I may be the resident expert on float tube emergencies and I do wear a Sospenders manual inflatable. The first time I was had my feet higher than my head in my float tube, I did remember I had it on and what was required. Being in shallow still water I was able to right myself without activating it. That was a doughnut tube Last years in my Fishcat I found myself upside down tied to my tube by my casting apron. My face never got underwater, I reached for the pull once did not find it immediately stopped the search effort for the pull and resume splashing and clawing for land. The next week I added a larger braided fob to the activation pull. Last year I would have welcomed an automatic activation the first time I am glad I did not have one.

With a doughnut tube the probability of an unintentional activation would seem to be pretty high as you are sitting pretty low in the water. A young friend told me his auto did operate while in his garage during a warm Georgia summer afternoon. Be sure you can find and pull the activation line in an emergency.