Best Electronic Speed Controller for Class 7 BB

Hey all,
I'm getting to that point in my build where I'm looking at ESCs for my Iowa-class, specifically the Viper Marine 40 that Strike Models sells. Firstly, the boat will be a 6-volt setup, eventually containing three 6v 12ah SLAs powering two 550 motors along with all the rest for an eventual full-combat fast-gun rig. Secondly, will the Viper Marine 40 do the job, or would a more potent speed controller be better for what I'm doing? Mind you, I'm not looking for the best and brightest, I'm just looking for what will do the job to let me get the monster on the water and putter around looking pretty. My radio will be a Futaba FASST 6-channel if that affects anything.

 

I should have mentioned that because of my driveshaft setup, I'm not able to gear down my 550s, but will be direct-driving them.

 

The original intent was to gear down the shafts, but when I consulted with some folks on the situation, my main driveshafts--which were done for me by my hull's original owner--wouldn't accept a gear-driven setup because the diameter of the shafts themselves was the wrong size. The skegs were already built, and I didn't want to cut them off and rebuild from scratch; opinions from folks with a lot more experience than me said to keep the current shafts and direct-drive.

 

Probably 3/16 shafts, a very comon size in the scale ship arena.

Not a show stopper though. A dogbone or universal setup would let you connect the shafts to gearboxes without having to rip out the shafts.

 

My drive shafts are actually 1/8 inch. Now, if I stayed with the mayhem of direct drive on a class 7 battleship, how much harder are the motors working? What sort of motors should I look at to account for the extra work they'll be doing?

 

We had a guy show up with an Iowa a few years ago with direct drive 550s and he didnt last long. It melted the wiring ! Mikey deskin helped put 700s in it over night. Worked fine next day. If you use the battlers connection gear bos on the motors and then a dog bone to your shaft and use like a 1.5 to 1 ratio you might make it.
Buddy

 

I'd recommend around a 2.5 to 1 ratio in the gearbox with standard 550 type motors on 6 volts. Two motor gearbox setups pushed the Richelieu around pretty well though lacked enough torque for tight turning in the very competitive fast gun battling.

If you are not concerned with hitting fast gun speeds and plan on going with a scale'ish slower speed, the gearbox route is definitely the way to go.

 

Lots of good info here, thanks guys. As for speed, yes, I do plan on battling at fast gun speeds sometime in 2012, but this year I'm solely concerned with getting the monster on the water and laying the groundwork for a conversion to combat readiness. Having looked at Stokamoto's Missouri build thread, I see he's got two gearboxes dogboned from his motors to his shafts, and that route seems like it'll be the best way to go about it, though I do hope that the eventual speeds will be at the fast gun rate.

As for that one fellow melting his wiring with directly-driven 550s, what was his setup to cause wires to melt? Were the motors pulling that much juice or was his speed controller improperly set...? My short-term goal is to get on the water by July to putter around, but I'd rather not put to sea and then end up sunk because of an onboard fire.

 

Makes good sense; here I was thinking it was something else.

 

All my twin 550's are running direct drive. I have a Arizona@28lbs and a sodak @36lbs. I have them dogboned and running direct with no esc. Use heavier wire (of course) and bring it down to speed with the drag discs.
No fires and no problems.

 

Data points indeed. Especially since his heaviest ship will be at least eight to ten pounds lighter than mine, heh, but nevertheless, that is good to know; thanks Iceman

When it comes to my ship, I'll be running 1.5-inch 35-pitch 4-blade screws, made by the good folks at Strike Models. I could have gone bigger, but I wanted to make sure I had room between the blades and the bottom of my hull; the skegs looked a touch close, so I gave myself breathing room. I will be running an ESC, though, just because I don't see myself being able to run without one (I didn't get the kit to do the MAG servo throttle setup deliberately).

 

ok answers...
6 volt system, two 12 amphr bricks in parallel
1 3/4 prop, 35 pitch
acceleration and turning rocks
My three friends with iowas have all run twin 55o's direct with no problems either
lasts about 45 minutes constant battling