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@yahoogroups.com, wrote :

James,

From the Super Maramu 20 00 Owners Manual...it states 7,000 watts or 510 amps

Best,

CW Bill Rouse
Admiral, Texas Navy
Commander Emeritus
Amel School  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] <amelyachtowners@yahoogroups.com> 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 not leak a t 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