Update ... update ... update ...
Our current position is on the River Thames at Osney Lock in Oxford, heading for Beale Park and the IWA Festival. We're a long way behind schedule. Read on.
Er, yes. The prop fell off. We were on a stretch of the River Thames with a reasonable amount of flow. Jan was steering. I was sweeping up dust and bits on the rear deck when somehow I managed to shake the dustpan overboard along with the dust. Leave it, said Jan, but I wanted at least to try to get it back. After all, I'd managed to retrieve the lost boat hook. So I put the gearbox into astern ... CLONK! No drive! Oh, no, I thought, those bolts have sheared off. And we were without steering, passing a line of moored plastic boats. The first thing to do was to avoid crunching into them, and try to get secured. The plastic boats were moored outside a caravan park, and we began gently to drift backwards towards them. I tried to push the bow round with the longest shaft on the boat, but the water was too deep, and there was no purchase among the bushes opposite the boats. There was a small unoccupied jetty. Could we get there? Just at that moment a woman from the caravan site called out that she could take a rope. I had one chance to throw the bow rope to her; she had one chance to catch it. Yes! The throw was good, and so was her catch. Hanging on to almost the very end of the rope she managed to stop our drift downstream, and Jan fended off from the plastics. Our saviour, Hilary, tied the rope to a post. Willow was against the jetty, sticking out a bit, but not touching any other boats. That was the only unoccupied spot for some distance.
With the boat now secure, I lifted the deck board to have a look in the engine 'ole. Strange - the bolts were there, still in place. OK, it must be something in the weed hatch. A moment later I was in there, and, oops, it wasn't something in the weed hatch. It was NOTHING in the weed hatch, at least, nothing feeling like a propeller. AARGH! The prop's come off!! The loud clonk was the sound of it bashing the skeg on its way to the bottom of the river.
Why it came off I don't know, except that the securing nut must have come off first.
More later, with photos.