Mel, thanks. We want something which will hold it whenever someone takes their hand off the crank handle; if they let go it runs away as described above. The U bolt idea is good though for holding it; we use a rope at present which does something similar. But thank you.
Paul, that is a good idea. Our shutter is pretty heavy so it may need to be a chunky battery. How do you go about charging up that battery? We’d need someone to remember to connect it to the charging circuit unless we always parked the dome in azimuth in the same position and set up a positive and negative contacts at specific locations on the dome and the on the rim of the supporting wall. But an interesting idea.
James