This was one of the highlights of my trip. The Yapei Queen is a ferry which runs the length of Lake Volta twice a week, from Akosombo in the South to Yeji in the North, and back again.
The ferry is a working ferry, carrying mostly yams (up to 40,000 at a time!!), but also cattle, trucks and people. Downstairs is third class, a large room of benches and tables, and only for the very brave or the local. Upstairs, though, are three first class cabins, which are delightfully comfortable and only cost about $20 for the trip - trust me you want to be in one of these; they are air-conditioned, clean and contain a basin with running water. The shower and toilet are shared with the crew, but are also in immaculate condition. There are only 6 berths though, so it would be wise to make a booking. You can phone the ferry company from the tourist office in Accra. I did this, and although no one on the boat could remember the booking, it did me give me some preference in securing a berth!
The trip south-north is the easier to get on. It leaves from Akosombo on a Monday afternoon, and arrives in Yeji 24 hours later. It does, however, leave you having to spend the night in Yeji, and from the brief glance I got of the hotels there, that wouldn't be much fun. I chose to catch the ferry north-south which, although requiring better timing to catch, and a round-about route throught Tamale, gives an extra night on the ferry, more daylight time on the boat, and a very pleasant 9am arrival in Akosombo.
To get there from the North I spent a night in Tamale, caught the 6am bus down to Makongo, and the ferry from Makongo to Yeji, arriving in the heat of the afternoon. Once there though I simply waited in a hotel and had a cold beer until the ferry arrived. Although we only left at 3am the next morning, I was allowed to spend the night on the ferry - which saves a very early morning wake-up call!
The trip consists mostly of leisurely travel down the lake, with lovely scenery on either side, punctuated by several stops to pick up crates of yams. These stops are generally very long - every yam is unloaded by hand from a truck at the stop, carried aboard in buckets and basins by women, and then re-packed in crates on the ferry (there is a forklift on the ferry, but at most of the stops there are no spare crates, so it can't be used). Packing seems to be the man's job. I don't know why. Packing several thousand yams by hand can take two to three hours, and while it is curiously hypnotic to watch, I would advise taking a book.
The crew on the boat are very friendly, and with a little luck you may be invited onto the bridge by the captain or the first mate.
The ferry arrives in Akosombo port (just outside Akosombo town) at 9 on the Wednesday morning. Minibuses are waiting, and there is one for just about any destination in eastern and central Ghana.