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[Inkaboat]

Good afternoon all, I haven't posted for quite some time, but I intend to fix that with this new build.
I have been building a Billings SMIT Nederland tugboat: working winch, scanner, lights and all, but now is the time to make something a bit more aesthetically pleasing!


I have a question on motors for the experts on here. There are two Mktronics G2 Hydra 30s sitting in the tugboat: vastly overpowering it, and I was wondering if they -or just one- would suit this boat. I build models, try them out, and they rarely move again so performance isn't a real issue, but at £80 a pop they are worth using elsewhere! They don't need water cooling. I know this because I used three of  them in a 48" MTB I built which fairly leapt out of the water without any running problems!
Here's the spec.


SpecificationsProduct Type – Speed Controller & MotorMotor Type – Brushless – SensorlessCurrent Limit – 30 AmpsDirection – Forwards/ReverseBattery Type – NiCAD/NiMH/Lead Acid/LiPoLipo safe – YesOperating Voltage – Maximum 12.0 VoltsSet up – Auto ‘Plug n Play’BEC – 1.5AMotor Short circuit protection – YesThermal overload protection – YesFailsafe – Built inDimensions – L42.0mm x W27.0mm x H16.0mmWeight – 95.0g inc motor
Motor SpecificationKV (rpm/v) – 1100Power – 120WMax Current (A) – 21Max Voltage – 15vDiameter – 28mmLength – 38mmShaftameter – 4.0mm
Your opinions are appreciated.
Thanks
John Barrett
Southampton.
Here's ghe ugboat!

[DJW]

Hi John


Another Riva Aquarama, excellent decision. 


I haven't actually used the G2 Hydra 30 units, but on the face of it / based on the specs they look well suited to the Amati kit, I do think you'll need both units. In the same boat I'm using 2 x 3530 brushless (same 1100kv as the G2s) on 3S LiPos, restricted by the transmitter to 80% output, and they're still a bit overpowered and draw 10A maximum. I think if you put PropShop 1415 propellers on those G2 motors they would work well. Given the G2 motors should rev at similar speed they may use a but more current to spin those props at full speed, but I'd have thought well within limits, and most time is spent at lower speeds anyway.  I see the motor sizes are smaller in diameter and longer in length (compared to usual outrunners) and this will help let you keep the motors low in the hull, so better prop shaft angle too.


If you went for LiPo power, I'm not 100% clear whether the Hydra 30 ESC units can handle 3S liPo's as they exceed 12V when fully charged (12.6V ish), I'd have thought they would be OK but maybe someone else can clarify..?  Running the boat on 2S would reduce performance quite a bit.  LiPos help keep weight down and power up but I know some folks don't like them.


My main feedback with this kit is that it builds heavy as it was designed as a static display model.  Building for RC needs weight saving to be taken into account at every opportunity, especially up at the bow.


Look forward to seeing the build take shape..!
Best regards
David.

[Inkaboat]

Hi David, and thanks for the welcome advice.
Looks like this tug will need some smaller motors!
John