We have always had Dive Alert Network. Thought I was going to use them on a dive trip when getting off a beached boat. A wave hit the boat throwing me towards the engines. I had a new camera housing that I protected and hit the engine with my fore. head. Splitting my head. I told them if I can get the bleeding stopped I would make the next dive. A lady came up to me said she, "was a nurse and could see my skull". Needless to say I didn't make the next dive.