Water Pumps for Cooling - To 'Push', or To 'Pull'

[Panther6834]

For those who've read about and/or seen the photos of the dual-rudder mod of my ProBoat Shockwave, you know that I did it to help it turn equally well in both directions. The reason behind the mod was because I intended to use the Shockwave as a "part-time rescue boat". The conversion also involved swapping the stock ESC for a SeaKing, and swapping out the 2000kv motor for a 1350kv Leopard.

However, it's still too fast, doesn't have quite enough torque...and, due to it going much shower, the water cooling is extremely inefficient. I've decided to take the conversion another step, slowing the boat even further, giving it more torque, and turning it into a "full-time rescue boat". My initial idea in this 2nd-stage conversion was to replace the brushless electronics with brushed (Traxxas...please, don't anyone think of 'killing' me...lol), and completely getting rid of the water cooling lines. Unfortunately, this plan want going as well as I had hoped...so, I've got another idea.

I'm going to keep the SeaKing ESC, as well as the dual water cooling lines (one pickup on each rudder, with each 'exit' on the opposite side)...and, as for the motor, I'm dropping it even further, to a 1050kv Leopard. To "fix" the water cooling line problem, I'll be installing a pair of 370-based water pumps...which leads me to my questions, starting with "push, or pull"? Is it better to 'push' the water through the system (as I'm describe in Option 1) to or to pull it through (described in Option 2)?

Option 1 - Push: Water in through rudder pickup, then through water pump, then through motor or ESC, and finally exciting the side.

Option 2 - Pull: Water in through rudder pickup, then through motor or ESC, then through water pump, and finally exciting the side.

So...which is better - push, or pull - or, does it even make a difference?

The second question has to do with location placement of the pumps. It's it better to have them closer to the rear of the boat, thus allowing less tubing to be used...but, at the same time, adding additional weight to the rear, throwing off the front/rear balance? Or, is it better to move them forget forward (closer to 'center'), keeping the front/rear balance somewhat equal...but, at the same time, increasing the length of the water cooling tubing?


~ More peace, love, and kindness would make the world a much better place

[RaceMechaniX]

Option 1, and mount the pump as close to the rudder pickup as possible.

[Raydee]

Do these pumps pass water through if they lose power??

[Panther6834]

Do these pumps pass water through if they lose power??

Obviously not. No power means no 'pump', which also means no 'flow'. With the 'pump' being operated by 370-can motors, and those motors receiving power via RJ connectors plugged into the receiver, if the receiver isn't receiving power, the pumps wouldn't receive power.

Of course...here's a 'curiosity' question for you - If the ESC & motor aren't receiving power, then why would the pumps need power?


~ More peace, love, and kindness would make the world a much better place

[RaceMechaniX]

I power almost all my FE boats with an external battery and switch like all gas and nitro boats. If the esc fails for whatever reason the pump will continue to cool the esc and motor. This becomes critical if the ESC is on fire.

[Panther6834]

I power almost all my FE boats with an external battery and switch like all gas and nitro boats. If the esc fails for whatever reason the pump will continue to cool the esc and motor. This becomes critical if the ESC is on fire.

If an ESC catches fire, I don't see how operating water pumps would be of ANY help. The water would only be going through the heatsink's cooling tube. As the fire would, obviously, NOT be in the cooling tube, the pump operating would be useless .

I know this has nothing to do with RC, or boats, but, imagine installing a building's fire sprinkler system only in the offices, but none in the hallways, or stairways. If a fire breaks out in the building, sure, those in the offices will (sorta-kinda) be 'protected'...but, as there are no sprinklers on the hallways or stairwells, not only will the building still burn down, but the people inside will probably parish. Now, I'm not trying to be morbid - the point is, just like the people wouldn't be 'protected', neither would the boat's ESC, or the boat.


~ More peace, love, and kindness would make the world a much better place

[plinse]

The criticality comes from possible leaks, the boat could sink itself by pumping water.
As long as the system does not leak it just doesn't matter, neither positive nor negative.

Pushing water the pumps can work much better then pulling and yes, impeller pumps allow water to pass also when switched of, while gear pumps would block water flow when not running.

[Panther6834]

The criticality comes from possible leaks, the boat could sink itself by pumping water. As long as the system does not leak it just doesn't matter, neither positive nor negative.

Pushing water the pumps can work much better then pulling and yes, impeller pumps allow water to pass also when switched of, while gear pumps would block water flow when not running.

Starting with your second point, that makes sense. With these being based on 370 motors, I'm 99.9% certain they're impeller pumps. The fact that, after turning the boat (and, this, the pumps) off, and disconnecting the water lines from the rudders, I was easily able to blow the remaining water out...but, only from the 'entry' ends (trying to blow the water out from the 'exit' ends proved all but impossible).

Getting back to your first point, that also makes sense...especially if the system has any "leak points"...which makes even more sense to NOT have the pumps operation (as suggested by 'RaceMechanix'). The whole "in case the ESC is on fire" thing made no sense, whatsoever. Thankfully, there doesn't appear to be any leaks. I've had the boat approx 15 months, and it's been in water quite a few times (remember, until now, it's been a "part-time" rescue boat, so it's also been used for "fun"), and hasn't leaked...and, hopefully, it never does.

As originally suggested, I installed the pumps as close to the transom as possible, cutting each line approx 1.5" from the tensions. For initial "testing", I used my usual "initial testing facility", also known as the bathtub, placing the boat in for several minutes with it turned 'off', followed by another 10+ minutes with the boat turned 'on'. Through all that, there were no leaks (0 water inside the hull), and the pumps operated perfectly (constant stream of water exiting both sides of the Shockwave). However, before I take it to the lake for "performance & rescue testing", I'll be installing the OSE 3/16" strut & cable.


~ More peace, love, and kindness would make the world a much better place

[nocebo]

It shouldnt actually matter if the pump is placed on the entry or exit, assuming there is not excessive drag in the system. The pump basically creates a pressure differential, and it doesnt matter where in the system the differential is, it will still create equal flow. I would aim to place the pump as low as possible in the boat, and probably close to the entry, so that it has an easier time priming. The one caveat is that if you have the pump on the entry, and you burst a water line somewhere, then the pump will basically fill the boat up with water, which would not be good.

[Jonathan DeMaria]

Why not get a low kv motor 600 kv or so