NQD Cat--Outboard conversion
 

I have a cat hull on the way that I am planning on retrofitting with twin outboards. I want to have the motors counter-rotating...I am new to electric power and am wondering if electric motors are able to be reversed? I am aware that I will have to find a reverse prop as well. Are reverse props readily available?

I have seen these here on the forum and ebay but I am skeptical of their durability and performance...
http://image.rcuniverse.com/forum/up...54/Oi14900.jpg

I am thinking about using either the Aquacraft EP1 or the Graupner GTX 650.

Also, if anyone has any suggestions as to the best place to mount the outboards...ie-center of the sponsons, inside edge of the sponsons, center of the tunnel, etc.

On a side question, does a failsafe work on electrics or does the esc cut off if signal is lost?
Thanks!

RE: 31" Cat w/ twin outboards
 

RE: 31" Cat w/ twin outboards
 

Looking at offshore scale boats with the Merc S-6's, I would have to say the middle would be better. I know motors can be reversed, I have done it with my NQD boat when i put bigger motors in, I swiched the props. I dont know about hobby grade ESC's, But i'm sure you can. You can buy only 3 Octura reversed props from www.offshoreelectrics.com but i rember seeing on www.mhzusa.com they have lots of carbon fiber props, which do not need to be balanced, sharpened. The only thing is, I don't know if those outboard units have 4mm shafts or 3/16ths.
Hope this helped
Dan

RE: 31" Cat w/ twin outboards
 

Yea, this is a NQD Cat. I hadn't read any of the posts here about the NQD boats till after I had purchased it. I'll run the stock setup until I get all the parts for the outboard conversion and do all the necessary "beefing up" of the hull.

So to reverse the motor, you simply switch the wires to the motor? neg to pos and pos to neg? Like I said, I have never toyed with the electrics...only nitro.

RE: NQD Cat--Outboard conversion
 

That's right, you can reverse an electric motor by simply switching the wires.

The Aquacraft EP1 outboard has a 3mm shaft. A 1/8" Octura will fit the propshaft although the fit isn't absolutely perfect (propshaft is slightly small).

Some ESC's shut down the motor if the radio signal is lost. It depends on your ESC.

RE: NQD Cat--Outboard conversion
 

Greg. remember about motor timing.
most motors that go forward ( brushed ) have motor timing . so if you reverse it it will not go as fast

RE: NQD Cat--Outboard conversion
 

So, with the timing in mind, what does Traxxas do in the villain to get the counter-rotating motors?

RE: NQD Cat--Outboard conversion
 

the EP1 uses a sub surface dirve, correct?

and becuase sub surfce drives do not have prop walk, they do not need to have one reversed to counteract a force that isnt there...

although im probably wrong, just giving out soe ideas

RE: NQD Cat--Outboard conversion
 

Correct, the EP1 is sub-surface drive so prop walk shouldn't be an issue. There's also the torque factor from the prop on the water which tends to make the boat list to one side so in theory counter rotating props would cancel this effect although I'm not sure how significant it is for model boats.

Taylor, that's true about the timing. I wasn't thinking about that. It would be fine if the motor has neutral timing.

RE: NQD Cat--Outboard conversion
 

Is the timing info of electric motors included in their specs? I've read on here that the timing of motors can be adjusted in the case that the motor will be reversed....is this true with all motors? Or is this another "it depends" issue?

Since these outboards are going to be put on a cat, I plan on mounting them so that the prop shaft is right at or just below the bottom of the sponsons....so, depending on how well they push the boat, they could end up being surface piercing.

RE: NQD Cat--Outboard conversion
 

yeah they just reverse the polarity, I dont think they mess with the timing on the villain. It originally used a gear to reverse the rotation but they must have decided to reverse the polarity, instead of using a complicated and unreliable transmission. I think it was a good move, the friction from the extra gear probably equals the loss in power of the polarity switch.

RE: NQD Cat--Outboard conversion
 

you cant run a surface pierceing setup wth a sub surface prop...youll have to run the EP1 sub surface, or dint run it at all...someone has already tried to run teh EP1 like that and it didnt work too well....

RE: NQD Cat--Outboard conversion
 

saleen, what was it about that setup that didnt work well....is there a thread on here that details it?

RE: NQD Cat--Outboard conversion
 

Alright well, I've started my NQD rebuild. After stripping all the stock hardware, motors and electronics, I sealed all the screw holes in the hull. Then removed all the decals....man, they must have used some kind of super adhesive for them...a regiment of Goo Gone, denatured alcohol and elbow grease is slowly getting rid of the residue. Next I cut away a section of the stern/upper transom which was in the way of mounting the motors. Then glassed the inside of the transom for reinforcement and to fill the gap created by the cut. Next, I made and mounted a carbon fiber through-hull water pickup for the ESC cooling. Lastly for the weekend, I bench tested the motors. Coincidently, the stock props on the NQD fit on the EP1's. They appear to have a little less pitch but are 4mm larger than the stock EP1 props...we'll try out the NQD props when the boat hits the water.

Also, here is a video of the NDQ running all stock. Fairly fun out of the box, but that vector steering with a fixed rudder leaves much to be desired. [link=http://s159.photobucket.com/albums/t144/fun4ej/NQD%20Rebuild/?action=view&current=StockNQD.flv]NQD Stock maiden voyage[/link]

RE: NQD Cat--Outboard conversion
 

Thats cool i need to do somthing with my NQD boat. I love the carbon fiber pik ups how did u make them???
Dan

RE: NQD Cat--Outboard conversion
 

Thanks man!...we'll see how well it works next weekend...hopefully.
I modeled it from the MHZ pickups.

One of my LHS sold me a small sheet of the carbon fiber. I epoxied 2 thicknesses together, evened up the sides with the dremel. I used the dremel to start the notches then used a file to even them up and take them to the thickness of the hull. Used the dremel to drill the hole as well.

RE: NQD Cat--Outboard conversion
 

Don't forget to reverse one of the motors by switching the wires and use an opposite turning prop with that motor.

RE: NQD Cat--Outboard conversion
 

I was planning on doing that but offshore electrics told me that the stock motors have advanced timing...which reversing one motor would result in one not turning at max capacity....to my understanding.

So, I'll see how it performs with the non-counter rotation first...then venture into counter-rotation if need be. I was also told that going brushless would be the best option for counter-rotating the motors....but I need to get the basics of electrics down first....again, this is my first venture into electric RC

RE: NQD Cat--Outboard conversion
 

you can run non counter rotation fine, turns both ways equally well, we have on our coastguard boat(real boat)i used to crew on, twin 250 Merc's i trim the left one about 2 degrees down, and the right one two or so degrees up - rides flat and true, you will likely have to experiment with the trim.. the motors look like 05's ?? if they have the same bolt pattern you could just replace them with adjustable timing 05's or if you want to do a bit of diy, removing the endbell and rotating it, screwing back together through the side of the can will get you where you need to go, personally id get two mod 05 cans and throw super stock armatures in them, reverese the timing on one... some actually have same amount of timing in each direction

RE: NQD Cat--Outboard conversion
 

RC boats don't always handle the way real boats do because the power we have in rc boats is way bigger in scale than what you would normally put on a real boat. Why do you think that most all rc boats that have twin motors like the villain, have opposite turning props? As far as adjusting the timing on a sealed end bell there is a tutorial on here somewhere about the johnson motors which would be the same for your motors. Its not that hard to do.

RE: NQD Cat--Outboard conversion
 

wheelnut, is this the tutorial you are referring to?

[link]http://webpages.charter.net/torquer/index/63706.htm[/link]

So, what is "timing" in electric motors?

In this tutorial, the motor started at 15 deg. He then timed it to 0 deg. If I were to do this modification, wouldn't I want to turn the timing back to -15 deg. to run in opposite sync with the untouched motor? (or put both motors at 0 deg. timing?) Also, by the pictures in the tutorial, is it safe to assume that 0 deg. timing is denoted by the motor mount holes on all electric motors?

RE: NQD Cat--Outboard conversion
 

i have a question wear can i get one of the NQD boats at or there main web site?

RE: NQD Cat--Outboard conversion
 

That is the tutorial, but if I am not mistaken you would want to run both motors in 0deg timing. Yes that is correct about the motor mount holes being the reference point for 0deg. Some motors have markings on them denoting the degrees of timing.

RE: NQD Cat--Outboard conversion
 

I got mine on ebay

RE: NQD Cat--Outboard conversion
 

I have another question. Why do you want one ?