Unless your only mode of transportation is a bicycle, you've certainly noticed the hard pinch at the pump. Topping off a boat that carries hundreds of gallons of fuel – gas or diesel – is a particular whammy.

So when Island Pilot began to showcase breakthrough propulsion technology in the form of its DSe Hybrid – a 40–foot catamaran powered both by solar panels and diesel–electric motors – it attracted attention.

ISLAND PILOTPort bow view of Island Pilot DSe Hybrid model. Boaters have long used solar power to juice up batteries, but driving the boat is something else altogether. Indeed, to say the DSe is a radical design is an understatement. Reviewing the boat's specs and drawings and interviewing members of the team that created her, one finds innovation almost everywhere.

It shows in the hull. The boat is a catamaran cruiser – by itself, a relative rarity. But it also has unique full–displacement, wave–piercing hull designs that include a torpedo–like after–body.

It shows in the power plant. The DSe is powered at low speeds solely by the sun. When the batteries are not enough, it uses highly–efficient diesel–electric drives from Glacier Bay to supplement its solar wattage, both for propulsion and house electrical loads.

It even shows on deck. The massive solar panels also serve as an overhanging roof, simultaneously maximizing surface and shading the pilot house, helm and cockpit.

Perhaps most important, this is no demonstration project. The first two boats are already sold. Testing on Hull No. 1 continues in China and the first boat is scheduled to appear in the United States in May. Overall, the company expects to produce nine this year, with the base price for the first models estimated at $500,000.

Ruben Trane, the company's president, said the boat is designed for a live–aboard couple who are looking for moderate–speed, high–efficiency cruising. Though traditionalists may balk at a boat packed with leading–edge technology, Trane is adamant that nothing on the DSe can be considered "bleeding–edge."

"We're not in the business of adopting unproven technology," he said.

HIGH–VOLTAGE POWERISLAND PILOTView of Island Pilot DSe from port quarter.

The striking thing about the DSe is that it is essentially a high–voltage, DC–powered vessel. Even when the engines are burning fuel, it is in the service of producing electricity to drive the props.

The diesel–electric system utilizes OSSA Powerlite technology from Glacier Bay, which includes turbocharged, three–cylinder diesels from Mercedes that were originally developed for the Smart Car. They provide 25 kilowatts of DC power from their attached generators.

These may be the smallest electronically controlled, common–rail diesels in the world, but they have a power density that is roughly twice that of any other 25 kilowatt generator available. The engines are installed forward in the hulls, connected by DC power cables to the 35 HP direct–drive electric motors that turn the props. The generators are rated for propulsion duty and can deliver their full power rating for hours. They are also quiet. Glacier Bay specifications state that the 25 kilowatt generator, in its sound shield, generates only 65 decibels at a distance of one meter. That means that under normal circumstances, you will not hear it running.

Everything that happens aboard the DSe runs through the high–voltage DC (HVDC) power buss, which is the heart of the electrical system. Even half of the AC shorepower coming aboard is immediately sent to the battery charger and that buss (the other half powers normal AC loads, such as outlets and the entertainment system).

The solar panels are generating power through the buss and charging the batteries, which are Group 31 Odyssey units from EnerSys. The Glacier Bay diesel generators provide 240 volts of DC power to the buss, and drive the 35 HP electric motors.

In operation, the helm–mounted, touch–screen smart controllers provided by Glacier Bay will run in several pre–programmed modes. For example, there will be a "minimum generator" mode for short, slow cruises around the harbor, or at anchor in the evening when one would be willing to run down the battery banks a bit before engaging the generator to recharge them.

There will be another mode for times when the captain intends to run at high speed right from the outset. In this mode, the generators will come online immediately, supplementing any power being provided by the solar arrays.

Though we have not had the opportunity to inspect the boat, Island Pilot's description is that of an extremely power–efficient vessel.

ISLAND PILOTA flow chart showing the complex electrical system that powers the DSe Hybrid, including generators, solar arrays, shore power and batteries. A 13–KNOT CAT

On a sunny day, with the arrays producing peak power of approximately 6.6 kilowatts, the DSe will be able to go at least 6 knots without any assistance from the generators. If you stay below 6 knots in the sun, you will burn no fuel at all. And if you anchor in the sun, the solar arrays will keep the batteries charged. If you need lots of electricity – perhaps cooking meals with the air conditioning running and folks watching TV – one or both generators might run to provide the additional power required.

With the generators on and each producing its full 25 kilowatts, the boat should run as fast as 12 to 13 knots. And even at that speed, it will be burning only a couple of gallons of fuel per hour.

Preliminary testing on the first hull confirms that the boat will achieve 6 knots on solar power. At what the company calls her "sweet spot," at 7 1/4 knots, the DSe will reach 9 nautical miles per gallon without any solar assistance; 12 miles per gallon with 3 kilowatts of solar power; and 17 miles per gallon with a full 6 kilowatts of solar power. This converts to a range of 1,000 nautical miles at 7 knots without solar power, and up to 2,200 miles at 6 knots with a 3-kilowatt solar boost.

Trane says Island Pilot chose the best mature technology available. The solar cells, which are among the most efficient out there, are already available and installed in many homes and businesses. Under ideal conditions, they convert nearly 21 percent of sunlight to electricity.

And while Island Pilot hasn't completely settled all the warranty elements for the new boat, Trane notes that solar cells used in home installations are warranted for 25 years.

Island Pilot took the same approach with the batteries. The battery bank aboard the DSe will be capable of providing nearly 20 kilowatts of power, but does so using extremely reliable AGM batteries already in production and service. Trane said that if new battery technologies, such as lithium–ion, continue to develop in performance and fall in cost, they can be adapted in the future. The Odyssey battery banks have been subjected to harsh bench–testing at Island Pilot, with endless cycles of charging, discharging, overcharging, and discharging – and they have fared well. "We just can't kill them," Trane said.

One technical challenge the DSe team had to overcome was finding a regulator that could handle the specific voltage coming from the solar arrays, because the voltage was not typical for household installations. Island Pilot worked with Outback, which provided the special solar regulator on the DSe.

COMFORTABLE DESIGN

Based on plans and mockups, the boat appears to be an unconventional, but ultimately comfortable, design. Island Pilot separated the long main deck compartment into a master stateroom forward, with windows on three sides, and a salon and galley aft.

In the master stateroom, there is a walk–around queen bed, and steps down into the starboard hull, the length of which is devoted to the master head, dressing area and closets.

At the aft end of the main deck is a staircase to the bridge deck, with its two helm chairs forward and U–shaped seating at the rear. Side and rear window panels are roll–ups, while solid glass forward makes for an all–weather helm. Also at the aft end of the salon is a staircase to the port hull, where there is an entrance to the guest stateroom. It is built under the bridge deck, with two twin beds that can convert to a queen. The port hull itself contains the guest head and dressing and closet areas.

Several of the key appliances, including the water heater and cooktop, utilize the high–voltage buss for power. Others, such as the washer and dryer, take AC voltage from the inverter. There is also a low–voltage DC system for the helm electronics and some of the lighting – all of which is LED.

There is room on the foredeck for several lounge chairs and a drink table, and the deck has access to the anchor locker. Also forward are access panels to the two Glacier Bay generators.

Another feature of the DSe is that many items often specified as options will be standard. The boat comes equipped with two–zone air conditioning; a gyro–stabilized satellite TV system and a Bose home theater. The DSe will also be delivered with its own hard–bottom dinghy, outboard motor and davit, which is located aft between the cat hulls.

The boat will be equipped with a complete Raymarine electronics suite, including an autopilot.

"I'd really love to just get rid of the steering wheel completely and use the follow–up feature of the autopilot," Trane said.

He's not sure he'll be able to do that. But it shows the kind of thinking that is going on at Island Pilot.

ISLAND PILOT MANEUVERABILITY

While it remains to be seen whether independent testing verifies the company's performance estimates, the boat should be highly maneuverable, with wide–set engines on catamaran hulls and a bow thruster as standard equipment.

Its 17–foot beam is also modest for a catamaran, and it has a shallow, 29–inch draft that should expand the owner's ability to explore.

Hull No. 1 has been undergoing testing at the Her Shine shipyard in southern China. Island Pilot is testing the boat at two weight configurations and using four sets of propellers. Trane expects to have the first hull, which is already sold, to be moved to the United States in May. There is a deposit down on hull No. 2 and hull 3 is tabbed as the company demonstrator. Trane said he expects to deliver through hull No. 9 this year.

Island Pilot also has two more hybrids on the drawing boards. One is a boat called the SPRQ (as in "Solar Power – Real Quiet"), a downsized version of the DSe with a single engine and roughly half the solar–generating capacity. The house on this boat is similar to the Island Pilot 435 twin–stateroom boat, but the hull is a unique fine–entry monohull with amas (narrow outrigger–like hulls) outboard to port and starboard.

The other boat under consideration is an 60–foot version of the DSe. It will feature a four–stateroom and four–head layout, with the option of converting the two forward staterooms into one huge master suite. It will be equipped with two 75 HP electric motors from Glacier Bay, paired with two of its new 50–kilowatt variable–speed generators. There will be 14 kilowatts of solar power available from the rooftop arrays. This boat could be available as soon as 2010.

Tom Tripp is a freelance writer who specializes in technology and marine science. In addition to contributing features on new boats and technology, Tom writes a blog — Ocean Lines — here on Mad Mariner.