This inventory of Richard Mitchell, Mariner, of Bristol in February 1748 gives the money due to him for service on board the Dofianne, Dosianne. The second letter o is clear and there is definitely ianne at the end. I can find nothing about such a ship. I wondered if it could be the Defiance spelled wrongly. Either he died aboard or the ship was wrecked in 1747-8. Somebody on Ancestry says he died in Indonesia but has no evidence, he copied it from somebody else's tree!
I would be really grateful if anyone knows about Bristol ships in the mid=18th century or where to find such information.
