it is in or outside the rail. I have run numerous drills with them, we try to at least once or twice a season, and didnít notice any issues regardless of its mounting position. I do ensure that it is clear of the stays/shrouds/davits/anchors or any other protuberance that might snag or interfere with it during deployment and that the line goes over the rail so that my wife or I can simply open the pouch and toss the sling into the water
as we return to the helm
to encircle and capture the person in water
. I have also attached it with a large snap shackle so if it is necessary to release it for any reason it can be done quickly under load via the snap shackle or the knife mounted on the davit nearby. More info than you asked for I know but my wife accuses me of talking too much. Apparently that carries over to typing as well.