Oh dear.

I stopped the engine and dropped anchor, and lifted the prop out of the
water, only to find that there was no longer drive getting from the engine
to the prop.

I don't know your particular engine but whenever I've done this or
heard of someone else doing it, it has always been the drive pin.
This, as I recall, is designed to fail before any really expensive
bits are damaged.

Hope this is what's happened in your case.

Lindsay