ESC for twin motor boat

[stduck54]

I am setting up a scale model (25 inch long) of a tugboat as a RC model. It has twin electric motors, running off a 7.2 v pack. The motors have no markings but they are approx 38 mm circumference and pack a bit of a punch. I am using a Spektron DX 6i. (which is really for aircraft but has elevon mixing which is useful for controlling twin motors). To set the tug up for tight turns, the motors need to be able to run in opposite directions. I now understand it needs separate ESC's. What's more, these ESC's need to be able to handle forward, stop and backwards positions, which the cheap ESC's a local shop offered me, do not seem to do. What brands/types should I look at and who supplies them. (mail order, I live in Asia). Any idea of price? I have seen some at USD49 each on the harbor Boats site, which seems expensive and I do not know if they are the right ones? Also, the boat has a firefighting pump. At a local shop they told me I needed an ESC for that. I have one, no brand. Do I really need an ESC to control a pump that only needs on and off? I would think that a simple relay plugged into the receiver (maybe in the landing gear slot) would be sufficient? Does such a thing exist?

Then there is the question of how exactly to set up the DX6-i, but I will leave that until I have the correct ESC's installed.

[pkboo]

Hi Duck welcome! First of all a word of caution and consideration, depending on where you're from using an aircraft "frequency" might be illegal if used in surface applications. Besides that flyboys aren't really happy if you're boat is the consequence of them crashing :eek:

You don't need separate ESC's, it's recommended though for a tugboat cause you'll have extra manueverability. For on/off thingies you have some other stuff that more knowing people will help you with, just stay tuned :D Boo

[mfr02]

For a tug you could easily do worse than ACTion's P94
http://www.action-electronics.co.uk/home.html and scroll down - its a new product.
For the pump, a cheap ESC might well cost less than a switcher, and be more compact than a servo plus swiches.

[jshander]

Hi Duck,
Several members in our Wisconsin Scale Boaters Association like this dual ESC mixer, using a Y connector to connect it to the servo for the rudder channel. Any 2 channel radio even works with it. I even use this to power two geared Astro 25 motors without it ever heating up.
One member took off the metal case of the smallest sabertooth and uses it in a 9" plastic model kit that was converted rc to run two motors without any rudders at all. It is a whole lot cheaper than buying two speed controls.
sabertooth dual esc (http://www.dimensionengineering.com/Sabertooth2X10RC.htm)


The company also sells a conversion for your spectrum that gives it a longer run time off the batteries if you are fairly hand with a solder gun.
3.3 v regulator (http://www.dimensionengineering.com/DE-SW033.htm)

spectrum mod sheet (http://www.dimensionengineering.com/appnotes/spektrum_mod/spektrum_mod.htm)
Jim Shander

[Ghost 2501]

Hi Duck welcome! First of all a word of caution and consideration, depending on where you're from using an aircraft "frequency" might be illegal if used in surface applications. Besides that flyboys aren't really happy if you're boat is the consequence of them crashing :eek:

You don't need separate ESC's, it's recommended though for a tugboat cause you'll have extra manueverability. For on/off thingies you have some other stuff that more knowing people will help you with, just stay tuned :D Boo

PKBOO, stduck said he's using a spektrum dx6i, which last time I looked at the specs was 2.4ghz self-seeking, and so because its more akin to cell phone technology with rx's paired to tx's by means of a code number, (like a telephone number), the tx will only talk to its paired rx, and not one belonging to the guy who happens to be flying his beloved balenca decathlon next to him. because of this they are legal for surface and ground, just cant be used in submarines but that is because of the technology NOT the law.

am setting up a scale model (25 inch long) of a tugboat as a RC model. It has twin electric motors, running off a 7.2 v pack. The motors have no markings but they are approx 38 mm circumference and pack a bit of a punch. I am using a Spektron DX 6i. (which is really for aircraft but has elevon mixing which is useful for controlling twin motors). To set the tug up for tight turns, the motors need to be able to run in opposite directions. I now understand it needs separate ESC's. What's more, these ESC's need to be able to handle forward, stop and backwards positions, which the cheap ESC's a local shop offered me, do not seem to do. What brands/types should I look at and who supplies them. (mail order, I live in Asia). Any idea of price? I have seen some at USD49 each on the harbor Boats site, which seems expensive and I do not know if they are the right ones? Also, the boat has a firefighting pump. At a local shop they told me I needed an ESC for that. I have one, no brand. Do I really need an ESC to control a pump that only needs on and off? I would think that a simple relay plugged into the receiver (maybe in the landing gear slot) would be sufficient? Does such a thing exist?

Then there is the question of how exactly to set up the DX6-i, but I will leave that until I have the correct ESC's installed.

most esc's have two-way functionality, though some have a "brake" feature which allows a burst of free-wheeling before applying reverse, ok for cars and some boats, BUT a pain in the *** for boats. esc options are Mtroniks, Elecronize and Proboat. the Mtroniks and Proboat have a BEC system built in, though i think the electronize ones do not have BEC and so need a seperate battery pack.

most likely you will get away with a proboat tornado 50 (it however only has a 20A reverse and a 50A forwards), a little overkill but they are 100% waterproof and dont need to be set up. the Mtroniks, a Vioer marine 15 or Viper marine 25 will do the job, again these are waterproof.

as for your DX6i, you will find that the elevon mixing is on the RIGHT HAND stick in its default mode, and I think it can be turned into another stick mode to put it on the LEFT HAND stick.

I use a 40mhz Futaba set, however even though its configured for a surface frequency, (35mhz is the uk air frequency), it still says "computerized airplane system",

anyway some wiring diagrams can be found here wiring diagrams (http://www.rcgroups.com/forums/showthread.php?t=783582)

[pkboo]

Ghost, thanx I didn't look it up (I'm so sorry...!) however I do understand the 2.4Ghz, it's just that he mentioned that he was a going to use an aircraft radio.....for a boat :o Boo

[Ghost 2501]

Ghost, thanx I didn't look it up (I'm so sorry...!) however I do understand the 2.4Ghz, it's just that he mentioned that he was a going to use an aircraft radio.....for a boat :o Boo

even my 40mhz futaba says "airplane system" on it, spose its because its the flyers that make more use of the 4 and 6 chan radios

[Umi_Ryuzuki]

Welcome to RCgroups.

$49us Is not a bad price for an ESC.
You don't need an Esc for the pump. A simple switch activated by a servo will
work fine.

Harbor Models
Cornwall Model boats
Horizon Hobbies

All have decent ESC that they can ship around the world.

[Ghost 2501]

and westbourne models

[785boats]

I'm going to order one of these today from R2 hobbies to test it out.
Pretty cheap & close to home. I won't know if it is any good for 10 days or so.
It says 200 amps, not that you (or I) need that much, but the cables or the connectors don't look up to that sort of current. We'll see.
http://www.r2hobbies.com/proddetail.php?prod=rcps81710&cat=43
Cheers.
Paul.

[woodybob]

Here’s another option, FR30HX Controller (http://www.electronize.co.uk/fr30_series.htm)heavy duty 30 amp rated microprocessor controller, about $87.00 delivered (USD). It can handle dual motors. 6 to 24 volt input.

[stduck54]

Thanks guys.

I have found some reversing 50 amp ESC's with BEC here in Singapore, plugged them in and we have a lift off. The servo for the coupled twin rudders were plugged into aileron, left motor into elevator and right motor into tail rudder. I can now use the right stick for steering as well as throttle for line ahead/astern and moving the left stick left or right throws the motors into opposite directions for tight manouvring. The hardest thing was to get the motors to start running at the same time, the mixing had some weird effect on that. I jury-rigged the wiring (thanks Ghost, thanks PKBoo) and the next step is making it permanent (and yes, the pump works fine off the cheap ESC activated by the landing gear switch) One problem left. One probelem left: the motors do not run at full speed when the sticks are on full throttle. Something to do with the mixing and/or the ESC setting? The no-brand ESC's (the shops love repackaging no brand stuff here in Singapore) came with basic instructions, but nothing on re-setting. I have read the Pro-Boat instructions Umi posted, but that did not work. Does anyone have any bright ideas?

[Ghost 2501]

stduck can you post a pic of the said esc's you brought?

if it is the proboat type, (see my pic), then try reversing the wires to the motor on both of them, then adjust the servo reverse settings on BOTH channels. (or swap the props round) which ever works best.

it only gives 20A reverse.

if that dont work, check your EPA's (end point adjust) or turn OFF dual rates. (dual rates cut down servo travel)

[Kmot]

There is a brand new esc on the market that may be of interest:

http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXVDU1&P=Z

[stduck54]

OK, will send a pic as soon as I get back to S'pore.