Swampdawg67

Hi guys, first time posting. Really need help. Have a ply outrigger boat that won't get up on plane. Approx 750mm length. Not sure exactly on motor size but 540 size 3500kv, 90a turnigy esc, 3s batteries various mah with 65-130c turnigy nanos, x35 prop. Weight about 2kg with biggest bat.
I've read different things like lower Kv with more volts. Any help on a better set up or some guidance on this is appreciated
Cheers

Got RPM

There are many reasons why a rigger won’t plane. A few include:

1) Your prop is small for a boat that size, but adding a larger one like an x440 or x445 will likely over-stress your ESC.
2) Is the rigger a proven design or a home-design?
3) Was the rigger designed for nitro or FE?
4) Where is the CG relative to the back of the sponsons?
5) How deep is the strut centerline relative to the bottom of the transom?
6) Is the strut flat or angled down relative to the bottom of the tub?

You can try tossing the rigger forward onto the water surface with the motor running full on, some older designs require that technique to get on plane. We really need more specific information about the boat, and a few pics of the transom and interior layout will help us to help you.



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Hydro Junkie

3500 KV could be part of the issue as well. We use 850 to 1200 KV motors in 1/8th scale hydroplanes and they plane out very quickly using a 57mm prop. I know your boat is smaller so I could be wrong but, then again............

Got RPM

A common power system for a ~30” rigger is a 36x75mm motor with a Kv between 2000-2400 spinning a 45-48 mm prop on 4S. The biggest issue is the ESC rating, although running 4S will reduce the amp draw significantly with a lower Kv motor.

The OP hasn’t been back since he posted so we still need some additional information.





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Hydro Junkie

So I could be correct, that's actually a relief. That is why I made sure to point out that the motors I'm familiar with are for a boat that's in the range of 41-44" and weigh considerably more than his rigger. What I find interesting is that his rigger weighs only a pound less than my sport 20 Pay'N Pak. I don't know if his boat is heavy for its size or if mine is light.

Swampdawg67

It was working ages ago but it keeps cooking batteries. I left it for a few years. Only change now was a 3660 size 3500kv from a 3050kv. Tried 7.4 to 11.1v various mah and C rating. All puffed up bad plus very hot. It's a R2 marine kit pre installed shaft etc. Just like to know where it's going wrong and a possible suggested set up to try from. The original set up was my own pick of parts based on searching and reading. So it was by no means correct in the first place

Got RPM

That motor should not overheat on just 2S, so there may be a additional issues. What is the LVC set to? Do you run until the LVC kicks in? Cells will puff when they overheat or are run down too far, or both. I’m surprised the ESC has survived frankly. I’m not familiar with the boat so a few pics would help, as would answering all the questions in post #2.

Overheating on 2S - does the boat actually plane, or plow? The motor could just be defective, and a 3660 is a bit small. I would recommend a 36x75 mm motor with a Kv of around 2800 for 3S running. That should also allow a larger more efficient prop to be used safely.



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Swampdawg67

Got RPM,
i don't think I can post pics yet. Is that right? I replied with a pic of the rig but it said you can't post URLs until you have 10 posts or something?
I'll attempt to reply to some of your questions here if I haven't yet.
CG 3" back from sponson
strut cl 1/4-5/16"
strut almost horizontal
it did get up on plane with a throw launch and went well. I'm using a basic wheel radio until I get another new computer wheel radio soon so unsure what lvc was now. Original computer radio is dead.
I have got a new 3665 2400Kv brushless motor but not water cooled. Think I'll start shopping for new set up you mentioned as a start. What mah and C rating is good for a 4s in this.

Got RPM

The LVC is set in the ESC, not the transmitter. The ESC instructions should explain how to set it. As for batteries, a decent 4S/5000 mAh with a minimum 45C should work, if it fits. I haven’t used them but the Turnigy nanos have a pretty good rep.

The CL of the strut is only 1/4” below the bottom of the tub? Sounds odd, a pic will help. To post pics, go to the test forum below and make enough one-word “test” posts to get your total post count above 10.

https://www.rcuniverse.com/forum/test-posting-forum-72/


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Swampdawg67

Hi guys,
Thanks for your inputs over the last month. Sorry I didn't respond sooner.
I ended up getting 4s 4400 nano battery, 120a esc, 3665 motor 2100kv (already had it). All from your suggestions to start with. Only thing I didn't check was prop size. And a few failed attempts to get on plane. I found a 38mm prop in the spares box. And finally it got on plane! Even when you slow down it'll get back up again. Got several good runs before it cut off. Awesome to see it in action again. Opened up and everything is fine. Not hot or puffed up. It's not a100% set up yet but I'm waiting for 40 & 42 mm props to arrive. Then hit the lake for tests. I'll try posting pics again.
Thanks again

Clugh

Know this is an old thread but have you checked the drive train for drag. Also did you leave it in place while you stored it. If you did this really isn't ideal as the cables form a memory or sorts.

Regards,
Hugh