Looking To Go Brushless!!!

[Tuslow1]

I want to do some brushless projects but looking at the brushless motor charts is soooooooooooo confusing... If you look at the charts (a novice like myself) you see RPM per volt and want to order up the smallest motor on the chart... simply because it looks like you could run a 540-S6 wind with a 7.2 volt pack and your boat will run about 3,000 MPH with the right prop.. and that might be true if you boat was no bigger and weighed no more than a paperclip... But the truth is we dont boats of that nature... Whats even more confusing is that the motor charts tell you how many cells it can handle but not how much weight or boat surface that motor will safely push.. That all takes you back to square 1, what motor do you get????
So I'm asking all of our senior brushless boaters and whomever else that knows, because I don't, what motor do I get????
The hulls I want are all 3 ToysPort hulls offered from Offshore and all of them will run on 14 cells max, I only intend to buy about 10-7 cell packs.. not going to do different cell counts for different boats... HELP???

[BoatDoc]

for the syncron (one of the toysport hulls) try 12 cells and a hacker 10xl, or a motor or similar rpm. with 3700mah or higher cells, and a 99amp or higher esc, you'll get a nice solid 4 minute runtime (good P-offshore setup).

you could also do this: take 25,000rpm, divide that by the number of cells you are using, and that will get you into the ball park for the rpm/v rating of the motor. for 6 cells, lot's of guys use the "s" motors, for 8-10 cells the "L" motors aren't a bad choice, and for above 10 i'd say go with an "XL". that should get you a decent "sport" running boat. for racing, a higher rpm motor would be better.

if you're budget minded, look at the nemisi/feigao motors. they are decent runners, and only a fraction of the cost of hackers/neu's/lehners. personally, i have 4 nemi's, 1 hacker, and 2 lehners.

like i said...for sprint racing, you'll want a higher rpm. for example, i run a 4,440 rpm/v (nemesis 8s) motor in my N2mono...that's about 31,000 "free" rpm. the boat is competitive, but there are many out there that are faster. racing also means (usually) higher ratings on the esc. i know of several n-riggers that run at about 115amps. in contrast...my n-rigger runs at about 70, so i get by with my 99amp BK controller.

once you get through a couple of builds, it will be easier to sort through all the stuff, and you have lots of great resources here on the 'net to help you out. my .02.

[Tuslow1]

Thanks Doc,
you just gave me one key to choosing a motor, the other side of the coin is that this is a multiple sided lock.. what formula could I use to get the right wind of motor to push the weight of a particular hull??? Then I need the general amperage of the cell sticks to get a correct speed control.. Remember, I will be running a slightly larger and heavier hull than my son (SV27) and I need to stay ahead of him with class. I never thought that the sorry little red boat that couldn't get out of its own way would end up being the fastest boat in the pond... I do have bigger and faster Gas boats that will run off and leave the little red boat, but I dare not put them in the pond (WAYYY TO LOUD!!!!) The kid taunts me now, come on Dad race me with the BlackJack again?

[BoatDoc]

with the amount of power that's available today...i'd say go with no less than a 125amp speedo. the castle 125 is an excellent piece of gear. however, if you get one, i'd strongly suggest you get the castle link along with it (an extra $25) and put the new software into it. there were problems with the old software on the controllers, and it caused LOTS of problems. i've run one after the upgrade and it worked flawlessly.

[Tuslow1]

next question, how do you get your amp rating? what is the formula for figuring that out??? someone told me it is not from your cells but has to do with your mAh rating???

[BoatDoc]

figuring out the amps can be tricky. these days, in many cases, it's just easier to look at what others have done and had success with. there's a program called "FE calc" that can get you into the ballpark. the 12cell/hacker 10XL setup i listed above is a set up that i know works. i know it works because others besides myself have run it, and i've run it too. they did the science for me! i can't afford too much experimentation, because if i smoke a motor or esc, i can't afford to replace it.

[PatrickJ]

Power to weight ratio is important hear. You need to weigh your boat then work out how heavy it will be when everything is in place. To crush your son you need a much better power to weight ratio than him. In choosing a good brushless motor yor need a motor that can put out big watts at 25000 to 30000 rpm with out load. I read that 110 to 125 watts per pound is good for oval racing and 200 watts per pound is good for saw. To get these power to weight ratio multipy the power to weight ratio by the total ready to run weight of your boat. Now you should now how much power ( watts ) you need. I is important that you get a motor that is large enough to handle this kind of power. If you go on lehner's web site you can get the specs on some of they motors. Torque is very important in wet running, heavy hulls so it important to get a motor that has alot of torque and revs in the 25000 to 30000 range. Torque determines what size prop you can turn.

[SouthJersey-FE]

Gear reduction is a way around motors with less torque and more rpm is it not? Maybe a way to save money....Just takin a shot in the dark here.

[BoatDoc]

there are lots of guys that run them in offshore setups as a way to decrease amp draw and increase run time. you'll have to fiddle with different gear ratio's but it can be a good thing.

[Tuslow1]

Thanks a million,
Doc I've been playing with that FE Calc ever since you told me about it, thats pretty cool but I think the motor sizes are not high enough. Never the less It really gets the idea across, is there a higher one available???? Gears are yet another way, but I want it on Direct Drive and too big of a motor requires too many cells to power it... I only want to run 14 cells max...

[Tuslow1]

I've seen a BlackJack26 with a SV27 motor in it.... anybody know about that???

[SouthJersey-FE]

I've seen a BlackJack26 with a SV27 motor in it.... anybody know about that???

That would be Steven V's Black Jack. I plan on building one of them down the road. Steve sells the SV motor & esc package @ OffShore for a little over 150 bux. Great deal!!! I bought one for my 26 Scat Cat. He is still workin on the project. I am waiting on updates myself.

[BoatDoc]

tuslow-there are ways to change the available motors in FeCalc. at the moment, however, i can't remember how to add them. i'll look into it and get back to ya.

i've heard some talk about using the SV27 power package for other boats. it looks like a cool idea for sport and fun running. it's a good way to get some speed on a budget. most speed controllers cost as much (and usually much more) as that whole package! i know of a few guys that thought it would be cool to run "spec" hydro class based on the SV27 motor/esc. don't know if i'd do it myself, but i know that it would be cool for someone just getting into the hobby. i, for one, would like to see how some of these boats turn out.

[Tuslow1]

Soon as I get some word or another, I'll be building one!!