Ken Kochanski wrote:

As we all know, adding ballast to a glider shifts the polar, allowing
higher speeds at better L/D ratios.

What happens when we are pulling, say 1.5 gees, as we thermal. Does
our L/D and sink rate reflect the 1 gee weight ... or the 1.5 gee
'force'.

The 1.5g force shifts the polar. This causes the minimum sink (and
stall and maximum L/D) to be at a higher speed, which is why we fly
faster when thermalling than when flying at minimum sink in level flight.