I was hoping to change the title of this thread to something more generic like scooter diving safety considerations but that option is turned off in this forum. The following really doesn't bear upon DCS issues.
Anyway, I became more acutely aware of a few safety considerations involving scooter diving this weekend. There was no useable wind in the forecast for kitesurfing but appeared to be more or less ideal for diving in SE Florida, light and offshore from the SW. Went to the Spiegel Grove off Key Largo yesterday expecting 100 ft. plus vis. but ended up with something around 30 ft. more or less and 1 to 2 kt. current. The deck of the Grove ranges from around 60 to 70 ft. and there are some significant obstacles/entanglements, derricks, some lines, etc.. The last time I was there, viz. was 80 to 100 ft. with no current. It was about the same the time before that as well with more current. I was looking forward to shooting some interesting video this time around. Got the video (stay tuned for that) but the dive wasn't quite what I expected.
Even with current as long as you can see far enough ahead to avoid being swept into hard objects or entanglements it isn't that bad. Not so easy in this case, once you eventually saw the wreck you sometimes didn't have long to think about what you would do to avoid hitting something. Even if you weren't knocked out, you would likely lose the scooter spinning off into the haze (I was using a sit on top Evolution scooter, your head hits first!). Not a good prospect. Doing a down current turn would really make things interesting if objects were nearby as you would really accelerate. After a short time, the "Vietnam of Scooter Diving" started to come to mind. Not a lot of fun and a bit too hazardous. Stayed shallow on the dives around deck level or less and cut the number short.
I suspect lots of guys on here would be thrilled with that much viz at their normal spots still running too fast with insufficient visibility may translate to most locations. In short if there is strong current and poor visibility I wouldn't recommend scooter free diving. You can do it but the hazards and unease can easily exceed the benefits of doing it. Better luck next time and I will be sure to get a more reliable idea of probable visibility in advance!