boat speed controller

don_jarr · 19-08-2007

Hi all

As mentioned in another thread, the last time I had a boat on the water, the speed controller was a coiled tube and pivoting arm, operated via the servo. Now it seems everything is electronic and there are dozens of different ones.

So far I have found proper water proof boat ones, which’s seems appropriate, but as for the rest they quote all different amps, number of cells I’m getting a tad confused looking for a suitable unit.

So the motor is a Graupner Speed 900bb torque running off a 12v sealed lead acid battery. Quite a hefty motor, but then the boat is quite large, so I decided to go bigger prop run off a slower rev’ing more powerful motor. It’s not s speed boat, it’s a sort of cabin cruiser, so its more just to have fun with than zoom about.

Any suggestions would be hugely appreciated.

J Don

RickF · 19-08-2007

Don,

The first thing is to find the stall current of your motor. Basically this means running it at full voltage with an ammeter in circuit and then physically slowing and stopping the prop and noting the current. This represents the max load your speed controller (or ESC) will be required to take. Thats all you really need - operating voltage and max current.

Rick

**Bunkerbarge** · 20-08-2007

Completely agree with Rick. From the figure you get you want a speed controller with enough of a safety margin over your stall current to be reliable but not too much that it won't cut out in the event of an over current when you get stuck in the weeds.

I would suggest about 10-15% over the stall current then go to the next available readily made unit above. So if your stall current is 8 amps then allowing 10%, 8.8, will take you to a 10 amp speed controller.

don_jarr · 20-08-2007

Hi all

I took this off the graupner website as I don't have a meter thingy, and it seems to have all the specs on it:

SPEED Torque motors
Special high-performance motors with integral
suppressors. Characteristic high torque at low rotational speeds, therefore ideal for use in direct-drive model boat power systems with large
propellers.

Specification
Nominal voltage 12 V
Operating voltage range 6 ... 40 V
No-load rpm 6500 min–1
No-load current drain 1,1 A
Current drain at max. efficiency 8 A
Current drain when stalled 54 A
Max. efficiency without gearbox 71 %
Length of case, excl. shaft 85 mm
Diameter 51,5 mm
Free shaft length 15 mm
Shaft diameter 6 mm
Weight 645 g

Don

Mankster · 20-08-2007

Stall a Graupner 900 on weeds? Its got a bunch of torque. If the prop fouls solid and you applied power, the boat is likely to be spinning in the water

don_jarr · 20-08-2007

Hi all

The local pond is kept in good order and I have yet to see any weed there at all.

jankers · 21-08-2007

Go for a unit that does 15 or 20 amp, fit a 10amp in-line fuse.

Just make sure it will operate at the voltage you are going to use, and ensure it will operate in forward/reverse modes, some (aircraft/car) types only go forward.

J.

onassis · 3 Weeks Ago

Hi Don.
Eelctronics suppliers like maplins etc, can supply you with a standard 10 amp multimeter. if you bought a meter I would mail you the instructions on its use.
You can`t really guest-imate what size speed controller your boat needs by the blurb you have for the motor spex.

Aquarama · 3 Weeks Ago

Hi Don, have alook at the Elecronize web site, he does a fair ammeter for under £10.00 put it in line with batter/motor and run up in the domestic test tank, take the reading as the boat butts against the end and add 20%,regards Aquarama