The SM does not have any factory installed protection for the bow thruster circuit. On my boat the fuses on the battery terminals have a total rated load of 500 Amps, which is reasonable based on the ampacity of the wire used, and has never blown while in use.
And... since I am on the boat, rather than calculating, or looking up, or guessing... I figured a bit of measurement is in order. With fully charged batteries (and charger off) using the Magnetronic Amp meter to measure the current draw, and my Smartguage to simultaneously display voltage, here is what I find:
The bow thruster draws 420 Amps at 24.1 volts. That's where it stabilized after about 5 seconds. That's with the boat tied tightly in a slip, so any movement of the hull would (slightly) reduce the load on the prop.
It figures... almost exactly splitting the difference between what Amel has in the manual, and what the motor nameplate says. If it matters, this motor was just professionally overhauled last year with new brushes, windings, etc.
Back Creek Annapolis, MD
---In amelyachtowners@..., <lokiyawl2@...> wrote :
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.
SV Sueno, Maramu #220