I do not use any if diving my local waters. Here off Catalina you generally exceed recreational diving limits pretty close to shore so you are usually close to the boat or shore when you surface. When I travel, I do carry a safety sausage but have not had to deploy it yet. I thought I came close on one dive in Palau (Ulong Channel with a swift current) when I got separated from the group due to a fin coming loose, but I ended up at the same spot the other divers and boat were at the end.