To increase efficiency and speed, to diminish fossil fuel consumption to zero and to decrease motor maintenance cost African Cats has developed electric Motogens* that retract from the water if no charging or motoring takes place
- The resistance while sailing is les and the actual sailing speed increases because no sail drives, propellers, props shafts or shaft supports are in the flow of the water and the result is lower usage of motors.
- The motors are located closer to the centre of gravity making the yacht safer and more comfortable.
- Expesive folding or feathering props are no longer needed because they are lifted from the water when not in use.
- The grounding is very limited so prop anodes will wear very slowly if at all.
- The propellers do not corrode or attract growth decreasing its efficiency.
- The propellers in case of the use for catamarans is tractor mounted to increase the efficiency.
- The silent electric motors are located in the water under the bridge deck so noise in both the bedrooms and saloon is almost non existed and no heat is generated in the yacht.
- When under power from one motor or charging with one generator while sailing the other motogen* can be lifted to decrease resistance.
- When the props are fouled with Kelp ropes or fishing nets they can be cleaned very easy, just lift them from the water open the hatch on top and clean them.
- The brushless maintenance free electric motors are built to IP 68 so they are waterproof.
- We have eliminated thru hull penetrations under water so leakage is not possible.
- Large 4 bladed light weight slow rotating aluminium propellers have a higher efficiency than the normally used folding or feathering props and this is possible because of them being retractable.
- The efficiency is better because the props are not mounted close to the hull but and not in the turbulence of the keel so there is a better water flow.
- The weight can be lower compared to the normal electric drive or diesel propulsion depending on the use of type of batteries and generation or not.
- On top of the mast a 300 watt wind generator can be mounted to keep the batteries charged when moored, the advantage in mounting the unit on top is threefold: less noise; higher efficiency and a good sized wind vane.
- The propellers are counter rotating so there is no wheel effect and it increases efficiency because the rudders are now in line instead of counter steering the wheel effect.
- The propellers are mounted away from the rudders so the rudders are more effective while sailing and generating power (And no vibration).
- The spaces under the beds normally occupied by the engine/sail drive combination are now empty and can be used for other purposes and an extra buoyancy chamber is installed.
- When using the electric motors there is no exhaust smell, smoke, noise, soot and vibration and you do not have to fill your diesel tanks each time when you dock.
- If you are sailing too fast you can lower the props to increase resistance and slow down and in mean time recharge your batteries.
- When beaching the boat you can raise the legs and there is no chance of damage to motors or propellers.
- The electronic controllers are water cooled and are 95% efficient so not much heat is generated.
- A water heater in 24 volts dc can be included in the system to conserve more energy so it will not be necessary to first convert to 24 volt and then to 110 or 220 ac.
- It is possible to motor sail and by presetting the motors to an rpm setting, when the speed of the boat picks up because of waves or increased wind force, charging starts automatically.
- A range of 3 different electric motors from 10 up to 30 kW is available.
- With a RS 232 or USB connection it is possible to connect the system to your computer to monitor temperatures of the motor and controllers, motor rpm, torque and electrical consumption.
- The system has built in safety for overheating of the motor, if overheating occurs first the motor output is lowered, if the situation continues it switches down until cooled. The same is done with the controllers.
- Maximum and minimum rpm settings can be preset in order to use the least energy or to charge most efficiently. Charging normally starts at 300 motor rpm and the max prop rpm is set to a little over max hull speed, for instance if hull speed is 9 knots and it takes 1400 motor rpm to reach that speed max rpm setting is 1500. It is a waste to set it any higher since 1600 rpm will only give you 0.2 knots extra speed but the consumption of watts is 30 % higher.
- Maintenance, fuel and downtime is considerable less than normal diesel sail drive motors.
- Because the shaft is connected directly to the motor on one side and to the propeller on the other side and no thru hull bearings or P bracket are needed the resistance is far less and the efficiency much better.
- The motor housing is made from corrosion proof aluminium 5082.
- With the system 4 x 327 watt solar panels can be mounted on the bimini roof to charge the service batteries when not sailing.
- An automatic relay can be installed to activate the cross charger so when the service batteries are full excess energy is fed to thee propulsion batteries.
- In the GreenCat 445 we are using 2x 10 kW electric motors/generators
- The batteries used will be the new Europe batteries with 1 Kwh per 10 kilo weight we inted to install 28 KW or 280 kilo's and that enables us to run continuously for 4 hours at a speed of 7 knots. (This is not taking into account any recharging taking place from the wind generator or solar panels).
- Since the system is all electric it is ready for future Hydrogen generators when these become available and financially affordable.
- Optionally we can install an induction cooking to make the yacht complete fossil fuel free.
This system is also designed for mono hulls with single or twin installation where these motors will sit in a shaft close to the position of the standard diesel motor and can be lifted and lowered with hydraulic actuator. To decrease the resistance the openings are closed when the motors are in the up position.
It will be offered under the name 'GREEN-MOTION'
We have patented the system in 2011.
* Motogen = underwater motor / generator