Solar Sailing Yacht From Down Under

SYDNEY, Australia -- August 23, 2000. It can make a steady five knots on a sunny day on solar power alone. Raise its unique eight airplane-like wings in a 10-12 knot breeze and the Solar Sailor, a 20 meter-long catamaran will make 7.5 knots... and not produce a single atom of water or air pollution.

For the past seven weeks, this unique tour boat has been plying the waters of Sydney's world-famous harbor, ferrying tourists and government dignitaries on sightseeing cruises in quiet, clean comfort and safety. Built for just under $2 million Australian, the Solar Sailor is the world's first solar/wind/hybrid-electric powered cruise boat. It is the brainchild of Australian physician, Dr. Robert Dane, an avid sailor and now EV (electric vessel) pioneer.

A Marine Revolution in the Making

What the naval architect came up with is a 20 meter-long by 10 meter-wide catamaran constructed of carbon fiber and fiberglass. She weighs 24 tonnes and is rated for a crew of 10 though she needs only two to sail her since much of her operation is computer-controlled. She can carry up to 100 passengers. Surprisingly her electric drive is rated at a mere 21 hp yet she can make 5 knots steady on photovoltaic power only.

The Solar Sailor carries enough solar cells to not only run both the vessel's electric drive motors but also her auxiliary electric systems and recharge the 4,000 pounds of lead acid batteries stowed low in her twin pontoons. All together, the Sailor generates enough electrical energy to power six homes.

Solar Sailor is a hybrid-electric vessel because she also makes occasional use of a LPG-fueled generator for recharging the batteries during night-time cruises and for helping the vessel make additional speed. With generator assist, the Solar Sailor will make 10 knots making her faster than comparable dinner-cruise, tour boats that ply Sydney Harbor. She carries enough LPG gas for about 12 hours cruising if the generator runs constantly.

Clearly, the most outstanding feature about the Solar Sailor are her eight sail wings, each of which measures 4 meters in length and 2 meters in width. They are mounted on movable "knuckles" which allows them to raise and lower. Their positions are controlled by the boat's computer system. If the sun is on the port side (left) of the boat, the port wings remain in a horizontal position while the starboard set raise to the ideal angle for maximum solar gain. Once the wind reaches between 10-12 knots, the wings are raised to take added advantage of this pollution-free energy (itself a form of solar energy). Dane explained that his team is still fine tuning the computer system to find the best settings for maximizing both solar and wind power on the vessel.

"We need to know three variables. The direction the boat is heading. We need to know here the sun is and where the wind is, and the computer has to make a decision based on those three things. We are currently optimizing those variables," he said.

Not only do the wings raise and lower, but they also rotate slightly so they can make maximum use of the wind. If the vessel is moving directly into the wind, the wings are automatically "feathered" to reduce leeway on the vessel. If Solar Sailor is moving anywhere from 45 degrees to parallel with the wind, the wings can be raised and rotated to achieve maximum forward thrust. Dane states that sail wings are much more efficient than cloth sails that will deform as the speed of the vessel increases, causing turbulence and drag.

The only major drawback of the wing sail is that you can't stow it or reduce its surface area (called reefing) in the event of a storm like you can a conventional cloth sail. The only thing you can do is turn it into the eye of the wind. However, in the Solar Sailor's case, the knuckle joint allows them to not only be feather but also be lowered and stowed.

Here's another perspective...