My OH has been using an Archimedes bath lift very successfully for some time but recently the fixed seat has become a problem because he can no longer lift his legs and turn himself to put his legs in the bath. Archimedes do not make a turning seat. I am guessing that he is not the only person with this difficulty and so you might be interested in our solution.
I`ve bought a non-stick oven liner from Lakeland plastics for £9.99. I cut it roughly to size and now I can easily turn him as necessary. Just a word of warning, we do have a support rail so he can`t turn so easily he slips off the seat into the bath.