First boat build.....need help!

[rcnewb]

I started my first ever boat build a few months ago. I now have it finished with a couple runs under my belt now. My first run out I got a lot of water in the hill and fried my steering servo and receiver. After getting new parts, I took it back out tonight for trial number two. I have all leaks sealed up. The only thing I didn't do was tape the hatch. There was a little water in the hill, but not to much. After flipping it a couple times, it now is not responding to my throttle. I having steering, but that is all. I switched the receiver to another new one, and that didn't fix it. So now I don't know what to look at next. The boat I am running is a 23" balaenoptera musculus. It is a cheap boat, but its what was available to me. I installed a strut with offset rudder, a leopard 3660 3060kv motor, a turnigy marine 120a esc, and a nano tech 3300mah 3s battery. I know that its overkill for this hull, but I wanted a lot of speed. Now I just need to figure out how to handle it!!! I still haven't gotten full throttle out of it without flipping it. When I take off, the back end goes deep into the water before it actually takes off. It isn't stable at all when it gets on plane and then it just spins around or flips before I get to top speed.

First thing I need help with is why did it stop running? How can I check my components to see what isn't working?
Then I need to figure out what I can do to make this thing more stable for all this power! Im thinking of buying a decent fiberglass hull, but I haven't given up on this one just yet!

Any help would be great guys!

[lenny]

Do you have another motor that you could just hook up to the esc,
To try and see if it responds with the tx ?
That motor you have in it has way to high of a kv for 3s.
3060kv *11.1= 33966 rpm,
And that is one reason it will not run right.
Post some pictures of the boat and the setup in side the hull,
How long did it run for with that setup on 3s ?

[rcnewb]

I will try to get some pictures up tomorrow, and the short video that I got of it as well. I don't have any other motors to test out the esc. It ran for maybe a minute. When it died, it flipped and landed pretty hard. What kv motor would you suggest as a max on 3s? I want as much speed as possible out of this little thing. But I also don't want to burn up any parts. The first time I ran the boat, I ran it for a couple minutes, but the rx got really wet and died.

[siberianhusky]

Any water in the hull is not good. Chances are the esc has gotten wet and died, they don't always fail in a spectacular way.
Try moving the steering servo over to throttle and see if the throttle channel works, if that works it is then the esc or motor, chances are the esc.
I don't think your rpm is way to high, I run 2200kv on 4s with one setup, that's just shy of 32000rpm, pretty common rpm range now. Just have to keep an eye on temps while doing the setup. Start with smaller props and work your way up.
Personally wouldn't change motors just watch the temps.

[rcnewb]

I was under the impression that the esc was waterproof? At least that is what they claim!!! The prop I am running is an x438.

[lenny]

It just sound to me that the boat hull is not handling the setup to well,
Or is just running very wet ?
My 120a Seaking/Turnigy esc get wet a lot in my Rio mod,
But keeps on ticking so far and going on 2 years now.
Still no pictures or video's of your setup yet ?

[rcnewb]

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[rcnewb]

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[lenny]

With the one cell on the port side I would think the CG would be off a lot,
You should move the motor mount back to the stuffing tube and leave a 1/2 gap from tube to coupler.
That stuffing tube and flex shaft is a accident wanting to happen,
We need to see video of how it was running.
Also the water lines on the motor jacket are backwards,
The water should always come in at the front bottom nipple and out at the back top nipple so it over flow the jacket.
This way it fill the whole jacket with water for better cooling.
It is better if you can have the back exit nipple at the very top of the motor.

[twissted]

Before you run. Try the bath tub! Before you go out and make changes that will harm your boat. Then run and make changes that make the boat better. If you took on water, it should have been in the tub with no power.
I hope this helps?
Forget math and the things that will get you confused. Water is a level and will tell you how to get started.
Learn the basics and you will fine that a lot of the problems solve them selves.

[keithbradley]

Any water in the hull is not good. Chances are the esc has gotten wet and died, they don't always fail in a spectacular way.
Try moving the steering servo over to throttle and see if the throttle channel works, if that works it is then the esc or motor, chances are the esc.
I don't think your rpm is way to high, I run 2200kv on 4s with one setup, that's just shy of 32000rpm, pretty common rpm range now. Just have to keep an eye on temps while doing the setup. Start with smaller props and work your way up.
Personally wouldn't change motors just watch the temps.

I agree that the RPM is not out of range, but a 3660 of that kv can pull a lot of current...far more than his ESC is rated for.

The BEC could be bad, but more than likely the ESC failed. I would replace it with something rated 180A or higher.

[rcnewb]

I have had it in the tub to check for leakage, and I'm good there. I guess I can set it in the water to help balance things out. It actually sits a little heavy on the right side. I do need more weight forward tho from what I've seen of it running. The motor is so far back from the stuffing tube because I kinked the stuffing tube on accident and I already had the motor mounted. I have another tube, I just need to install it. I don't really want to move the motor any further back as I already have to much weight to the rear. Thanks for the suggestions guys. I'll look into a bigger ESC and see if that might help.

[Peter A]

Your motor and esc combo should be ok. The battery is too small in Mah and c rating for the rest of the setup. With those rpms a smaller prop will unload things a little, try something in the 32-35 mm range perhaps. The setup would be better with the motor moved aft and putting the battery forward will centre the weight in the hull and allow you to adjust the c.o.g. I know that it's a bit of a hassle to change but it should be worth the effort. To be fair putting a bigger esc in that small boat is not going to fix the problems.

[rcnewb]

I will have to try and make a new mount to move the motor. Not to big of a deal. The only reason I put it there is that is where the original mount is for the boat. I will try a smaller prop and move some things, but first I have to figure out what died and why. Being new to this hobby is kind of testing my learning. All these parts I purchased without any know-how on what goes with what. I still don't really understand what motor, ESC, battery combo goes with what. How do you figure things like that out? I guess trial and error is good in a hobby like this! Thanks, I'm still trying to get a small video up of this running. Hopefully I can get her going again for some more video.

[rcnewb]

So last night I was just messing around with the boat, trying to figure out where to move things to. I decided to plug it all in and see why it wouldn't run. Well, it started up! I'm all kinds of confused as to why it wouldn't work up until now. But its running again, so I'm going to fill up the tub and look real good and hard for leaks. Then I'm going to move the motor back a little bit and the battery forward a little bit and see how my COG is. Hopefully I will be able to run it again this weekend and get a video of it up on here. I don't have any other props at the moment, but maybe I'll run to the hobby shop and see what they might have that I can try that is just a little smaller.

[Southwest]

You know what you should do is mark on edge of boat the 30 percent which will be Center of gravity. Next take motor out and lay motor at 30% mark and place single lipo in front of motor and place esc on top of motor. Lift boat up at 30% mark with finger tips and see how it balances. Some say stuffing tube should be 7/16" from coupler as I see your cable is 3/16" in diameter. I have many boats that size and my m/mount is at 6" from transom with lipos on each side of motor for balance at 30% with a 632 s & balanced with a touch of negative at the strut for flat running.