Good thread bobw. To get things going let me lay out a few of my inherent prejudgises if that is a word. Being a duster pilot I realize that I deal with a low-level-perspective that is innate and natural to me due to my profession. So I realize some folks look at my posts regarding low level thermalling as being nonserious or nonchalant of the risks involved. Believe me, that surely is not my attitude. As a cfi-g I understand and have seen the results of the biggest killer/injurer of pilots still to fhis day, namely stall/spin. Realize however, I was a glider pilot for many years before I got involved in dusting. Prior to dusting I thermalled just as low as I do now. What I was doing was done out of general knowledge, "fly faster, be totally focussed in whats happening etc". The only difference is now I have many thousands of hours of optically gauging the distances and sensations encountered when flying low.

So all that being presented as a preamble, let me say that the issue is proper airmanship, a proper turn is a proper turn irregardless of the altitude.. Doing crappy ignorant turns at altitude may be non life theeatening but they will kill you with no altitude. Similarly, doing proper informed turns at low altitude is not dangerous. Gusty conditions need to be acknowledged, and a reachable safe landing place needs to be present. Given those two considerations, turning while low is not inherently unsafe, while crappy turns at altitude may actually kill someone, like the guy who stalled out and spun past me while flying at 4k feet in a gaggle.

Lets get practical. The low saves I have made, and being a xc 1-26 driver, I've made many, are all made 1. With a landing spot already located. 2. With extra airspeed. I keep my bird moving and if I cant thermal within the lift at that speed, then ok I'm gonna land. This gives me a margin for error with the gustiness of low level turbulance and the nasty bottom of a thermal. These are the very same factors we have in mind while spraying.

As to an absolute minimum height, my minimums are dependent on terrain, turbulance, and distance from my previously chosen landing field. The lowest I have thermalled was at 150 ft on a relatively calm day over a 180 acre level wonderfull field. I felt like the asw12 pilot previously mentioned, i could set my bird down anywhere I needed safely in that field if needed, and I was flying well well well above stall speed.

That should get the ball rolling.
Dan