Aeromarine 44" hydro

[AntronX]

That is just SO MUCH wire for your setup. I know that the boat is huge, but there has to be a way to reduce the wire.

I can reduce some length, maybe even half it. I am also going to double the wire on battery packs. I am going to run two 10 gauge wires on the batteries. I also just ordered six 1000 micro Farad 50 volt Rubycon ZLH capacitors, to put three per ESC to help out with current ripple due to somewhat high battery resistance and long wire length. I am going with Castle this time, Hydra 120 HVs. There goes my whole "cheap" idea down the drain. I spoke with their tech guy, and he said that 18" of wire is good and extra caps will not hurt and might help. I definitely agree that high ripple could have taken those controllers out. But I am not willing to continue experimenting with Asian ESC's.

All the long wiring probably had as much to do with your ESC failures as any thing else. The datalog is odd looking, where in seconds did the boat get on plane? Your voltage drops of 8 to over 10 volts are huge. Your cells will not last long with that level of abuse.

The boat got on plane between seconds 346 and 350. See that first big spike? That was it. The cells are rated for 60A continuous. I have 14S2P, so that's 120A. High voltage drop may be due to long wires. I have also been told by couple people that A123 cells have higher internal resistance than good quality 30C LiPos. But i still want to stick with these due to possibility of 12 minute recharge after i find the charger that can give me 20A charging current.

I'm not trying to be mean here, just brutally honest. I like your goal of a "cheap" big hydro, but you may have to re-think some of that goal.

Don't feel sorry, i kind of knew what i was getting into. After some some research on these Turnigy controllers i decided that trying to make them work in a big and heavy boat is not going to happen at the power levels i want. This test showed its possibly true, but there were some mistakes on my part as i discussed. To prove that the reason they blew was long wire runs, i would have to get two more and try again. But i really just want a big boat that runs and not to keep experimenting with controllers.

[eboat]

How far down below the bottom of the boat is the center of the prop ??

It may just be the angle of the picture but they look kinda low

The one in my picture is on a 36" hydro and it is just over 3/4 " below bottom of boat

If it is too deep that might be putting alot of the load on your system

[Ub Hauled]

AntronX,
wy did you opt for 2 motors?
I have an 1/8 scale that runs on 1 NEU powerplant and
at fun speeds... was it cost? Cause by now you probably are
getting close to the cost of one HV ESC and a NEU motor.
There are really fast boats that run on 1527 and even on 1521
motors on 37v.
That is a very good looking hydro, once you get it
going it'll look very "purdy".

[AntronX]

How far down below the bottom of the boat is the center of the prop ??

It may just be the angle of the picture but they look kinda low

The one in my picture is on a 36" hydro and it is just over 3/4 " below bottom of boat

If it is too deep that might be putting alot of the load on your system

Its 1-3/8" or 36mm down from the bottom to the center of the props. Props are 45mm diameter. When the hydro is stationary in the water, the center of the props is 2-2/8" under water, so the props are submerged pretty deep. I am now thinking that i should have run the props much higher when testing to keep peak amps down. They were definitely too low because the boat took off very quickly, with no prop cavitation. For my next test with better controllers i am going to do these changes:

- Test with less volts (maybe 10-12 cells instead of 14)
- Set props higher
- Fix motor coupler vibration (if can't, then change the motors)
- Shorten and double up on the wires.
- Install extra capacitors on power input wires close to controllers.

[AntronX]

AntronX,
wy did you opt for 2 motors?
I have an 1/8 scale that runs on 1 NEU powerplant and
at fun speeds... was it cost? Cause by now you probably are
getting close to the cost of one HV ESC and a NEU motor.
There are really fast boats that run on 1527 and even on 1521
motors on 37v.
That is a very good looking hydro, once you get it
going it'll look very "purdy".

I got two motors because i thought that one is not enough power for the hydro of this size. Guys at my club run these hydros with gas engines that they claim are doing 4 - 6 horse power. To keep up, i figured i would need two of these cheap motors. My main goal was a cheap electric setup that can keep up with gas boats and still cost the same to make. Looks like that is not easy or possible with controllers i tried. I have a feeling that both of these motors may not be enough as well, because they may run too hot if i try to keep up with gassers in a 6 lap race. I was trying to keep this build under $1000 without batteries. I ended up spending $1300 for all the parts. That's very comparable or even less than gas boat of same size. Both motors and controllers cost me $330 total shipped from China. The batteries are from my electric miss vegas. I can use them in both boats. The amount i spent on some tools for this build is not included.

Thanks for the "purdy" part. Its not the purdiest hull out there, but it was available at the local hobby shop for $314 plus tax brand new.

[Ub Hauled]

ANother thing I can tell you, is that those props will not pass the testing period.... that much power is going to chew them up and spit them out.

[Bill-SOCAL]

I applaud your efforts at doing a large FE boat on the cheap, but I also think you are going to find that it is not an easy task. I guess you are already realizing that.

There is a reason most people that run big boats use the big Lehner/Neu motors and Schulze controllers, they work and continue to prove that they work. And even at that they can take a beating in a big boat.

The Castle 240HV was promising, but it is showing a nasty propensity for spontaneous combustion. Too many of them have been reported to have simply gone up in flames while sitting idle for my taste.

Good luck with the project however. Jay gave some good advice and it will go a long ways towards helping you sort this out.

One note, the coupler vibration that you have is very likely the coupler itself. Different makes have been known to be eccentric at best and at high RPM can really vibrate.

[AntronX]

ANother thing I can tell you, is that those props will not pass the testing period.... that much power is going to chew them up and spit them out.

I got Octura X447 left and right. I bought two of these carbon props just for testing, so if they get chewed up, i will just prepare two Octura ones. I am seeing that there is not much choice in opposite rotation props. Does anyone know where i can get more different sizes than 45, 47 and 57 mm props that Octura has?

[AntronX]

I applaud your efforts at doing a large FE boat on the cheap, but I also think you are going to find that it is not an easy task. I guess you are already realizing that.

Thank you, I appreciate the attention my build is getting from experienced FE guys like yourself. Looks like i am realizing that it's tough to get both fast and cheap in the same boat, but there were couple mistakes on my part that could have taken those controllers out. Any controller should be able to handle peak currents higher than it's rated for, but i guess the manufacturer of those cheap controllers was using most cheapest components possible that can survive in a plane. As we all know, boats can be very power demanding, with high peak currents probably due to water not being as easily compressible as air.

The Castle 240HV was promising, but it is showing a nasty propensity for spontaneous combustion. Too many of them have been reported to have simply gone up in flames while sitting idle for my taste.

I have seen people posting about burning hydras, but there were never any data loggers used as far as i could tell, and setups seemed too hot. Couple things I like about Castle is that they got real customer support and they overengineer their boat controllers. There one thing i don't like about Hydras, but nothing can be perfect at the price they offer them. Next choice is Shulze, but sinking dollar value been putting those farther away from my pocket's reach. I am going to take it easy on hydras and will mount them away from everything else for testing, to make sure they don't torch my boat.

One note, the coupler vibration that you have is very likely the coupler itself. Different makes have been known to be eccentric at best and at high RPM can really vibrate.

That could be true, i will test them on my Neu 1515 that has 5mm shaft. The grind down job i did on KB45 shafts was not perfect, and there is some little play between the shaft and the coupler. Its very hard to get them perfect, so i would suggest people not attempt what i did.

[AntronX]

Update:

Got new controllers in (Hydra 120 HV) and ran the boat on Saturday. It did about 45 - 50mph. Amps were 120 peak and 100 average (50 per motor/ESC). This time i shortened wires to less than half what it was before. I also doubled battery wires, ran two wires per connector. I shortened wires on motor's side as well. Surprisingly, voltage drop stayed about the same, about 8 volts at full power. I raised the struts about 3/8". I also tried to align motor couplers and got them centered better than before. I used green locktite to hold them in place. As a result, there was a lot less shaft vibration. I got a little carried away and started making sharper and sharper turns until the servo got ripped away from the boat. I used 6 minute epoxy to hold the servo mount, and should have used proper 30 minute stuff.

Next day i ran it again with struts lowered about 1/16". It ran not as good as day before. I did about half a lap and brought it back. One of the controllers was warmer than another. That controller was also hissing. As soon as i disconnected power, hissing stopped. There was that very familiar smell coming from that controller, but no noticeable burns outside. I did not power it again so far. It was the same motor that had it's controller burn first time. Which makes me suspect that there is something not right with that motor. Hydra 120 should not have been taken out by lowering the prop 1/16" on the motor that draws 50A continuous day before.

I am scrapping this "cheap" big hydro idea. I got enough of burning controllers. I am going to scrap the whole dual drive setup as well. I am taking Bill's advice to go with what's proven, one big Neu and Schulze. Looks like 40-160 has reverse too. Plus the FETs on that thing are gigantic compared to Hydra HV FETs. Hopefully that setup will work. If not, then I am stickin big ol' Zenoah in there, LOL

[Ub Hauled]

Antron, here is another proven option for you to sleep on:

http://www.yge.de/artikel.php?search=yge155navy

[Ub Hauled]

And here a couple of motor options...

Lehner 3060 or 3080 all the way on the bottom (call to ensure availability):
http://www.finedesignrc.com/motorslehner.asp

Neu 22xx series:
http://www.offshoreelectrics.com/products.php?cat=42

[AntronX]

Question

Hi all, been a while since i posted an update.
I have a question regarding prop positioning. Since I already have mounted the rudder along with the servo in the middle for the dual drive setup, I don't feel like ripping it off and mounting it on the side to make room for single strut. Can i mount the prop behind the rudder in the middle, like they do for scale boats? Will there be any problems with this arrangement? I understand that i will not be able to have same flexibility as with mounting the strut behind the boat. Plus, i will have to worry about sealing the hole around the strut, but scale guys do it somehow. I believe the benefit will be much more responsive steering since the rudder is directly in the middle of the prop trust cone. I would like to hear some input from you guys, thanks.

[eboat]

When you have it in line like that will you still be able to get the flex shaft out very well to grease it ??

[AntronX]

When you have it in line like that will you still be able to get the flex shaft out very well to grease it ??

Ha! You got me, i did not think of that. I would have to take the rudder off after every day of running. That would get old with me real fast. I checked if i could mount the prop further under the boat to extend the length of the stub shaft before hitting the rudder, but that nice rooster tail i am also after will be gone.