Green Motion retractable propulsion and generation

[fastcat435]

I would like to inform all multihull sailors that we at african cats have developed a new hybrid system with retractable electric motors that will be available from 5 up to 25 kw in steps of 5 kw up
The advatages are show below. please commend on ti or if you have questions let me know
To increase efficiency and speed and minimize fuel, maintenance cost and CO 2 emission African Cats has developed electric motor/generators that retract from the water if no charging or propulsion takes place.The numerous advantages are:1: The resistance while sailing is lowered 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.
2: The motors are located closer to the centre of gravity making the yacht safer and more comfortable.
3: Folding or feathering props are expensive and no longer needed because they are lifted from the water when not in use.
4: The grounding is very limited so prop anodes will wear very slowly if at all.
5: The propellers do not corrode or attract growth decreasing its efficiency.
6: The chance of lightning striking the yacht is less because the grounding of the yacht is minimized.(studies learned that yachts with sail drives have a higher chance of getting struck)
7: The silent electric motors are located in the water under the bridge deck so noise in both the bedrooms and saloon is minimal.
8: When under power from one motor or charging with one generator while sailing the other prop can be lifted to decrease resistance.
9: 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.
10: We use brushless maintenance free electric motors that are built to IP 68 so they are waterproof and are even preheated to prevent condensation.
11: We do not have thru hull fittings or shaft drives under water so leakage is not possible.
12: Large 3 bladed light weight slow rotating propellers have a higher efficiency than the normally used folding or feathering props and this is possible because of them being retractable.
13. While motoring with the generator running the fuel consumption is less then with the standard diesel propulsion.
13: the efficiency is better because the props are not mounted close to the hull but at 3 ft distance so there is a better water flow.
14: the weight is substantially lower compared to the normal electric drive or diesel propulsion.
15: The optional generator is installed under the guest king sized bed in a sound capsule and this area is also insulated to keep noise to the minimum. ( measured 47 DB at 2m)
16: 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.
17: the propellers are mounted away from the rudders so the rudders are more effective while sailing or generating power. ( and no vibration )
18: Spaces under the beds normally occupied by the engine/sail drive combination are now empty and can be used for other purposes or an extra buoyancy chamber can be installed.
19. When using the electric motors there is no exhaust smell, smoke, noise, vibration and you do not have to fill your diesel tanks each time when you dock.
20. If you are sailing too fast you can lower the props to increase resistance and slow down and in mean time recharge your batteries.
21. When beaching the boat you can raise the legs and there is no chance of damage to motors or propellers.
22. The controllers are seawater cooled to increase efficiency, keep the noise and heat to a minimum and the heated water is used to preheat the water in the water heater.
23. A water heater in 120 volts dc is included in the system to conserve more energy so it will not be necessary to first convert to 12 volt and then to 110 or 220 ac.
24. It is possible to motor sail and preset the motors to an rpm setting, when the speed of the boat picks up because of waves or increased wind force, charging starts automatically.
25. A range of 5 different electric motors from 4 up to 25 KW has been developed (compares with 13 up to 82 HP)
26. With a RS 232 or USB connection it is possible to connect the system to your radar, GPS or computer to monitor temperatures of the motor and controllers, motor rpm, torque, electrical consumption. So far with the Raymarine, Simrad and Navman system
27. The system has build in safety for overheating or stuck propellers, 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.
28. Maximum and minimum rpm settings can be preset in order to use the least energy or to charge most efficiently. Charging normally starts at 120 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 900 motor rpm to reach that speed max rpm setting is 950. It is a waste to set it any higher since 1100 rpm will only give you 0.2 knots extra speed but the consumption of watts is 30 % higher.
29. The cost of maintenance, fuel and downtime is considerable less compared with normal diesel-saildrive motors.
30. 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.
31. The motor housing is made from Marine grade aluminium 6053 and coated with Coppercoat/epoxy so corrosion is non existent and resistance is minimal.

This system will also be offered to other yacht builders both for catamarans and monohull installations because a retractable system for monohull yachts is also developed.
It will be offered under the name “GREEN MOTION HYBRID”

[fastcat435]

here are the first pictures of the testing unit in our basin in South Africa as it is lowered into the water , it takes 10 seconds from fulll up to full down or from full down to full up position.
The Green Motion is attached here to the rear inside stringer as iot will be on the real FastCat 455
Greetings

Gideon

[David M]

Great idea!

Given 25kW is 33.5 hp, do you plan on increasing the electric motors horsepower for your larger designs? What will be the largest genset in hp on the FastCats?

[fastcat435]

Originally Posted by David M

Great idea!

Given 25kW is 33.5 hp, do you plan on increasing the electric motors horsepower for your larger designs? What will be the largest genset in hp on the FastCats?

Hallo David The difference between electric motors and diesel or gasoline powered motors is that the power on a electric motor is measured on the shaft in other words , it is nett hp or Kw while in diesel motors it is crankshaft hp and all the parts like a alternator , water pump stern tubes P brackets and sail drives or transmission all cost energy that you have to take of the gross energy supplied by the diesel.
Another advatage is that the torque is there with o rpm
The comparising between a diesel and an electric motor is
10 Kw of electric power will give you the equivalent of 33 HP diesel power
This is both calculated and tested by us.
This is a rough calculation but if I tell you that 6 months ago a FastCat 435 loaded to 11 tons made the trip From Durban to Madera with 2 x 4.5 Kw (16 hp ) solomon tech motors installed inside and she was able to cruise under motor power at a speed of 6.5 knots while with 2 x 30 HP diesel we can reach 8 knots max .
The 25 Kw electric motor will be able to propel the 555 at a speed of 9 knots. The diesel equivalent for this electric motor is 82 hp and becasue of the high torque the 555 will accelerate faster and will stop faster .
Another advantage is that you can go from full power forward to full reverse immediately saving seconds over a diesel for instance iof an emergency stop has to be made because there is a log or treetrunk in front of you in the water.
Another advantage of Green Motion is that especcially with very little wind when resistance matters a lot you can still sail better because the motors are lifted from the water saving around 7 % in resistance.
Another fuel saving and less noise, smoke and vibration.
In the 555 I would advice 2 x 25 KW gensets but larger is possible , up to 40 is available and in the gensets designed for us are always both 144 volts and 24 volts available so both your service and your propulsion batteries will be charged
These generators are both autostart and autostop so when one of the levels of service or propulsion batteries drop below a preset voltage the generators kick in and also stop when another preset voltage is reached.
These generators do not start together , first number one comes in and when the generated power is not enough the second one comes on line
The starting sequence can be switched , otherwise it could happen that one gen set has 4500 hours on the clock while the other is just passed 1000 hours , the added advantage is that not only have you got redundancy with having 2 motors but also 2 generators.
We have chosen for dual generators instead of one single large unit because it saves a lot of fuel if the need is for only one generator.
A generator that is running half power still consumes almost as much fuel as when it is running on full power.
It is also better for spreading the weight in the boat

Greetings

Gideon

[colemj]

Originally Posted by fastcat435

The Green Motion is attached here to the rear inside stringer as iot will be on the real FastCat 455

Hi Gideon,

I guess I'm too dimensionally challenged to see this. I see the motor attached to what looks like a fiberglass beam attached to a metal scaffold. There is a piece of a boat hull in the picture, but I can't figure out why and it seems to be in the wrong orientation to actually be how the motor would work. Do you have a line drawing of the expected motor placement on the boat. I apologize if you have previously posted one.

Mark

[henryv]

Gideon
I am curious as to what you used to determine the 7 % resistance differential when comparing to traditional inboard drives. Was this based on fixed props or did you consider feathering or folding props?

[fastcat435]

Originally Posted by henryv

Gideon
I am curious as to what you used to determine the 7 % resistance differential when comparing to traditional inboard drives. Was this based on fixed props or did you consider feathering or folding props?

The 7 % resistance is based on Fixed props 18 x 18 since thois are used to generate energy wiht this system.
Normally if a cat has inboard electric propulsion and it want to generate with it you need fixed props and since we only do 900 RPM these props are bigger than normal.

Greetings
Gideon

[fastcat435]

Originally Posted by colemj

Hi Gideon,

I guess I'm too dimensionally challenged to see this. I see the motor attached to what looks like a fiberglass beam attached to a metal scaffold. There is a piece of a boat hull in the picture, but I can't figure out why and it seems to be in the wrong orientation to actually be how the motor would work. Do you have a line drawing of the expected motor placement on the boat. I apologize if you have previously posted one.

Mark

Hallo Mark

the part you see is only a part of the boat.
the prop is pointed to the rear
attached is a drawing
Greetings
Gideon

[Lodesman]

Gideon,

Any thought to using a tractor (propeller in front) arrangement? It's more efficient.

Kevin

[slomotion]

This is quite different from the previous design:

the New Fastcat 405 please comment and help us making the perfect 40/41 ft cat

Pros/cons?

[sluissa]

I really like this setup, and if I ever get the finances and the initiative, I might try to set up something similar on my 20 foot mono.

[shadow]

Looks and sounds GREAT!! Keep us posted as I would be VERY interested on getting this arrangement in the future.

[geekclothing]

Hi Gideon,
a number of designers ie schionnings have designed drop down outboard compartments/legs. Would the greenpower fit one of these and what is the cost??

[David M]

Gideon,
I ran the math and it is not making sense as far as your naval architects estimates of a diesels loss in horsepower between the crankshaft and the end of the propeller shaft.

You said that your 10kw electric motor is the equivalent of a 33 horsepower diesel after you subtract out frictional losses. A 33 horsepower diesel converted to kilowatts would be 33hp times 745 watts/1 horsepower which would be a 24,585 watts or a 24.5kw diesel...correct?

Lets use your numbers and say we have diesel that produces 24.5kw at its crankshaft and then produces 10kw at the propeller shaft. This means that 24.5 - 10.0 = 14.5kw. Therefore 14.5kw is lost as heat energy between the crankshaft and the end of the propeller. This would be a 60% loss from friction between those two points. I know there is some loss but a 60% loss? Do yacht diesels really have a 60% loss between the crankshaft and the end of the propeller shaft? I know for ships it is far far less. Is my math wrong?

This is what is typically lost in shipboard propulsion plants through frictional losses:
The Speed and Power of Ships: A ... - Google Book Search
Its generally well under 10%

David

[fastcat435]

Originally Posted by slomotion

This is quite different from the previous design:

the New Fastcat 405 please comment and help us making the perfect 40/41 ft cat

Pros/cons?

You are right but the other design is made for monohulls !!!
there are many ways to implement this system.
greetings