Solomon Technologies

Advantages

Better Fuel Economy and Extended Cruising Range
These are two sides of the same coin. A major source of fuel savings and therefore, extended cruising range is our system’s ability to operate on electricity from the battery bank. When in port, the battery bank can be recharged at the dock using shore power charging. Under sail, the battery bank is recharged as water rushes over the prop, spinning the blades and shaft, turning the electric motor into a generator that charges the battery bank– a process we call regeneration. (For more information on advantages and techniques for successful regeneration, see regenerative motor sailing.) The result of the STI regeneration/battery bank electric fueling system is phenomenal efficiency, fuel economy and vastly increased cruising range. For the pure electric power sailor, bound for distant ports, raising the sails to take advantage of nature’s energy- wind and sun, the cruising range can be unlimited.

And for those with extended cruising plans and optional power needs, auxiliary power generation can be accomplished through the addition of a diesel generator or solar array backup power system. Even when motoring in hybrid-electric/diesel mode, that is, with a generator running, far less fuel is burned than with a conventional fossil fuel engine. The reasons for greater fuel efficiency are simple. While motoring with the STI system, boat speed is altered by varying the STI motor’s rpm electronically, with no wasted energy. By contrast, the fuel-hungry operation of a combustion engine loses efficiency and wastes fuel at every level of operation from idling to accelerating. As the fossil fuel engine builds rpms in order to reach productive speeds, parasitic losses can reduce efficiency by as much as 50%. The auxiliary diesel generator used by our system to recharge the battery bank is blueprinted to run at optimum performance, operating in a narrow rpm range where fuel efficiency is maximized.

Fuel economy also is improved through aggressive prop sizing. The STI high torque, low rpm electric motor with its large, high-pitch prop transfers force more efficiently to the water. (It is analogous to pedaling a bike in high gear instead of low; each pedal revolution takes you farther.)

The conventional fossil-fuel engine must turn at a relatively high rpm to produce the torque necessary to turn its prop, hence the need for reduction gears to keep rpm in the range required by the prop.

Those who find our claims of fuel savings hard to believe, need only understand the fuel-efficient characteristics of STI electric motor systems. The ST 36 and ST 74 motors are 92% efficient. They have only one (1) moving part and therefore suffer none of the multitude of parasitic losses of fossil fuel engines, including waste due to transmissions, fuel pumps, gears, and literally hundred of parts that create heat, vibration and the resulting major energy losses. And Electric Wheel owners have further fuel-saving weapons in their arsenal. The Electric Wheel with its planetary, ring and sun gears ratios is 96% efficient and power consumption can be reduced even further at low speeds by switching to single rotor drive.

We’ve developed fuel efficiency statistics from extended motoring on the Conser 47E that illustrate the savings possible with the STI electric drive system.

Even bigger fuel savings are realized in boats that are heavily equipped with on-board appliances. The generator efficiently produces electric power for all auxiliary systems as well as for propulsion. There is no need for a separate generator to run the air conditioner, and you never have to run a diesel propulsion engine as a generator to recharge batteries and sustain onboard electrical systems. Additionally, stored battery bank power allows you to use electricity on demand, and the generator only runs to recharge the battery bank, rather than running continuously while high voltage appliances are in use. Customers consistently motor about for hours of fun on the water without ever running their backup generators and have reported running their air conditioners overnight without having to turn on the generator.

A Seafaring Tale of Fuel Economy and Cruising Range
In 2001, the owners of an STI electric powered Cherubini 44’ crossed the Atlantic from England to the Virgin Islands in their elegant vessel, which features air conditioning and an all-electric galley with convection oven, microwave, breadmaker, refrigerator and deep freeze. They were forced to motor for two weeks straight through the windless Sargasso Sea and kept the air conditioning running the entire time to stay comfortable. Despite this prolonged use of the motor, appliances and the generator, they still had 1/4 tank of diesel fuel remaining from the 120 gallons they had when they left England.

The Cherubini’s fuel savings, cruising range, comfort and efficiencies are nothing short of miraculous to those who are just beginning to learn about the rewards of STI electric power drive systems performance. But to those of us who own and use STI electric power drive systems systems, it is “just another day in paradise.”