The boat has a water cooled ESC and engine mount. These are fed from a scoop behind the prop. The water circulates through the ESC and engine mount and then out through the exhaust ports on the transom. The first attempt at plumbing in the monitors
was to simply tap into this cooling circuit, add a filter
and pump and feed the pumped water to the monitors
. This didn't work too well.
With the pump running the monitors
worked well, but water was sucked backwards out of the cooling circuit, drawing air in through the exhaust ports until the pump was sucking on air and the monitors
stopped working. I had sort of expected this might occur so I had a non return valve available ready to fit in circuit just before the exhaust ports to prevent this reverse flow. I had hoped I would not need to fit it as I am concerned that the extra flow resistance it will cause will reduce the effectiveness of the cooling circuit. The second, unexpected problem with this simple approach was that, with the pump off, there was enough water pressure in the cooling circuit that the monitors
continued to dribble water onto the cabin roof from where it drained into the hull. Adding the non return valve in the cooling circuit would only serve to make this problem worse owing to the increased pressure in the circuit. The last thing I want is for the boat to slowly fill with water, drenching all the electrics and gradually sinking so this dribble needs to be stopped.
After some thought, I decided that a diverter valve could be the solution. This would route the water either to the pump and monitors
, or to the cooling circuit. I reasoned that I would not want the monitors
working while the drive motor was running at high speed and so can afford to switch off the cooling circuit while the monitors
are operating. I had an interesting few hours making a servo driven cam mechanism which at one end of it's travel would squash the silicone tube to the cooling circuit while allowing flow to the pump and monitors
. At the other end it would cut off the water to the pump, and enable the cooling circuit. The servo would be driven by the same channel as the RCswitch that turns the pump on/off. Great idea, but it didn't work 🤔 The servo doesn't have enough power to turn the cam and squash the tubes and simply stalls. I need to try thinner tubes, or a more powerful servo, or something? Any helpful suggestions welcome...
Throughout the summer I have tried to keep the boat sailable for the local club sessions on a Wednesday afternoon. Not wanting to have to keep it in dry dock for an extended period while solving this issue I tried a different approach. I had available two solenoid valves so these were pressed into service as shown in the sketch. An RCswitch was constructed so that, with the pump on, valve A is closed and valve B is open. This routes the water flow to the pump and monitors
. With the pump off, valve A is open and valve B is closed, routing the water to the cooling circuit. This works!
In the video (my first ever on YouTube) you can see how water flows from the exhaust ports when the monitors
are off. I don't have a test tank at home so water is fed into the water scoop connection using a small aquarium pump. Now I just need jbkiwi to solve the smoker challenge so that I can add some smoke 😁