It's maybe not going to be as easy hitching a lift on a passing cargo ship as I thought. Not many pass one of the most remote inhabited islands in the world. And much of what little traffic there is goes right past South Africa and onto the far east - to Hong Kong and Singapore. These ships travel at up to 25 knots. So we've got to make contact with them, or their head offices, well before they appear anywhere on the visible horizon - or even on the VHFradio horizon (about 100 miles). To allow enough time to negotiate and agree passage with HQs.
The Tristan government has been using a professional ship tracking system that shows realtime position of ferries and all ships over 300 tonnes around the world. Particularly for ships in South American ports that might be coming this way. There is a similar but free system on http://www.marinetraffic.com/ais/ . Check it out to see what's happening at your nearest port. Another website http://www.sailwx.info/shiptrack/ uses satellites to track vessels further out in mid-ocean. But a lot of what I thought were ships near Tristan turn out to be floating weather bouys.
Amazingly, some shipping companies advertise berths on their cargo ships. I've been in touch with several asking if any of them are going near Tristan. Generally though that is going from port to port - and not making unscheduled stops. You can cruise the world on a cargo ship. (About $100 a day full board if you are interested.) One passes Tristan every 77 days - and it picked up another stranded visitor and took her to South Africa a few weeks ago.
Anyway we've just heard back from a shipping company which is due to send a 268 metre long container ship from Brazil to Port Elizabeth, South Africa in a few weeks time. They gave us a quote of £30,000 for passage to South Africa. A bit steep, I think. That apparently is the cost of a 500 mile diversion for a 268 metre long container ship.
I guess my best chance is the next scheduled sailing of the Edinburgh. At least I'm seventh on its passenger priority list of 12. So travelling is more likely. I'm slowly getting over my disapointment at not getting home as planned and gradually becoming resigned to another month on Tristan. Which is not so bad - it's a pretty amazing place after all!