41amps is bloody hefty. Think about the weight of cabling. Probably more worthwhile having a waterproof case on the rover as the batteries may weigh less than the thick cables you'll have to run to cope with 41amps.

That is one hefty current draw.

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the 1000gal pump I looked at was only 3 amps going full power so not to bad at all

with 25m of 16guage cable you'll lose about
1.9v @ 3amps
3.9 @ 6amps
5.9 @ 9amps

which is pretty crippling... (ok at 3 amps, but not much more)

but... the volt drop will be half of that much if you run from 24v batteries....

(you can setup the speed controllers to limit the motors to 12v... so even if you lose 12v down the cable, you'll still have 12v at the motors)

then you could use speed controllers like these

http://www.ebay.co.uk/itm/New-10A-DC-12V-24V-36V-DC-Motor-Driver-Motor-Speed-PWM-Control-Controller-UK-/231042535942?pt=UK_BOI_Industrial_Automation_Control_ET&hash=item35cb355206

but wire them up to your joystick at the surface... get an analog joystick and you can use that for direction and speed control.... how many motors do you plan to use ? 2 for forwards/backward/turning and 1 or 2 for up/down?

if you've got 2 for forwards backwards, it might be easiest to just use 2 joysticks for those, one for each motor - something like these
http://www.ebay.co.uk/itm/Job-Lot-of-4-Trust-Predator-SV-85-Joysticks-BRAND-NEW-/221280700163?pt=UK_Computing_Remote_Controls_Pointers&hash=item33855b8703

of you can get stand alone joysticks/leavers and mount them to your own box

also... lights... guessing you'll need a decent bright LED light too ?

I get my driving licence back on the 14th of November (bloody speed cameras) - if you need a hand wiring it up after that give me a shout and I'll come down and give you a hand, would be a bit of an adventure :-)
(could also bring down a couple of old van batteries you could keep, bit old and no good for starting an engine any more, but more than enough for what you need :-)

you'll need some relays too, to turn the power to the motors on/off forwards reverse

something like these

http://www.ebay.co.uk/itm/CAR-BIKE-12V-40-AMP-5-PIN-CHANGEOVER-RELAY-SWICH-X-5-/400165316812?pt=UK_Cars_Parts_Vehicles_Terminals_Cabling_ET&hash=item5d2bb628cc

they have moving pasts inside, so when you cast them inside acrylic/whatever you'll need to have them standing up (connections pointing down) so the insides don't fill up too

you need 6, 2 for each motor

I can sort you out a wiring diagram later if you want?

it's pretty easy, they have 2 inputs and 1 output, then a positive and a negative to make them switch


you want to wire them up with positive to one input and negative to the other input, and one motor wire to the output

then wire them so without power they're all negative

when you supply power to one, it switches over to positive and makes the motor go one way

of you switch the other relay, so the other motor wire goes positive and the motor goes the other way :-)

but then he'll have to run 3 x thicker cables down, instead of just 1 and the extra network cable for control


cold do it that way tho... depends how much drag there will be from the current acting on the cable... I was assuming it was going to be going deeper

you'll need some relays too, to turn the power to the motors on/off forwards reverse

I was under the impression using on/off/on DPDT switches, that you just wire it so that the "on" on one side is wired opposite to the other "on" = reverse direction on the motor?

Keeping things simple, all I need is 3 of the above switches, connected to the power source and the motors. Job done. No need to mess around with relays and the likes. Seems to have worked for other people? o.0

Dremelled holes through each of the connectors and cable tied the tubing together. This way the tubing will flood/drain quickly, and hopefully the cable ties will be as strong as if the tubing was glued, plus it'll mean I can adjust things if necessary. The black square at the front is part of the GoPro packaging. Going to use that for mounting the camera.


Frame 2 by Chris_Moody, on Flickr

Pontoons are wider gauge tubing, the end caps are fixed in with milliput and araldite, and taped over to hide the sealing job. Painted it bright orange to help make it visible from above when in the water.


Frame 3 by Chris_Moody, on Flickr

Got a jump starter and the resin. Also found a local model shop and sorted some propellers out, but annoyingly I think that they're not totally suitable. They only have a screw thread at one end. Looking at the various adapters I could use to attach to the non-threaded motor shaft, they all require the prop to have a completely drilled out shaft/hole.

Will probably start to mess around with the cabling and electric later.