Im asking the impossible

[tim slocum]

I have a co worker who heard Im into boats, so he wants me to help him with a boat he's been working on for 20years.Actually, he stopped years ago, because he didnt know what kind of powertrain he needed.Im trying to understand from him what boat he's got. Alls he knows is that its about 30inches long,10inch wide, v bottom racing type boat made by Dumas. Its all wood construction.He said that the area for the motor is about 8-10" x 6-8". He said the cockpit area is removeable.The only hardware he has is a piece that mounts to the stern with the rudder attached to it. He has a flex cable also. He wants me to recommend a motor,ecs, prop,batteries and he wants it to be FAST. So far for a 30" boat I was thinking Speed 700,Jetti esc, and a pair of 7.2v 4200mah wired for 14.4v. I need to know what size prop to use with this motor/batteries? Any info would be great. :)

[Rex R]

well presuming that it is a 3/16" stub shaft(prop) I'd start with some graupner CF props k-series 40-45mm. they are fairly cheap(iirc about $7) and don't need balancing. offshoreelectrics should be able to supply most of the hardware as well as the props(he'll need an octura hexflex motor coupler 5mm to whatever size dia shaft prolly .13") hth
rex

[tim slocum]

Rex, the short propshaft is 3/16th's.I've been looking on Offshoreelectics for the hardware. I dont know yet what dia. the flex cable is.Thanks for the prop size/type/brand recommondation.Whats the CF and K series mean?

[CG Bob]

From the rough description, it sounds like a Dumas Deep Vee 21 (http://www.dumasestore.com/catalog/product_info.php?cPath=47_58&products_id=429).

The BL motor, ESC, and prop (http://www.aquacraftmodels.com/accessories/propellers.html) (AQUB9715 prop, 40x53 mm) combo for the AquaCraft Super Vee 27 (http://www.aquacraftmodels.com/boats/aqub17-main.html) might be a good unit to start with.

[Rex R]

Carbon Fiber. not sure what Graupner had in mind about the 'k' series...they are marked with a 'k'prefix ex K45 (nice replacement for the super vee btw :)). if it were my boat I'd spring the extra $15 and get steven to install the motor caps, diode, and the brush coolers :). popular sizes in flex shafts are .13"(for a 700 motor this size will work), .15"(for the super vee motor get .15"), and .187". IF the boat was set up for an internal combustion motor, you may need to get a different shaft(iirc some of the gas/nitro shafts used a square cable end)
edit
assuming that it is the deep vee21 with flex shaft #2355 then the shaft is .15" only Q is what sort of end is on it(motor end). so you'ld be set for either a 700 motor of the super vee power pkg(would need a motor mount in either case).

[pompebled]

Hi Tim,

I've got a 25 x 10" boat and a 700 motor looks tiny in such a large hull.

As 'your' boat is even bigger and the owner wants to go fast, you might even consider an 800 motor on 20-24 cells.

The heavier boat will run smoother than on 'only' 12 cells and a 700 motor.

Just a thought...

Regards, Jan.

[Shaun Hendricks]

I'm with CG Bob on that SV-27 suggestion. Get a pre-made kit and all the excuses for finishing it disappear, plus it's modern components.

Brushless will make that thing rip, even being wood. He might want to reinforce the motor mount area though.

[gpzy]

About half way down this page there seems to be a pretty nice combo esc and motor that will work.

http://www.offshoreelectrics.com/products.php?cat=42

Product ID: dh-blcomboaq
AquaCraft Motor & Esc Power Package

Details
This brushless combo system will push out
close to 3/4 Horse Power! Its a drop in
unit that includes all the batteries and
motor connectors! No soldering required.

[tim slocum]

Guys I printed a picture of a Dumas Super V21 and showed it to my coworker today. He said,"Thats it!" I showed him the hardware package that Dumas makes for it and he said he has that also.I told him about the carbon fiber props and he liked that. I mentioned that he could get a complete RTR SuperVee27 for around $300 or just use the SV27 powertrain for about $170.He said he wanted to finish the boat he has,so the RTR option is out.So, his choices are the Speed 700-800,SV27drivetrain, or he's still thinking of possibly using a small weedeater motor.The balls in his court now. I give him all the info I can and he makes the call. Its his money.We'll see what happens.Thanks for the info guys

[Rex R]

tim: one last bit of info(for now), the 'DR' motor mount can accomedate either a 500 series motor(the SV motor fits this catagory) or a 700 series motor(not at the same time, natch). hope we get to hear more about this project :).
rex