I have a fairly reliable on-side and off-side roll. I am an athletic 190lb, 5’11” male. In big, highly-aerated white water the infrequent times I had to swim, my head was underwater 50% of the time. My existing PFDs average about 16.5 lbs of floatation and they are very easy to roll with. They provide adequate floatation in flat water and mild white water. For big white water only, I am considering upgrading my PFD to either a 22 lb floatation Type V (rescue) model or a 26 lb Type V (rescue) model. How will either these high buoyancy PFDs affect rolling? Intuitively, it seems that I would probably end up on my side as apposed to under the boat and have to roll up from that position.
In really highly aerated water,
differences in PFD flotation are going to make less difference.
However, I recommend you also check that your PFD is staying down where it belongs.
Finally, high flotation PFDs may interfere with rolling by affecting body position more (by constriction and interference with movement) and/or by trapping larger amounts of water in the jacket (weighing your body down as you emerge from the water surface) and/or by increased hydrodynamic resistance to the motion of your body through the water.
The latter two effects are greater if you are using an old-style PFD that has multiple foam segments. My old Wildwater Designs Walbridge PFD, made from a kit, with 30 pounds flotation, was terrific once I was swimming, but not good for rolling. My newer Stohlquist Max, 22 lbs flotation, is made of close-fitting foam slabs, and it rolls better. However, my Lotus Sherman rolls better than the Stohlquist Max.
If we swim in very turbulent, aerated water, we just have to count our blessings while waiting to reach the surface for the next breath.