The biggest risk I take diving in south Florida is the possibility of getting run over by a boat. It's something that's always on my mind. I will not beach dive on weekends and holidays. On other days when there's less boat traffic I still never let down my guard. Being visible with a dive flag offers no assurance, sometimes I think that on the contrary it attracts boaters. The only defense I found is to always be aware of approaching boats. My first sense to detect a boat is hearing, that's one reason I will not wear a hood.
Once I detect the sound of a boat motor I immediately surface to locate the boat, then watch to determine its direction. Often the boats are obviously not on a collision course with me, I still watch until I'm sure they're past the point of changing their trajectory towards me. After that the diminishing sound of the motors is further assurance and I continue diving. Sometimes I take more time to ascertain the boat's trajectory as it's passing closer to me. At those times I will stay and watch until I can see the boat moving away rather than getting closer.
It's never yet happened to me that the boat is getting closer and closer and at some point I realize it's heading directly towards me. But I've rehearsed this scenario in my head many times and this is how I imagine it will go down. At the moment I become sure that the boat is going to run me over, I start calculating how much time I have before it reaches me, this depends obviously on the boat's speed. If I'm towing a float that's tied to my gun I'll let go of the gun. My thought is to wait until the last possible moment to have enough time to break the surface and dive deep enough to get under the boat, but not so long before the boat gets to me that I will need to surface to breath just as it passes overhead.
Not having enough breath hold to stay down until the boat passes is the most serious point of concern to me, because I know that when the time comes I will choose to dive sooner rather than later. Once I'm down there waiting I imagine having some serious doubts. In between the time I dove and reached a safe depth the boat may have seen my flag and reduced its speed a little, then it will take longer to pass. Once I'm down there the boat could've altered course and passed to one side and I didn't know. I could be down there still waiting for it to pass. This point has always been of the most concern and uncertainty for me, and I imagine that in that situation I will hold my breath for as long as I possibly can, unless I see the boat pass of course.
So surviving this situation depends on:
1. Being in the right state of mind to perceive an approaching boat.
2. Having the will power to stop diving and watch the boat every time.
3. Correctly ascertaining the boat's trajectory.
4. Timing your dive early enough to get under the boat but not so early that you'll run out of air before it passes.
5. Hold your breath long enough for the boat to pass.
Anyways like I said this has never happened yet so I can't say I'm %100 ready to deal with the situation. But this is exactly what happened to Steven recently, and his kayak did get hit by a big fast boat. After knowing that he's OK and finding out he did what I plan to do, I was very interested in a detailed description of what he felt and how he timed his dive to avoid the boat. So I started this thread as an intro to his story.