#### Re: [Amel Yacht Owners] Re: Distributed vs. Conventional Electrical Systems

James Alton

Bill Kinney,

Good point about the voltage drop. I measured mine as dropping from 13.5 (charger was on so this was not an accurate test) to about 11.75 after a 5 second burst.

Does the SM have a breaker for the bow thruster and if so can you tell me the amperage?   I guess that the 6.3KW rating doesn’t tell us much since we don’t know how loaded the motor is.

Also, can someone tell me about how much free play is normal for a bow thruster?  I can rock the prop on my thruster back and forth about 3/16” without any resistance as measured from the tips of the blades.  The output shaft does not seem to have any play in it’s bearing so I assume that what I am feeling is the gear lash plus any play in the shaft to motor splines.

James Alton
SV Sueno,  Maramu #220

On Oct 18, 2017, at 4:16 PM, greatketch@... [amelyachtowners] <amelyachtowners@...> wrote:

What calculation did you do to convert 7000 Watts to 510 Amps?

P= V * A
510 Amps at 24 Volts = 12,000 Watts??

For what it is worth, the name plate on the motor on my older Super Maramu (they might not all be the same) is 6.3kW

To get a good number, for current draw you can't assume 24 Volts.  When you are drawing that much power, the voltage will drop, a lot.

For really high power draws like this, it is not unreasonable to assume as low as 18 Volts.

6,300 Watts/18 Volts = 350 Amps

If we do go with a 7000 watt rating, that's still "only" 388 amps.  A perfectly reasonable number to protect with a 500 Amp fuse.

Bill Kinney
SM160, Harmonie
Back Creek, Annapolis, MD

---In amelyachtowners@..., wrote :

James,

From the Super Maramu 2000 Owners Manual...it states 7,000 watts or 510 amps

Best,

CW Bill Rouse
Commander Emeritus
http://www.amelschool. com
720 Winnie St
Galveston Island, TX 77550
+1(832) 380-4970

On Wed, Oct 18, 2017 at 11:53 AM, James Alton lokiyawl2@... [amelyachtowners]  wrote:

Bill,

Is it correct that the bow thruster on the Super Maramu is 500 Amps?  And that is at 24 volts?  The thruster on my Maramu has a 100 amp breaker installed by Amel ( it has never tripped so I assume the normal draw is something below 100 amps)  and the voltage is only 12 volts so if my math is right it is about 1.5 hp which is good up to about 15 knots or so.   500 Amps at 24 volts would be about 16 hp?  Can you tell me the size of the original Amel breaker that is installed on the Super Maramu?

Thanks for all of your past help with my Amel.  And to update you on the bow thruster leakage.  After replacing the seals as instructed, the thruster did no t leak at all this season.    The thruster has also been 100% reliable thus far and is a tremendous asset IMO.

I will con sider adding some inline fuses to my boat as well just in case of a major short.

Best,

James Alton
SV Sueno,  Maramu #220

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