A couple of years back, HFL partnered an American company in developing a diesel electric system.

The idea was simple: install the system in a sailing boat and use the propeller on the overrun on long passages to turn a generator to pump up the battery bank.

When the boat needed power, the batteries were fully charged and able to accommodate the demands made on them.

Now Fischer Panda has taken a slightly different route and launched its own diesel electric system that provides primary propulsion from the boat's generator.

At first, bow thrusters of 10 - 100kW were offered with claims of vastly increased performance with none of the conventional thruster drive's problems of hydraulic tanks and plumbing.

"What made this possible was the development of the company's permanent magnet (PM) electric motors, " said Barry Fower, managing director of Fischer Panda in the UK. "The motors are up to 70% smaller and lighter than a comparable conventional electric motor."

Those bow thrusters have now, themselves, been superseded by the company's Whisperprop system.

The system revolves around a central quiet encapsulated generator that can be located anywhere on the boat. The generator provides the power for the propulsion system as well as charging the on-board battery bank that enables unlimited use of AC power on board through inverter systems.

Fischer Panda says the generator can be sited virtually anywhere on the boat, giving designers much more flexibility when planning the layout.

A single generator can provide the power to run single or twin drive systems and bow or stern thrusters can be used.

"If required, " said Fower, "a system can use two smaller sets, something particularly suited to catamarans that can have a drive system in each hull."

Special unit

The generator is a special unit designed for the drive application. It's lighter and smaller than conventional units and two modes of operation ensure a very high efficiency of the system; one mode for propulsion ensures the generator is capable of producing ample power to drive the motor at full speed, while a second slower mode can be used during the nonpropulsion times. And this, says Fower, makes the whole system quieter and very much more fuel efficient.

The output from the generator is regulated to provide charging to the boat's battery system, this is very efficient charging at optimum rates. This enables inverter systems to be used to supply the onboard AC power. From a 12v battery bank it's possible to run five inverters in parallel giving an AC supply of 12.5kW pure sine wave.

The Fischer Panda permanent magnet electric motors are available with out-puts from 12kW to 150kW with a speed range of 0rpm to 4500rpm. The bearing can be integrated into the motor so no additional shaft bearing is required.

The electric motors give maximum thrust at low rpm, something not possible with conventional propulsion systems, and this also ensures maximum manoeuvrability at low speeds.

The PM motor is currently available in several formats :

DE - Shaft, with internal or external thrust bearing; DE - Saildrive; DE - Aziprop, 180infinity rotatable underwater drive; DE - Thrust, three sizes of bow/ stern thrusters.

When correctly installed the system is virtually vibration free.

It runs very quietly and is extremely compact and multiple control stations are available along with maximum efficiency.

Weight is considerably reduced and the distribution of the weight has much more flexibility.

The main advantages of the system are: it's extremely quiet;

it offers exceptional manoeuvrability; there's increased thrust (on bow/stern thrusters as well as main drive); it's practically vibration free; it provides all of the boat's power systems as well as propulsion;

any number of control stations can be used; it offers up to 50% fuel saving whilst operating in certain ranges; there are huge weight and space savings; it offers a very high level of system efficiency and it's the ultimate in environmentally friendly propulsion.

Fower told BB: "Electric drive systems are a well proven technology. For many years passenger ships and many other large boats have used these systems and Fischer Panda has now brought an affordable solution to the market making this very efficient system a real option on smaller commercial and pleasure boats."

The company has installed many systems and is pleased to report all are working well.

And there is a new Bavaria 49 with a WhisperProp system installed that's on a European tour that will end in the Med later this year.

"This yacht is available for inspection or trials if required, " said Fower.

Controllable pitch shows the way Darglow Marine Engineering in Wareham has been working on a controllable pitch propeller system that can be operated mechanically or electrically.

The benefits for sailing craft are enormous. The propeller can be feathered for sailing to present the minimum drag, while the blades can be adjusted under power to offer the best pitch for the boat, engine and conditions. Reverse is also much more positive than the folding prop with the stuck blade? Darglow's Richard Hares told BBhe's been working on the system for about 18 months using Norwegian West Mekan (WM) propellers and shafts.

The system is able to swing a prop up to 32" diameter and the pitch can be adjusted at all speed ranges, even during acceleration.

Used in power craft, the controllable pitch allows the helmsman to match pitch and speed precisely so the engine doesn't get overloaded at low speeds, with the consequent digging a hole in the ocean while labouring up onto the plane.

Adjusting from fine to coarse allows the engine to match revs and torque to get the best performance from engine and hull as the boat picks up speed.

Darglow says the efficiency of a folding prop is, in many cases, far below 50%. An optimally selected self-pitching prop can achieve around the 50%, while the best efficiency rating by far is achieved by a controllable pitch propeller that can reach up to 80% efficiency.

Contacts Fischer Panda UK Barry Fower T: 01202 820840 E: barry. fower@fischerpanda.co.uk Darglow Marine Engineering Richard Hares T: 01929 556512 E: mail@props4yachts.com