Need Help. Screaming motor full throttle not possible

[HeineDenmark]

Just ran the first test today on my Brushless Venom Segad 55” build. Specs is: 800KV motor, 320amp esc, 12s battery (2x6s), 56mm 1,4 pitch prop.
This setup was fine but only 98 km/h. The motor and esc didnt even get warm at all.. then i tried the big 67mm 3 blade gas prop. Reached 116km/h but was not able to get full throttle because of the system stalling. Sounds like the motor makes a scream and the stalls. Maybe the prop is a bit to big. But another thing i saw was the prop depth. Looks like it could be raised a few mm up. The motor and esc still does not get warm at all.. Help

[Nevs]

In another thread you wrote about a 67-7-3 prop. Could be a 67mm, 1,7 pitch, 3-blade...Way way to much on 12s/800kv. You probably have peaks at 400-450 amps.

[HeineDenmark]

Okay thanks. Found a 3 blade 58mm prop 1.4pitch. Think i will try that one. I may go up to 15s..

[Nevs]

A few years ago I ran 2x sss 5694/730 kv/8s in a MHZ loose Cannon dragster with a pair of 58/1,4/ 3-blade. Peaks were 120 amps. On 12s it would have been around 250 A.
But if your cat is not a 20 pound +++ you should be able to get anything between 115 and 135 kmh with the 56 mm prop on 12s. So I would try to trim the boat before adding more power/prop..

[HeineDenmark]

Just uploaded a video on youtube. It’s the first run with a 56mm prop. It actually did not look that fast but the gps said 98 km/h.
Link below:

https://youtu.be/DqGpuRwtIio

[HeineDenmark]

Btw the boats weight is 19,4 pounds

[Fluid]

Give us enough information to help. What battery are you using...exactly? MAh, C rating and brand/type. Exactly what motor? A 56mm prop is pretty small for a boat that large, it is lokely cavitating, more voltage won’t help that! Include a photo of the transom from the side.

You could try a more appropriate prop like an x470, but it sounds like you don’t have enough battery capacity, the ESZc may be shutting down due to the LVC.

[HeineDenmark]

I think i’ve found the problem. The 67mm prop was too big (not the 56mm in the video). The boat was perfect in the water with the small prop, just not that fast.. i’ll try again tomorrow with the 56mm, and some adjustments the the prop height and angle. The batteries are 2 x turnigy heavy duty 5000mah 6s 60c-120c..
If you see the video it looks like the prop needs to be set a little higher? But im not sure. Right now its a little lower than the bottom with most of the prop under water while planing. So maybe a little higher..

[Speed3]

The 67mm is definitely to big. 98kph with a 56mm is about right for the motor and 12s. That's around 59mph with a 55 inches boat.

[HeineDenmark]

2nd. test just finished. See video link below. This time with a 58mm prop and 15s.. I had to try it :-)
But in the end the prop blew and broke the shaft. So now the boat is docked until i get new parts. I got a 116 km/h reading this time. Think it’s as far as it will go. The rest is up to the fine tuning of the prop hight and angle.. hope you like the video.. BTW my shoes got wet because i forgot my rubberboots😂
https://youtu.be/0T_4tIjd6A8

[Nevs]

12s/5000/60c, (Turnigy heavy duty) will not surwieve more then 5 -10 runs. You would need around 10.000 mah/60c.