Water cooling hole

[koolstrike]

Has anybody made the water cooling hole that is in the rudder larger? I noticed today when running at very fast speeds that the water was exiting the side port hole slowly, my guess is that the boat is going so fast that it cavitates past the entrance port.

Also, what is the max temp my 5000mAH battery should run at, after running today the pack had a 140 F temperature.

[Rex R]

140F while a bit warm...it sounds about right, if you ran most of the pack out. you should consider 150F to be an upper limit. I've heard of people enlarging the hole(water pickup), you'll want to do so a little at a time.

[Doby]

Install a metal pickup tube on the transom and stop using the rudder for picking up water cooling. I use a brass tube about 1/4" below the transom and water files out the side about 2 feet !

[Fluid]

While water flying two feet out the exit hole looks cool, it is probably compromising the cooling effectiveness of the system. Water needs some time in contact with the hot parts to pick up the heat, and if the water runs through the system too fast, heat transfer will be too low. As long as you can see some flow of water out the exit, you are probably fine.

Picking up water in the rudder is less draggy than an external pickup tube placed in the roostertail. The water coming off the prop is going faster than the boat is, so the "push" against the tube is very high making high drag. The drag penalty with a rudder pickup is very low.



.

[Doby]

[QUOTE=Fluid;37501]While water flying two feet out the exit hole looks cool, it is probably compromising the cooling effectiveness of the system. Water needs some time in contact with the hot parts to pick up the heat, and if the water runs through the system too fast, heat transfer will be too low.


Motor and speed control always never above ambient on even the hottest day. :bounce: Give me volume of water any day.:banana:

[G Doggett]

While water flying two feet out the exit hole looks cool, it is probably compromising the cooling effectiveness of the system. Water needs some time in contact with the hot parts to pick up the heat, and if the water runs through the system too fast, heat transfer will be too low. As long as you can see some flow of water out the exit, you are probably fine.

Picking up water in the rudder is less draggy than an external pickup tube placed in the roostertail. The water coming off the prop is going faster than the boat is, so the "push" against the tube is very high making high drag. The drag penalty with a rudder pickup is very low.



.

:iagree: :iagree:
I restrict the water flow on my gas boats to improve cooling and use rudder pick ups.
Graham.

[Ctonez]

larger rudder hole, OSE cooling jacket, large bore outlet, and bigger ID tubing made the temps in my SV much lower.
rarely do I see temps above 110.

[Fluid]

Sigh. You can lead a horse to water......
:laugh:


.

[Doby]

Sigh. You can lead a horse to water......
:laugh:


.

.....But if he drinks to much, the horse will run hotter?!?!?:bounce: :bounce: :flame42:

[Eyekandyboats]

you can always push him in.. that should cool him off

[Chop]

This is my understanding of the thermodynamics at work here:

Any change in flow is insignificant, as long as you don't have steam coming out of the exit hole. Basically if you run water through a cooling jacket at 5 ounces per second you will get x amount of heat transfer. If you run it through at 10 ounces per second you will still get x amount of heat transfer, but the change in temperature of the cooling water will be half as much.

The amount of surface area of the cooling jacket would be more critical. This is a “six of one, a half dozen of the other” type of argument.

[Doby]

Hey, sounds as good as any other theory:confused1: . Whatever works.:banana:

[Doby]

you can always push him in.. that should coll him off

I love it :rofl:

[Mich. Maniac]

larger rudder hole, OSE cooling jacket, large bore outlet, and bigger ID tubing made the temps in my SV much lower.
rarely do I see temps above 110.

Could you share how you did this exactly? dud you also drill vertcal part of rudder?

[Ctonez]

Could you share how you did this exactly? dud you also drill vertcal part of rudder?

I'd use a round file to remove burrs or obstructions in the vertical hole, but I find it to be plenty large.
To enlarge the rudder blade hole, (btw - this isn't originally my process, I asked the same question you did and got this info...) use a dremel with a pointy grinder stone...the greenish one and CAREFULLY enlarge the rudder inlet only a slight bit. you could probably use a drill bit, but the possibility for screwing it up is much higher.
use the round file to remove any excess bits/shape the opening, and blow through the vertical hole/outlet to make sure it's all cleared.
My stock rudders came with really small inlets, almost "shrouded" a bit by the aluminum, my intent was to make sure this didn't obstruct any flow to the already smallish opening and then I really only opened it a little more than stock...I can see water coming out of the outlet when I drive the boat by.

I did that with both my SV's (OSE jackets on both as well...I find my boats stay drier and cooler with these), and in my Pmono version (Ammo/Bar125) I use the yellow tygon fuel tubing, but until recently used stock tubing on my stock SV. I could feel much more resistance when blowing through the stock boat...I have since gone to larger ID tubing on the stock boat as well. Gimme a few hours and I'll post some pics...

[egneg]

As long as you have water flow you will have heat transfer. But for every action there is an opposite and equal reaction. At some point you will be creating more drag than what is gained from the increased water flow (the point of diminishing returns). I say minimal water flow to achieve good running temps is all that is needed - after that you are sacrificing energy and speed.

[bonewar]

mich , i,ve drilled out all of my rudder pick ups ,with drill bit in hand and rudder, just ream the hole out very slowly , you shouldn't need to drill the vertical hole , just make sure it is clean , then enlarge all of the tubing in the boat,and exit hole. (koolstrike)I've tried water pic ups on the back of the transom,they worked fine but the amount of water they kicked up was slowing the boat down, I've tried water pick ups in the bottom of the hull , they work as well , but not as good as the pick ups on the transom, so mate in my opinion you are better off with the rudder pick up that has a nice sized hole ,larger size tubing,and very little drag. Ive put this rudder (toysports)-(pics) on both my sv27, and the maritimo its the goods . if your interested i bought it from Andrew at www.fastelectrics.com:rockon2:

[ggcrna]

Where can I get larger diameter tubing?
Thanks,
G

[badag98]

lowes that is where i got mine; I tried the fish tubing from Pet Smart but it was too thick and hard to bend, very stiff!

[ReddyWatts]

Quote: The myth of velocity originated among those unschooled in physics or
thermodynamics, I suppose, because a common racer "solution" is to
press a fixed restriction into the thermostat housing neck when no
thermostat is desired. The conventional (but wrong) wisdom is that
the restriction "slows the water".
In reality, all it does is provide some more dynamic pressure in the
block by restricting the flow. The exact same result could be
accomplished (assuming the water pump doesn't surge or cavitate)
with a higher static pressure (cap pressure), assuming the system
could withstand it.

http://yarchive.net/car/engine_water_restrict.html

Quote: The most common myth is: I have to slow the water down to help it cool. If this is the case; some is good more is better. Just stop the water. As silly as this sounds there people that suggest you do exactly that. Remember what you are cooling. You are not cooling the water you are cooling the engine.If the water was to move too slow or be stopped, it would take no time at all for the heat to be transferred to the water. The best coolant and the best pressurized system will still have a boiling point below 300 degrees.

The higher the water flow the better for cooling. Remember a water pump's job is to move the hot water out of the block to the radiator.

http://www.nhraunleashed.com/profile...ooling-systems

[BHChieftain]

Quote: The myth of velocity originated among those unschooled in physics or
thermodynamics, I suppose, because a common racer "solution" is to
press a fixed restriction into the thermostat housing neck when no
thermostat is desired. The conventional (but wrong) wisdom is that
the restriction "slows the water".
In reality, all it does is provide some more dynamic pressure in the
block by restricting the flow. The exact same result could be
accomplished (assuming the water pump doesn't surge or cavitate)
with a higher static pressure (cap pressure), assuming the system
could withstand it.

http://yarchive.net/car/engine_water_restrict.html

Quote: The most common myth is: I have to slow the water down to help it cool. If this is the case; some is good more is better. Just stop the water. As silly as this sounds there people that suggest you do exactly that. Remember what you are cooling. You are not cooling the water you are cooling the engine.If the water was to move too slow or be stopped, it would take no time at all for the heat to be transferred to the water. The best coolant and the best pressurized system will still have a boiling point below 300 degrees.

The higher the water flow the better for cooling. Remember a water pump's job is to move the hot water out of the block to the radiator.

http://www.nhraunleashed.com/profile...ooling-systems

:iagree:


-Chief

[m4a1usr]

Where can I get larger diameter tubing?
Thanks,
G

I found the Silicone tubing at Petsmart for fish tanks a pretty good deal. The id is .160 and the od is about the same as nitro fuel tubing that is only .125 id. Cheap too. Less then 3 bux for 8 ft. Its not pure silicone tubing though. Its a mix but still has a higher temp rating then the polyethelene found else where.

John

[ncornacchi]

I messed with transom pickups, thru-hulls, boring rudders and finally convinced a friend to make these up. They are the exact replacement fit to the UL-1, but could be made to fit anything...I obviously feed the motor and ESC spearately now. If only I could get the battery temps down now...Motor (1515Y)=temp A, ESC (cc240)=tempB, Batts=temp C

[ncornacchi]

Couldn't upload second pic...happens alot...pic size too large?