Thoosa 17000

[kroskris]

Hello all,

I am considering to use the DC propulsion system from Asmo Marine, the Thoosa 17000.

http://www.asmomarine.com/2005/asmo_uk/01.shtml

I already tried to reach somebody at the company, but there was no response, so i am asking here, if somebody would like to discuss the usage for such a system, or to propose a better solution.

The current status of the project is as follows:
-12m pleasure boat
-2xThoosa 17kW (96V) DC E-motors for propulsion
-16x AGM 12V 200Ah Gel batteries for energy storage

According to my rough calculation, the boat should be able to gain top speed of 16kts with this configuration.

I would like to know, if these motors withstand the longtime use, when planing at full speed for a longer period of time, without overheating or damage? Are these motors reliable enough to convince a future buyer of such a boat?
Are there maybe other, better electric propulsion solutions (motor with gearing and shaft coupling)...
Any usable comment is welcome.

Thank you and with best regards

[marshmat]

It's pretty hard to judge the system from the marketing materials alone. There is just too much missing data in the marketing copy at the link you posted to tell how the motor will perform in the real world.

The 17 kW "Thoosa 17000" appears to be roughly equivalent to a 23 hp diesel in full throttle operation; its continuous duty rating is 13 kW (17 hp). The claim of "replaces a 40-60 hp engine" appears to be based on a momentary 36 kW surge rating at 400 amps (double the nominal current at which the thing's controller hits its upper limit) and I would put no faith in that number. I couldn't find any performance curves with which to make a more detailed assessment.

The motors themselves appear to use permanent field magnets with a brush-commutated rotor and PWM controller. All of this is fairly simple, well known technology with no major quirks. I can't comment on the execution of this particular design without seeing one, or at least the drawings and performance curves for it.

Sixteen 200 Ah 12V gel batteries is a lot of weight (about 2200 lb). Such a pack, at 96 volts, would- at 50% cycle depth- give your twin Thoosa 17 motors only about half an hour of full-throttle running (400 Ah @ 96 V from two strings of eight batteries, each motor drawing 200 A at full power).

It'd be interesting to know how much you expect this boat to weigh, and what its drag curve might look like. Getting a 12-metre boat to plane at 16 knots with one tonne of batteries and only 46 hp is going to require some very light-weight construction, careful engineering, and a captain who is vigilant about over-loading.

[kroskris]

Thank you for your reply.

I also dont realy believed in this peak numbers to be real in everyday use, thats why i opened this thread.
To get up to 16kts with such propulsion system is also very optimistic, but a big chalenge, which i am trying to accomplish.

So, are there any better electric solutions out there, maybe more efficient?

PS
The boat will weight approx. 7 tons

[marshmat]

A motor rated at 94% efficiency (as this one claims to be, albeit at an unknown load and speed) is about as good as you are going to get without spending disgusting amounts of money. Even the CSERO solar car disc motor, arguably one of the best motors ever built, tops out at around 97-98%. If you're interested in this system, you really need to talk to one of the company's engineers (not their marketing people) with your requirements.

Seven tons of boat and a pair of Thoosa 17000 motors gives about 340 lb/hp. That might get a very slippery 12 m semidisplacement hull to 10-11 knots. But to plane it at 16 knots will require, I'd guess, at least three to four times that power.

[kroskris]

So, the Thoosa 17000 propulsion system might be the correct choice in this time and for reasonable money.

Offcourse i am optimistic about the top speed, nevertheles, it is a factor that attracts and sells, so if the top speed can be reached for just a small amount of time, then this will be good enough for the start.
The main attraction of my project is the electric propulsion itself and that is everyday usable and easy to operate and to maintain.

Thanks for the answers