3.5 cat to electric tow boat conversion need motor opinion

[eric stockon]

ok as the title says im converting my 3.5 cat to a tow boat trying to do it with what i have in the bins i am going to get new motors tho and a pair of new 6 cell packs, im gonna use my old novak evx speed control and i got the gearbox at 3.86 to 1.

im thinking about a pair of 65 turn crawler motors

Performance Specs:

• (At no load) RPM @ 7.2V : 7000 (±10%), .65Amp Current
• (Max Efficiency) RPM @ 7.2V : 5900 (±10%), 2.79Amp Current

or a pair of 55 turn

Performance Specs:

• (At no load) RPM @ 7.2V : 8000 (?10%), .75Amp Current
• (Max Efficiency) RPM @ 7.2V : 6800 (?10%), 3.35Amp Current

and the have a 80 turn

Performance Specs:

• (At no load) RPM @ 7.2V : 5500 (?10%), .45Amp Current
• (Max Efficiency) RPM @ 7.2V : 4450 (?10%), 1.38Amp Current

and a 35 turn

Performance Specs:

• (At no load) RPM @ 7.2V : 12500 (?10%), 1.25Amp Current
• (Max Efficiency) RPM @ 7.2V : 10400 (?10%), 4.62Amp Current

the prop i have now is a octura x450 im looking for run time low amp draw and the power to pull a gas tunnel back if needed i know my rock crawlers would run forever it seemed like with this style motor.

made the radio tray and the rudder mounts and motor plate reinforcement on a cnc plasma figured the rudder needed to be in the center for this application got a few holes to still fill and im working on the new deck still

 

[eric stockon]

got the deck made and mounted, the boom is installed now to figure out what prop to use. did some testing with a single mabuchi 540 and one battery dont think im gonna need anything crazy when it comes to motors with the gear drive. the old battery got warm but motor and speed control did not warm up at all. the prop does not work it wants to cavitate and its way down in the water.

 

[eric stockon]

107 views and no advice i can't believe nobody can help out on this, o well ill get it lined out. looking at tug boat props

 

[Jim Caldwell]

At 4800 rpm with a plastic 447 fully submerged, I get about 10 mph and 5 lbs. of thrust.

Are you sure about the gear ratio given that small 24 tooth and 48 tooth is 2.00 to one?

That 540 is about 2000 rpm per volt, way too high.

 

[BrianTooms]

I'm on my fourth rescue boat I started with a Traxxas Villian Ex but have moved to tugs now as they are way more efficient. Definitely go to a tug prop it will make a huge difference in pulling power with no cavitation. Vac-U-Tug has some great inexpensive 1 3/4" plastic props or you can go to a Dumas prop. I'm using the 6v-12v 545 5 pole motors on a 3s lipo with direct drive. Cordless drill motors can be another option. A 12v SLA battery would let you run all day long. If you need pics or suppliers let me know.