big problem with cavitation

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Fluid
Boat is 28 total. CG then is about 7.8. Added 2 oz weights in cockpit.
Before writing to you, I already brought up the OB 1/4 inch on the transom because of the problem.
What do you mean by pinning the prop? When on the water, how do I get it on plane?
I am very new to boats and you have been great. I hope rain will stop today so I can go try the changes.
Thanks

[jkflow]

You throw it into the water with forward momentum. Might get it over the critical issue that you are experiencing.

Lower your prop first and see if that helps.

Launching:

https://www.youtube.com/watch?v=5iMJz9ZXTf0

[dasboata]

those shafts are squared ends ,,to me it's a mechanical problem like a slipping shaft , take apart the lower unit !!

[NativePaul]

2s and 90A isn't a lot of power for a 28" boat, especially an ex nitro conversion which typically will be heavier than an electric boat.

Also with 3650Kv on 2s with a 40mm prop, I doubt you are using the full potential of your setup. While it is impossible to say for sure without any temperature data or datalogs, I suspect that you may have some headroom to prop up with. Next time you run measure the temps and if they are significantly under 140 battery, 160esc, 180motor, I would buy a 42 and a 45 mm prop, try the 42,take temps again and if still cool enough try the 45.

[JestDanny]

I think you are way under powered, power to weight ratio, just not enough power, under powered over proped? Starting points, 28 inch hull 30% CoG = 8.4 inches from stearn. Prop ride height, bottom prop shaft = bottom of sponson + 1% to 2% negitive trim angle. Try smaller prop unload engine more 38mm x 1.4

[JestDanny]

What motor is in that OB? need specs. 36x50 mm or 3650 kv?? Recomended motor out runner 35 x 48 mm, 1500 kv, 2S with X440 prop = 14 mph on 3S = 21 mph ???

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Jkflow
Never knew it mattered how you put it in water. Been putting it in motor first. What do you mean lower the prop? Do you mean the entire outboard or angle the prop upward?
Appreciate the video!!

Dasboata
What do you mean by shafts are squared ends?
The OB cannot be disassembled. But the shaft and drive dog are secure.

NativePaul
I will begin a datalog. I have a 40mm prop now. I will also try the 42mm and 45mm props once they come.
OSE said my 3650kv should only use a 2s.
The battery and wires do get hot. What would cause the heat?

JestDanny
OSE said my Leopard 3650kv should only use a 2s.
Where do you recommend buying a 1500kv?
See above for my props

Thanks

[boredom.is.me]

I dont think your 3650kv on 2s is ideal, but changing it wont fix the issue here. Keep what you have and focus on the boat itself. Just as Paul said, you probably arent even using what it had to offer.

[JestDanny]

Leo in-runner 28x45mm 3650kv motor is that correct ? Have you tried running with the CoG at 30% from rear yet, once set leve it there, any improve mints. next set prop ride height to a base line setting, test it an make changes from there. one at a time an test it. I like starting with small prop then seeing how big I can get away with.

[NativePaul]

Other than 2s you haven't said what the battery is, but if it is getting hot it means that I was wrong and you don't have leeway to prop up with your current setup.