comparing water pickups

[Heaving Earth]

I think most of us still contributing to this thread are on the same page. Ive noticed the others that didn't agree with us have nothing else to say.

[Cooper]

Ah little off the op's topic but,, a lot of minor things have been taken as advancements in speed, cooling, control, ect not doing much. But the addition of manny little advancements improves the end result with great results. Just imagine how much better off those that were actually lowering their effectiveness would have been if they were not restricting themselves with inaccurate knowledge passed down from someone that may have had better results from something they did but not realizing just what it was that accomplished this. Then passing that information down to another lesser experienced fellow which in turn advanced themselves ending in reinforcing that concept but still not realizing what was working and most importantly why it was working. In a nut shell practical applied redneck physics. And I'm a redneck so not addressing anyone particular. No one likes to be wrong, but everyone could benefit to be corrected by someone that has correct information- not to be confused with someone who is right.

[TheShaughnessy]

So 600 grit on the bottom is slower? It always seemed like smoother would/should be faster but I bought into the whole break surface tension idea of having it slightly rough, 600 is still pretty smooth. What about carnuba wax and water sticking to it?

Have you guys seen those inline water coolers that kintec sells. Those are just aesthetic right? Unless they were in an ice bath I don't see how they could cool the water without airflow or even with it , to below lake temp.

[runzwithsizorz]

Say you were running a fever, would you apply a cold washcloth to your forehead every 2 minutes, or every 15 minutes? Now imagine being told that you should leave the washcloth on longer so it could better transfer the heat, how would you respond?
Yeah, I thought so. I got yer physics right here baby.

[Heaving Earth]

Say you were running a fever, would you apply a cold washcloth to your forehead every 2 minutes, or every 15 minutes? Now imagine being told that you should leave the washcloth on longer so it could better transfer the heat, how would you respond?
Yeah, I thought so. I got yer physics right here baby.

Is this s trick question? Lol

[h2o 1]

Have you guys seen those inline water coolers that kintec sells. Those are just aesthetic right? Unless they were in an ice bath I don't see how they could cool the water without airflow or even with it , to below lake temp.

These inline coolers were originally designed for nitro. They are fuel coolers.

[Cooper]

Yes 600 is pretty smooth, but 5000 is smoother. I don't know why anyone thinks a rough surface would be more aero/hydro dynamic than a smoother surface. Why not have square ball bearings? Instead of round ones?? The balls inside the actual bearing. It's just that simple smooth is less restrictive period. No debate, no compromise, again got to get back to just can't debate or argue with the laws of all things physical and the way they interact. Hey whatever floats yur boat :). In reality for our boats, a real shiney highly polished hull vs a scuffed 600 grit bottom- it's not really gonna make a difference. Way way too small of a factor amongst the many other contributing factors.

[ManuelW]

As an engineer I can definitely agree to the debate that more flow = better cooling.

For the smooth vs. rough surface I may add an idea to think about. On something that comes in contact with water I'd agree with smoother = better, unless very slow speeds when you can minimize drag for example with shark skin surface. But when air comes into the equation I'm not that sure any more. For example for a catamaran, in perfect conditions it should almost completely float on air with hardly any water contact at all. Might there be a little rougher surface better to keep an air cushion at the steps? Same for props, do we may want with a little scuffed surface that they also take some air into the water to minimize drag?

I've never done propper comparison testing but for my SAW boats I prefer props with a finish as it comes for example from Andy Brown without further mods, same for my underwatership at catamarans scuffed with some fine sanding grit.

regards,
Manuel

[Heaving Earth]

I always leave the trailing edge of my props rough. I use 320 or 400 grit. I feel that, that side is the side that grabs the water and throws it, so if it's rough it will grab the water better.

[Cooper]

I understand the logic of thinking the ruffed up prop will grab the water. But, I have to state what no one has said (many because of the obvious) but the prop is basically the whole thing that is ruffed up. It can't get more ruff than the whole prop, it's what is grabbing the water. It's the whole mechanical delivery of the system, just think of the area that you ruff up, now take a step back and realize the whole function of the prop is "grabbing" the water. It's likely defeating the characteristics of the design of the prop in its entirety. Cupping , changeling the pitch or rake would be the mechanical thing to change. Again when acceleration is needed then a ruff surface might help, sacrificing the design functionality of the prop but in that slight advantage if it works. If this were to be true then the millions of dollars spent in cargo freighters, tugs, ect research and development that industry is and has been advancing in the wrong direction. Reason said, slow turning prop. I guess it could be related to the debate with f-1 cars. They ran grooved tires, not for more traction but to slow them down. And again if this were true why doesn't NASCAR use knobbie tires? They have more traction, all high end sports cars come with threaded tires. ( yes I know it's surface area to be optimized, but point made. And just look at our big brothers, the full size boats, smooth, highly polished, super square edge, super sharp props with highly polished hulls (bottoms-not just the topside).

[tlandauer]

In FE world, the cooling is an open system, cold ( depending on ambient temp) water is constantly picked up and run thru the ESC and motor, there is no need for water to go thru ( hence take the time) a radiator to transfer ( dissipate) heat. There should be no arguments on that. Ambient water will cool, even at 90*F will still be a help to cool . The INCOMING water is always at that temp as long as the water is pickep up.
In an automobile, the cooling system is a closed circuit system, once the thermostat is opened, the only means to cool down the coolant is thru the radiator, and that is why there are tubes and fins to help dissipate the heat. That takes a certain time for the coolant to flow thru and heat to be dissipated. Otherwise the radiator could be just a water tank. If we can provide ambient temp coolant while the car is driven, there would be no need for a radiator! All that is needed is to restrict the flow so an efficient temp on the engine is maintained.

[Cooper]

Well said. I had a small 21' ski boat, did that have a thermostat on it? I know it didn't have a radiator, like above stated no need for a radiator. (Or the conspiracy theorists may say they aren't allowed to have radiators because of the possibility of antifreeze getting into the water and contaminating the water!!! Lol!!!!!).

[tlandauer]

I guess the question here is that would a finned motor can under a water jacket be more efficient in dissipating the heat than a smooth can? And if so, would the flow of water be slowed down a bit? Would the slowed down flow cancel out the benefits of the more efficient fins?
Same goes to the design of the ESC cooling plate: should there be internal fins to increase the flow-thru area?

[Cooper]

Yes finned would be a benefit, there would be more surface are to exchange heat, more hot metal for the water to pass over.
Think of a one inch sugar cube- having a total surface area of 6 square inches, cut it in half and you add two more square inches of surface area. Now to the extreme crush it up to microns and possibly have a football field sized surface area.

[runzwithsizorz]

More redneck physics in regards to water pick-ups, and Y splitters. I have an amp hungry mono with 4 pick-ups, 2 rudder, 2 hull. Using a 2 to 1 splitter,(not 1 to 2), I feed the ESC with a rudder, and a hull pick-up, and same for the motor.
I do this for 3 reasons; volume, velocity, and consistency. Volume; 2 pick-ups more water, duh. Velocity; 2 supplies into 1 hose will give you more speed/movement, AND volume. Consistency; Unless your hull pick-ups are mounted right in close to
the keel there's a good chance it will be out of the water with a wide sweeping banked turn, leaving the rudder to take up the slack, and to, perhaps prevent your lines from filling with air. Also, and Jay touched on this earlier, rudder pick-ups
seem to do better at slower speeds. With a 2 or 3 hundred dollar speedo, or motor, isn't a little redundancy worth it?