New stock UL-1 pulling 70-90 amps-- HELP!

[MT-Tank]

( I am a Newbie with approx 30 runs with Blackjack 26)

Just got my new UL-1 two weeks ago. First run in local pond destroyed the prop on a submerged object. Just installed the replacement prop (from Tower) and an Eagle Tree data logger. Two runs on a wide open lake and my batteries were 150 deg F, motor 150 F, ESC 120 F. Batteries are Rhino 4900 20C, brand new.
Data logger showed typical wide-open 65-75 amps, occasional bursts to 85-95 amps. Manual states that 60 amps with bursts to 70 should be the max!

Is this the correct prop?
AquaCraft FRP 3-Blade 40mm Prop (2) SV27
I did clean up the flash and edges on the prop but did not balance it. Do plastic props need balancing?

Is there such a thing as too much grease (blue GrimRacer) on the flex cable?

No other mods except the replacement water jacket.

Thanks!

[Ub Hauled]

that amperage is too high...
is the boat running wet?
Make sure the prop spins freely and that there is a good gap between the
drive dog and the strut.
Keep in mind that lower C batteries will give you more heat/demand.

This is the recommended prop as per Aquacraft:
UL-1 Superior L40x57/3 AQUB9760

Plastic props give, therefore not perform well... there is also the M445 from Octura, seems to get peoples cost/fun factor in check... but I would not get a bigger prop.

[LiPo Power]

I had my new UL-1 on water last saturday with Grim 40x52/3 prop and no temp issues. I have try 2 x Thunder Power, 40C, 7.4V, 5000mAh and later 2 x Zippy 5000mAh, 20C, 7.4V. No temp issues at all. Highest temp was 113F on ESC after longer than normal run using TP batteries.

[Fluid]

Boat setup can make the difference in amp draw, and run time has a huge effect on temperatures. What is okay for a 2 minute race can cook everything if you run for 5-8 minutes. Frankly I have seen a number of UL-1 setups draw more than 60 amps with good cells; good cells will deliver more amps for more speed and more heat. Guys in the club run Rhinos like yours with good success, but only for 2 minutes at a time.



.

[LuckyDuc]

Check to make sure that the strut bushing is spinning free. Most come with it jammed into the stuffing tube and need sanding to loosen them up.
The amps are comparible to what I was getting with my Eagle tree. The batt and motor temps are high though. How long were you running the boat?

[TCR]

I too would run the 40x52/3, my 40x57/3 boats all run hot w/ high quality cells. Plan on burning up your capacitor on your esc (put new caps on now if you can). See the capacitor threads for instruction. It's sad we have to do this to new boats, but I've managed to burn up 2 out of three ESCs and one motor on very new UL-1s. Upgrade your ESC and move on is my opinion. Did you not get the memo that these UL-1s are only designed for 2-3 minute run times, any longer and your going to blow up the electronics?

[LuckyDuc]

FWIW, I run 6600mAh 4s in my boat (3 x 4s 2200mAh in parallel) and only get 3 minute runs before my packs are drained (resting voltage of 14.8-15v). Most race oriented FE boats have power systems that are designed for maximum power output for 2.5-3 minutes. The average heat race only last 2-2.5 minutes. The UL-1 is marketed as a NAMBA and IMPBA competition model, and has a power system to fit that niche.
My EDF jets only get 4 minutes of flight time, and my Trex helis only get 4.5 minutes of flight time before the packs are spent. That is the nature of high current electric power systems. Yes, you can prop or pinion down to increase run time, but most don't want the loss of performance that comes with that... hence the shorter run times.
I have an ETTI 150 ESC in my UL-1 now, and it too will blow caps if I run too long, or at less than full throttle for long periods of time.
BTW, there was no memo about the run times just basic power usage math.
If you have a 5000mah pack, and drain it at an average rate of 90 amps you will only get 3.3 minutes of run time. ( 5 amp hour x 60 minutes = 300. 300 divided by 90amps = 3.3 approx minutes of run time)
If you use a grim 40x52/3 prop and take a break after 3 minutes of running to let things cool down, you could get a second 2-3 minute run in with out straining the power system.

[TCR]

Honestly, do you really feel the electronics are up to par for a RTR AND the type of people who buy RTRs? This has been beat to death on other threads(the UL-1 and it's weaknesses). I've got plenty of cash for RC boats, but don't have the time it takes to build a quality model, so I rely on manufacturers. I'm not trying to make excuses for those of us who are less experienced, but I've had quite e few RTRs in my day that don't require all the repairs and mods as these Aquacraft models do.

[LuckyDuc]

The only issue I had with the original electronics was the 14 gauge wire they used for the battery and motor leads. It is too small IMHO for the current load and tends to melt the solder at the connectors. Other than that, I didn’t have any issues with the electronic side, and I ran very aggressive props for 2.5 – 3 minutes.

Regarding your question… “Honestly, do you really feel the electronics are up to par for a RTR AND the type of people who buy RTRs?”

In my opinion, yes, because many did not have issues with the stock electronics. Me included, and I really stress tested my ESC with aggressive props. I do feel bad for those who have fried ESC’s. It may have been a QC issue, or a usage issue. That is not always clear. Hopefully those who have issues with the ESC are getting replacement units from AquaCraft hobby services.

I’m very skeptical of RTR models, as I have been burned with RTF airplanes in the past. Many of those come with absolute junk electrical components. This RTR didn’t give me any issues like I’ve seen with other RTF airplane kits, so I’m impressed with it. Perhaps my expectations are low. I did have issues with the turn fin and water jacket, but I believe that those have been addressed.

Regarding the “type” of people who buy this particular RTR boat, I’m not sure that there is “one” type of person. In fact, many of the experienced FE boaters in my club bought one, and they are far from FE newbs.

[MT-Tank]

What I have learned so far and what I still need

What I have learned so far:

• Rhinos are good batteries (10 gauge and they barely fit!)
• Long runs accumulate heat. Just because the system can handle the load doesn't mean it can handle it for 6-8 minutes.
• Grim 40-52/3 may be better for sport and 40-57/3 may be better for short races.
• Check strut bushing and spacing

What I still need to learn:

• Do I really want a gap between drive dog and the bushing? This would put all the thrust load on the stuffing tube and motor mount rather than the strut and transom.
• Will check the bushing this weekend. The boat is at the lake house.
• Will try taking off the silicone tubing acting as a water seal on end of the stuffing tube. It only had a 'little bit" of friction on the flex shaft but perhaps it is the problem? (Woke in the middle of the night when I remembered that one 'modification'!)
• Did Tower send me the correct replacement prop? I never read size off the original before I lost it. Anyone still have their original prop?
• Need to re-read the sharpening instructions to work the new props (when I ever have time...)
• will read capacitor threads
• Can you put too much Grim grease on the shaft?
• Would balancing a plastic prop make a difference?

Thanks!

Paul

[LuckyDuc]

* Long runs accumulate heat. Just because the system can handle the load doesn't mean it can handle it for 6-8 minutes.
That is correct.

* Grim 40-52/3 may be better for sport and 40-57/3 may be better for short races.
I would say that the 40x52 is a better heat racing prop as the hull is more stable in race water conditions, and the 40x57 is better suited for higher speed sport fun in smooth water conditions.

* Check strut bushing and spacing
If you have binding I would say that is the first place to check.

* Do I really want a gap between drive dog and the bushing? This would put all the thrust load on the stuffing tube and motor mount rather than the strut and transom.
Yes. The general rule of thumb is that the gap should be the same as the diameter of the flex cable, however I run mine closer to the strut than that with out any issue.

I never read size off the original before I lost it. Anyone still have their original prop?
I don’t, but I believe that it is a plastic version of the 40x52/3.

[Ub Hauled]

What I still need to learn:

• Do I really want a gap between drive dog and the bushing? This would put all the thrust load on the stuffing tube and motor mount rather than the strut and transom.
  
  Absolutely! Friction at the strut/drive dog is a huge burn factor, depending on how close you are you can get huge amp draws, burned motor/ESC or at least a broken shaft. The flexshaft twists and contracts, that's why.
  
• Will try taking off the silicone tubing acting as a water seal on end of the stuffing tube. It only had a 'little bit" of friction on the flex shaft but perhaps it is the problem? (Woke in the middle of the night when I remembered that one 'modification'!)
  
  Should not be the problem, lots of boaters do this to avoid water inside
  
• Did Tower send me the correct replacement prop? I never read size off the original before I lost it. Anyone still have their original prop?
  
  Not sure but the prop I posted is the correct metal prop (you should be using metal props).
  
• Need to re-read the sharpening instructions to work the new props (when I ever have time...)
  
  Sharpening and balancing is important, it'll diminish heat and up speeds.
  
• Can you put too much Grim grease on the shaft?
  
  No. once you insert whatever is excess will be rubbed off in the insertion process, just make sure you clean the old stuff every time.
  
• Would balancing a plastic prop make a difference?
  
  No. Get metal props.
  

Have fun Paul...

[LuckyDuc]

You might also consider picking up a thrust bearing to install between the collet and the motor. This will reduce the thrust force on the rear motor can/bearing. OSE sells a 5mm one that works well.