I was certified in FL with one instructor and four students. The other students had done multiple Intro sessions. I had done one in Maui some 20 years previous. We had 3-4 foot seas during the OW dives, so we were rocking around pretty good. I never thought that the ratio was a bit too much, but I can see now how things could have turned out pretty bad if one of us or even the instructor had issues.
Yeah, those conditions I have cancelled. But hypotically, let's say I would teach in such conditions (though I wouldn't). I'd do double the dives and a 1:2 ratio, even if I had full confidence in the students' buoyancy control, the confined water sessions are done in pool like conditions. Swells like that are a huge stress factor for some people. I might do 1:1 for OW1 as there is no limit to the number of dives that the instructor does as then I can evaluate my students with undivided attention with how they are handling the waves.
Again, I also have to manage student's comfort level. Here they get cold if they are not in a dry suit. I do have a 10'x10' tent that I could set up. If I knew that the seas were to be that way and my students didn't want to defer, I would stagger their arrival time so they are not sitting around. There are many things to consider.
And also again, I've cancelled for those kind of conditions. Having students fall over getting in/out of cold water up a steep, rocky slope is not a risk I'm willing to take.
I guess as instructors, you probably have to weigh all those factors (weather, previous experience, surface support, maturity level, etc) when making a call about student/instructor ratios.
It depends. If the instructor teaches for a shop it comes down to teach at max ratio or there's the door. There have been a number of instructors in my area who have been let go as a result of refusing to teach in a manner that they deemed unsafe.
That's one of the problems I have with agencies putting the responsibility on the instructor. If there was an incident, they can always claim that the instructor didn't reduce ratios enough. The shop can say the same thing. It is the instructor who gets thrown under the bus. Instructors are completely expendible as they are easily replaced, no matter how good they are. Only the quality dive centers actually care. Those are not the majority in my region.
The changes PADI made are improvements, but fairly marginal. It is like the significance of new instructor candidates needing to be neutrally buoyant in 2 skills in order to receive a 4 or 5. That's a joke considering the article of moving to neutral buoyancy written by Adsit, Rothschild, Turner, and others was published about 10 years before PADI made that change.
And before people accuse me of PADI bashing, this is factual. And I have the same criticism for all agencies, including my own, that do not require all skills to be neurally buoyant and trimmed. This isn't rocket science. The amount of physics required to understand why we do certain things and how to address changes in pressure are not exactly intellectually challenging.
I do believe that agencies should give guidelines for conditions where reduction in ratios is mandatory. I would expect the counterargument is that they would assume some liability if they were to do so and an incident occurred where the instructor reduced ratios per the agency guidelines. Well, in all likelihood, the ratio would have been higher in most cases if such guidelines didn't exist like they don't exist now.