Best water pick-up ever!

[properchopper]

I bought one of these from ose for my sv-27/stiletto outboard conversion and I have to say this is the highest flowing water pick-up I've ever used! It almost looks comical how much water shoots out the side of the hull even at low speeds. I know its not the most hydro-dynamic piece, but there is no doubt that my esc is getting all the cool water it can handle. I will definitely be using more of these!!

http://www.offshoreelectrics.com/pro...?prod=oct-ocsw

I've been following this thread and think there's some good info on both sides of the controversy, but agree with those that state that a proper setup is most important and proactive in controlling temps - more important than depending on cooling to prevent problems on borderline setups.

FWIW I've used the pickup for an outlet ; picture on my beater T29. Makes the flow more visible.

[Old Sloppy]

I prefer a pair of these.
http://www.offshoreelectrics.com/pro...prod=ose-80400
one for an inlet and one for the outlet.

Harry

[PDR447]

the french fry analogy is the best analogy ever!

if you stick a french fry out a window while driving, eventually it will cool down. the faster you drive the quicker it cools down. so you either need more time out the window or more speed to get a cold fry. are we all in agreement here?

in an open loop system(FE boats) the boat motor is the french fry and the water is the air. the faster you drive(higher flow rate) the quicker the french fry will cool off.

in a closed loop system(cars) the the coolant is the french fry and the radiator is "out the window". the time the coolant spends in the radiator is the equivalent to the time the fry spends out the window. THIS is where the too high flow rate idea comes from. if the coolant isn't in the radiator long enough it won't cool down. just like if you don't fold the french fry out the window long enough it won't cool down.

now, with the closed loop systems we have two "fry out window" scenarios within the one system. the one above, and the radiator/air relationship. radiator vs air is an open loop system much like the boats and the fry/window. the radiator is the fry and the air is, the air. the more air you get over the radiator the quicker it cools down. that's why your fan kicks on when you're idling too long, you need airflow!

anyone care to disprove this? I'm open to learning...


EDIT: you may substitute the phrase "more heat removed" for "quicker it cools down" anywhere above. and more heat removed is the goal of every cooling system.

[properchopper]

Well it's raining & I'm bored so I thought I'd jump in to this discussion again with my latest thoughts. I have some boats with high flow rates & some with slow rates & I'd really like to learn more about what's most effective. I'm not sold on the french fry experiment application logic to water-cooled boat electronics ( and what a waste of a good french fry) ! What, at least in my thinking, is most important is the transfer rate between the heat source and the cooling medium which is critically tied to the contact time between these two.

Here's my lab experiments ( perform these at your own risk) :

Test 1:
Run your finger over a hot motor [ say 165 degrees] in one second total. How hot is your finger ?

Then do the same thing but take five seconds to do the same. Hotter finger, right ?

My take is that the longer the cooling medium (your finger) is in contact with the object to be cooled, the more heat transfer from the object to be cooled.

Test 2 : Build a ten foot by five foot bed of hot coals.
Walk (very !) quickly over them. I'm sure you've seen this done on some TV show or something. Feet maybe warm.
Now take ten seconds to do the same. Feet VERY HOT !

Again, the point I'm proposing is that the longer the cooling medium is in contact with the object to be cooled, the more heat extraction takes place.

Slower flow = better cooling
QED

Now go eat some french fries

[H&MWill]

Well it's raining & I'm bored so I thought I'd jump in to this discussion again with my latest thoughts. I have some boats with high flow rates & some with slow rates & I'd really like to learn more about what's most effective. I'm not sold on the french fry experiment application logic to water-cooled boat electronics ( and what a waste of a good french fry) ! What, at least in my thinking, is most important is the transfer rate between the heat source and the cooling medium which is critically tied to the contact time between these two.

Here's my lab experiments ( perform these at your own risk) :

Test 1:
Run your finger over a hot motor [ say 165 degrees] in one second total. How hot is your finger ?

Then do the same thing but take five seconds to do the same. Hotter finger, right ?

My take is that the longer the cooling medium (your finger) is in contact with the object to be cooled, the more heat transfer from the object to be cooled.

Test 2 : Build a ten foot by five foot bed of hot coals.
Walk (very !) quickly over them. I'm sure you've seen this done on some TV show or something. Feet maybe warm.
Now take ten seconds to do the same. Feet VERY HOT !

Again, the point I'm proposing is that the longer the cooling medium is in contact with the object to be cooled, the more heat extraction takes place.

QED

Now go eat some french fries

I completely agree!

[egneg]

Wrong! Higher flow carries the heat away faster. The greater the delta the more efficient it will be.

[keithbradley]

Well it's raining & I'm bored so I thought I'd jump in to this discussion again with my latest thoughts. I have some boats with high flow rates & some with slow rates & I'd really like to learn more about what's most effective. I'm not sold on the french fry experiment application logic to water-cooled boat electronics ( and what a waste of a good french fry) ! What, at least in my thinking, is most important is the transfer rate between the heat source and the cooling medium which is critically tied to the contact time between these two.

Here's my lab experiments ( perform these at your own risk) :

Test 1:
Run your finger over a hot motor [ say 165 degrees] in one second total. How hot is your finger ?

Then do the same thing but take five seconds to do the same. Hotter finger, right ?

My take is that the longer the cooling medium (your finger) is in contact with the object to be cooled, the more heat transfer from the object to be cooled.

Test 2 : Build a ten foot by five foot bed of hot coals.
Walk (very !) quickly over them. I'm sure you've seen this done on some TV show or something. Feet maybe warm.
Now take ten seconds to do the same. Feet VERY HOT !

Again, the point I'm proposing is that the longer the cooling medium is in contact with the object to be cooled, the more heat extraction takes place.

QED

Now go eat some french fries

Tony, I dont understand how you relate hotter finger/feet, to better cooling. If you were trying to figure out the best way to heat the water coming out of your boat that logic would make sense, but youre not. The idea is to cool the electronics, not heat the water. The slower the flow, the hotter the water will get. Thats what your experiments confirm. I would assume we all knew that though?

The water is ALWAYS in contract with the item that is being cooled if the flow is good and there is some backpressue there. You are not removing your finger from the motor as you did in experimnet one, you are simply applying constant COOL finger, instead of allowing your finger to heat up and the cooling effect from your finger to diminish.

Look at it this way. Take your same coals, lets say they are 200 degreees. Put them in a pan with a little bit of water in it. Lets say that water is 70 degrees. The coals with heat the water, and water temp will rise. Coal temperature will drop, until they meet at a given temp (lets say 150 degrees, just picking a number). If this were done in an insulated situation, where there was no outside cooling source (like cooler air), and cooling was only dependant on the water, the temp would never go below 150 degrees.

Now take another set of 200 degree coals, in an identical pan, except this pan is plumbed to have a constant flow of fresh 70 degree water, in one side of the pan is a water inlet filling it, and an outlet on the other side letting water escape at the same rate so the pan doesnt overflow.. The water leaving the pan WILL BE COOLER THAN 150 degrees. The water doesnt sit in the pan with coals as long, so a given amount of water will not have absorbed as much energy. It doesnt take a leap of faith, however, to agree that this setup will cool the coals beyond 150 degrees, and eventually all the way down to 70 degrees.

Heres the moral: In these two situations, lets say the pan held 1 quart of water. The quart from the first example where the water sat in the coals would contain more heat energy per quart. HOWEVER, if during the course of cooling in the second example, you pumped 10 gallons through, while the temperature would be lower in that water, it would contain more energy (since it removed more), but since it takes more energy to heat a larger amount of water, temps would be lower.

SO...slower flow is a better means if your goal is to have the hottest water coming out of your boat, but faster flow will keep the largest constant temperature difference in your cooling system, netting the coolest components.

I dont think anyone is arguing that leaving the water in there longer will heat it more. If the opposite were true our real problem would be too fast of flow would heat the lake.

One more thing...if your motor and coal examples proved better cooling, why move water at all?

[properchopper]

Wow, my head's starting to hurt thinking about this. Im not advocating not moving the water at all, I think you know that. Simply that the water/motor interface needs sufficient time for heat transfer to equilibrate. In my model I'm assuming that, in an imaginary sense, a "slug" of water enters the cooler, heat transfer/equilibration takes place, and then the water is discharged, and a fresh slug of water enters, and on and on. In my way of thinking ( and I got a D in Thermo in college BTW ) , the length of time the slug stays in place is critical for maximum transfer to take place. In actual application, the rate of (continuous) flow is likened to the latency of slug enter/stay/exit. I think I'll go sharpen some props

[Rumdog]

WE're not trying to transfer heat here. Keeping the coolest water possible on the esc and can is the best way to keep the item cool. Allowing the water to warm is just allowing everything to warm. This is why when I run in ice cold water min the winter my components run cooler than in a warm pond in the summer.

[forescott]

I just wanna see someone walk over a bed of hot coals in the spirit of this thread!

[keithbradley]

Wow, my head's starting to hurt thinking about this. Im not advocating not moving the water at all, I think you know that. Simply that the water/motor interface needs sufficient time for heat transfer to equilibrate. In my model I'm assuming that, in an imaginary sense, a "slug" of water enters the cooler, heat transfer/equilibration takes place, and then the water is discharged, and a fresh slug of water enters, and on and on. In my way of thinking ( and I got a D in Thermo in college BTW ) , the length of time the slug stays in place is critical for maximum transfer to take place. In actual application, the rate of (continuous) flow is likened to the latency of slug enter/stay/exit. I think I'll go sharpen some props

The problem with all of this is that people seem to be missing the fact that there is always water there. People are thinking that water has to be there for a certain length of time, not realizing that water is ALWAYS there. There is no time where the cooling system is without water...its constantly being cooled (If there is aeriation that is a completly seperate problem), either by cool water, or by warm water. Keeping the same water there longer and allowing it to heat provides no advantage. Heat energy is like anything else, it will naturally seek an equalibrium. The cooler the water, the faster the heat flows to it, period. Its just the way it is guys.

[Brushless55]

WE're not trying to transfer heat here. Keeping the coolest water possible on the esc and can is the best way to keep the item cool. Allowing the water to warm is just allowing everything to warm. This is why when I run in ice cold water min the winter my components run cooler than in a warm pond in the summer.

Yes

The problem with all of this is that people seem to be missing the fact that there is always water there. People are thinking that water has to be there for a certain length of time, not realizing that water is ALWAYS there. There is no time where the cooling system is without water...its constantly being cooled (If there is aeriation that is a completly seperate problem), either by cool water, or by warm water. Keeping the same water there longer and allowing it to heat provides no advantage. Heat energy is like anything else, it will naturally seek an equalibrium. The cooler the water, the faster the heat flows to it, period. Its just the way it is guys.

and Yes

I think some are forgetting the fact that there is constant water contact with our systems (heat transfer)

[785boats]

Well after absorbing the info on this thread from you guys that know heat exchangers, & after a long discussion with a new member at our club who also designs heat exchangers for a petroleum company, I have to say that I am a convert to the 'More is Better' philosophy.
He went into the laminar flow & turbulent flow with their corresponding heat transfer co efficients & even into the Reynolds numbers of the drag on the water.( he lost me there a bit) & lots of other stuff too, but the outcome is that I'm a convert.
But as others have said, if cooling is becoming too critical in a boat, the setup & prop choice needs to be looked at.
We've got to remember that heat is a by-product of the electrical work being done by the components. If they are being over worked they will break down. Cooling or no cooling. Just like us really
Cheers.
Paul.

[TotalPackage]

All of its a funny debate coz as far as electrics are concerned when the motor is set up right it will like a little heat the batteries too. Whats critcal in my opinion is the esc coz it is the one thing that Truly performs better cooler. If the setup is efficient the motor should not go crazy on heat anyway. With electrics it seems to me all you cooling is the waste you need an efficient set up from the get go . Who cares how much you cool it if you real hot with the electrics the you real wasteful. Most people probably get too hot coz the dont have the headroom in batteries or the motor considering the WORK they expect. Ex. a 1527 is a popular motor for scale guys it surges around 4500 watts or 6 hp but in truth they should want maybe a 2215 with 8000 watts and the batteries to support it. We look at peak specs and say wow but they mean diddly squat you should want rms power anyway. Most of us including my self are fooling ourselves coz to support 8000 watts in batts and a motor that will produce it IS EXPENSIVE so if we can abuse a motor and put a water bandaid on it we do. Thats my take.

[ReddyWatts]

I think the misconception that a slower water flow rate produces better cooling came from the auto industry. Engineers place a water restriction where the coolant exits the block. The water pump was placed at the intake of the block, this raises the water pressure between these to points and raises the boiling point of the fluid inside the engine. These engines run close to the boiling point and needed more margin. If water boils inside the block it drastically lowers the heat transfer rate.
Mechanics thought the purpose for the restriction was to reduce the flow rate and the MYTH was created. It is still believed by many.
We are not running close to the boiling point in our cooling systems and do not need to raise the pressure. Let the water flow freely for the best heat exchange rate. Do not slow it down to a trickle for better cooling as some have suggested.