water cooling efficiency

[Ramtornado]

hi i have the water cooling jacket over the motor and i was wondering if there is water flowing inside the tubing are submerged under water all time
and when the boat is moving then its scooping water

how can i know how match water is flowing inside ???
and there is any restriction to the length of the tubing ???

i thought maybe to place a camera directed to the exit tube to see it working

any info will help

PS
I am using 4mm ID to 2.44mm inside diameter of the motor jacket water entrance

[westbeach]

Your best bet is to run the boat, and watch the water exiting the outlet. It should shoot out like a water canon. If it is a weak stream then something needs to be looked at.
Your tubing should be long enough to reach your components but not too long that they a coiled inside the boat.

[Make-a-Wake]

Just make a pass near you and look at the exit tubes...........5-8 inch stream outta be good.

[detox]

Sharpen your rudder.

capt,

Dont fill the hole. better yet make sure the leading edge of the rudder blade meets the front tip of the hole.. You can do this by sharpening the starboard side of the blade (the right) until the water pickup hole meets the leading edge.

Or

You can use a burr and elongate the hole to the leading edge..

Did any of that make since to.. cuz it hardly did to me and I said it!

Grim

[Fluid]

...It should shoot out like a water canon. If it is a weak stream then something needs to be looked at....

This is another common misconception that leads to compromised results. The water has to stay in contact with the hot components for longer than a fraction of a second or the heat transfer will be poor. Water has a high specific heat, it takes time to absorb it. A short 2" to 3" exit stream is probably cooling a lot better than a 12-15" stream. Regardless of what you think you know, physics trumps "common sense".



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[westbeach]

But isn't it proportionate to the speed of the boat ( running either a rudder with h2O pickup or other pickups ). How would one restrict the outflow? so the heat dissipates into the water before exiting? Longer tubing from the pickup to the component? Please explain your solution. Thanks

This is another common misconception that leads to compromised results. The water has to stay in contact with the hot components for longer than a fraction of a second or the heat transfer will be poor. Water has a high specific heat, it takes time to absorb it. A short 2" to 3" exit stream is probably cooling a lot better than a 12-15" stream. Regardless of what you think you know, physics trumps "common sense".



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[CornelP]

Easy way is to insert a piece of brass tube in the outlet tubing. Any scrap piece with a thicker wall will do. I did this on my cat and it improved cooling significantly.

[rearwheelin]

Make sure that you minimize the amount of air that your cooling system is picking up, air is the biggest inaficiencie in your cooling system, if you are getting to much water and need to slow it down motorcycle jets work good or seal of the end of a water out less with some epoxy and redrill smaller hole, pressure test your system with 50 psi air too !

[ReddyWatts]

Does more water flow = better cooling?

Heat Transfer

The most efficient transfer happens at the GREATEST TEMPERATURE DIFFERENTIAL, therefore higher flow rates will always help with all other variables remaining the same.

* It is the Heat Transfer that we want to maintain as efficiently as possible, and that is best done with a higher flow rate. Rather than thinking that there won't be enough time for heat to move towards the cool water, and therefore compromising heat loss, it is better to think that there is more fresh cool water moving into the ESC and MOTOR and therefore, there is increased cooling.

The reason higher flow rates work better in an ESC and MOTOR is this:

There is more water with a larger temperature differential moving through the ESC and MOTOR- again removing more heat.

This is true even though a BOAT with a lower flow rate will have more time to heat the water in the ESC and MOTOR: since the heat exchange works best with the greatest temperature differential, longer “stay time” is counter-productive.

[Rumdog]

Makes sense. Never give it the chance to get hot.

[ReddyWatts]

We do not come close to moving the water so fast that it could empede heat transfer.

[rearwheelin]

I agree with the high flow rate as long as there is no air cavitating the water and compromizing heat transfer .

[ReddyWatts]

Yes, air will not transfer heat as good as water. The water pickup needs to be directly in the water and not coming from prop wash.

[Ramtornado]

well i am not shore that there is any flow in the tubing's

[ReddyWatts]

I usually install the water exit on the left side of the hull so it can be seen as it passes by. You can also have someone video it for a closer look.