It is slow and travels only a short distance, but builders of the Serpentine Solar Shuttle say it is the most advanced passenger ferry on UK waters.

The shuttle is powered entirely by the sun, cruises at 8km (five miles) per hour and carries 42 passengers.

Operators will offer one-way tickets for the 1km (two thirds of a mile) cruise, charging $2.75 for children and US$5.50 for adults.

The 14.5m (48ft) long shuttle has 27 solar panels on its roof and a maximum journey distance of 132km (82 miles)

Christoph Behling, who also designed the world's largest solar boat in Hamburg, Germany, said: "This is the most technologically advanced shuttle in the world right now.

"It is made of entirely stainless steel, which means it never gets old. It will pave the way for future boats and trains and other means of transportation."

The shuttle cost $421,000 to build, 20% more than a diesel boat of a comparable size.

Even on those dark, rainy days everyone associates with London, Behling said there will be enough sun to keep the ship running.

He is now working on a 300-passenger solar-powered ferry to run on the Thames, which he hopes could be ready in 2008.

A 60-passenger solar-powered train for London's Battersea Park is also a possibilty.