Water pickup for a Titan 40

[Ballorshk]

Hi,

Currently I am using the water pick up built into my rudder for the ESC and motor water cooling. But, I am not getting enough water through the boat. She is thermalling lately once a run at the 5-7 minute mark. I am running a Hacker 77, Nemesis 10 XL, 1.5:1 ratio, and X445 prop. Now, granted the water and air temps are warm in August so that will contribute. And generally if I run her 4-5 minutes I am avoiding the thermal shutdown. I am running her with anywhere from 14 cells up to 20, or even 6 S lipos sometimes. 14 cells is not a problem. But, from 16 and up, things are getting too hot. Chris Fine suggested a brass tube water pickup to come off the propwash to get more pressure through the lines. Have any of you put that type of pickup on your Titans, if so do you have any pictures of how you mounted it, etc.????? Or is there a way to maximize the rudder pickup and tweak it to catch more water?

Please let me know. Getting tired of shutdowns. And I gather that over time, this can lead to ESC problems. I usually bring her in slowly once the ESC comes back online and let things cool off before running again.

Thanks,
T

P.S.
I found some 1/4" tubing at Lowe's. But, that seemed kinda large. Any ideas where to get some smaller diameter tubes?

[JimClark]

Tubing can be had at your local hobbyshop or at www.smallparts.com (http://www.smallparts.com).
As far as your setup goes I find it hard to believe you are not getting enough water. I would look at other causes like friction in your drive line too much prop ect.

Jim

[Ballorshk]

The gear meshing is excellent. The trans is smooth. The flex shaft does not bind. And Danny Fine built the boat himself for me. I am really concerned about this.

[F1tunnelhull]

Ballorshk,

firstly what type of rudder - how big is the water pick up hole. I found that sometimes on speedmaster and simular rudders i needed to dremel out the pickup hole and increase the size ever so slightly to get more flow.

Another tip which i have just found useful is seperate water cooling for motor and ESC. I cool my ESC via the rudder and have CA'ed a bit of brass into my trim tab to cool the motor. I also have 2 cooling coils around the motor.

I run a 10Xl direct drive to a M447 up to x450 prop and run 3mins max (as i dont want to kill my cells). Cells are GP 3700's. Everything is cool with this setup.

If you are running a x445 on 14cells and using the same prop on 20, perhaps you might be better of going down a size to something like x442. You may lose a bit of speed.


David

[Jay Turner]

Inadequate water flow is seldom the problem, if you can see a small stream of water exiting the boat that is enough. In fact, too much water flow will inhibit heat transfer; I'd look elsewhere for the problem. First, drawing too many amps will result in heat buildup in the ESC which is beyond the ability of the cooling plates to carry it away. Few ESCs have anywhere near good heat conductance, the cooling is added as an afterthought and is usually of poor design; it is made to fit rather than to optimize cooling. The new flat Hacker 77s are much better in this regard, putting the water flow within 1/16" of the FETs. In contrast, the plates on a Bara125 require some of the heat to travel an inch through the metal before it gets to the cooling water....a poor cooling design (but better than nothing). But realize that watercooling is no substitute for a reasonable boat setup.

Running the same prop on from 14 to 20 cells is likely the chief problem, as suggested go down in prop size as cell count rises. Too many amps for the ESC is not a good thing, and if the standard water cooling won't keep you from thermalling, then you certainly should pay attention to what the ESC is telling you - reduce the amp draw!:eek:


Additional things to check:

Does the cooling water go to the ESC first, then to the motor?
Does the water exit the hull in a small stream or does it dribble out?
What temperature is the motor after a run? Heat will damage it too.
If you are running on a small pond and have to get on and off the throttle all the time, the average amp draw will be high; run on a larger pond, run for less time, or prop down a bit. :).

[D. Newland]

I ran into this at the Sardine race in 1 heat with a very similar setup. IMO It's because your setup is too hot for summertime. If your hull likes the X445, then utilize your geardrive a bit more on the higher cell count runs. Try 1.7/1 on 16 cells, and 1.9/1 or 2/1 on 20. I bet that will solve your thermalling.

[Old Sloppy]

A question, How are the temps of the batteries ?

Hot batteries can indicate an extended high amp draw.

You may at or above the rating of your ESC.

On the water flow question, I am with Jay T. on this. A small flow is enough.

Harry :)

[Ballorshk]

So, from what some of you are saying, I need to think about the following items:

Maybe I am not getting sufficient water flow. With the rudder pickup I am seeing almost no water exit the boat. So, it probably is only getting it on the turns rather than the straights. When I take the boat out of the water and tip it back I get some water running out of the rudder and exit tube. So, sounds like I could try and open up the intake port on the rudder with my dremel, what do you think???? Maybe I should run some wire down the top hole and make sure I do not have any obstructions in the up tubing through the rudder too? The rudder I am using is the FDM kickup style version.

Also, you indicate going down a prop when running higher cells. So, maybe when I am running my 20 cell packs I need to go down to a X442 prop. Or change the gearing to something even more conservative than a 1.46:1 ration on the trans.

You are also saying that my older style Hacker 77 has less cooling properties than the newer flat versions. Guess if this one dies on me I can try the newer version.

The water intake flow first goes into the ESC, then goes into the motor, exits the motor and goes out the back of the boat.

I do run on a smaller pond so I am on and off the throttle quite a bit. So, you are saying run the boat on a larger pond for short durations from 3-4 minutes on 20 cells or 6s Lipos, and maybe I can get longer run times with lower cell counts like 14-16, like 4-8 minutes.

Anything that I missed? Any avenues or ideas I forgot?

Please let me know. My most recent purchase was a Aeromarine water pickup. It is made out of polished aluminum in a curved shape with a nice water pickup tube. I put that on my rudder arm tonight. But, the resistance was slowing the boat down greatly and in fact pushed the pickup arm out of the water. It might work better if I can mount it better, a little farther back from the propwash, and somehow bend the pick up tube without crimping it so it is more like a C shape than straight.

[Ballorshk]

I am not sure of the exact motor, esc and battery temps. I should probably get a thermal probe type temp guage to be sure. Basically, the motor and esc get very hot! Not burn my fingers kind of hot or sizzle spit, but hot for sure. The batteries get hot but I do not think to the point they are getting damaged.

The boat runs best with my current setup when I am putting 16 cells through it. When I put 20 cells in there, she tends to thermal after 2-3 minutes of WOT. I have 6S Lipos the boat runs okay on too. I think because the boat is pushing so little weight they do not make the boat run much hotter than the 16 cell setup.

I tell you, I wish I had the know how to make some kind of contained intercooler system. It would consist of a small battery operated pump, a chiller of some kind, and some fluid that keeps cooler than water. Set that up in there and let it rip.

Has anyone tried putting a small battery operated fan unit inside their boats blowing on the motor and esc?

[Old Sloppy]

The boat runs best with my current setup when I am putting 16 cells through it. When I put 20 cells in there, she tends to thermal

Your setup runs good with 16 cells ?
With a 1.46 gear ratio ?
Then with 20 cells you need more gearing/less prop.
Like 1.90 gear ratio and or x440 prop or a x637 prop.
If I understand your story correctly, you are about to kill your ESC with these constant thermals.

Harry S.