Motor selection for dumas shelly foss 36"
 

Hello all,
Been reading around and have found much good info. However, I have a question specific to the project I am undertaking and sort of general to motor selection. I am going to build a 36" Dumas Shelly Foss tug and am looking for advice on motors. I would like to not break the bank, yet at the same time get something that works well. I am planning on running dual motors and dual esc's with the Dumas supplied hardware kit which includes a gear reduction. I had been looking at using the proboats esc (http://www.horizonhobby.com/Products...ProdId=PRB2314) as per several recommendations on this forum. I intend to run the boat at 12 v.

That being said, I am looking for recommendations for motors. The Dumas site says to use their 12v or 6v motors but those seem rather expensive. In searching the web I found motor #2 at the loyalhanna site http://loyalhannadockyard.com/ to look pretty good but I'm not sure as there seem to be so many options. Would that motor work? Are there any other recommendations that people can suggest? Just sort of looking for any and all advice as far as motors for my project go.

I would just as soon buy a motor new from a site as opposed to pull them from scrap machinery.

Thanks, if any other info is needed let me know.

Brian

RE: Motor selection for dumas shelly foss 36"
 

Cain If I had one suggestion for you it would be to scrap the idea of using Dumas's gear system. I have seen a number of them over the years and they will give you a problem. Instead I would use a gear box from
http://www.mackproductsrc.com/index.htm
or make your own belt drive sytem from parts from either small parts co. or Spd co. I don't know if you have a lathe or not but one would be adviseable. As far as the motor goes if you check the mack page you will get a very good idea of a motor for this tug. Mack sells top quality goods for Dumas and other kits. I don't have any interest in them except they have always sold me very reliable items. Just My 2 cents hope it was worth reading.

RE: Motor selection for dumas shelly foss 36"
 

Hi,
I agree with Tugguy. Its your money and you can do as you wish but I don't care much for the Dumas reduction sets. Too noisy & fiddly to set up. I have a Shelly Foss and I used 3700 Pittman motors from Harbor Models. I am sure there are other suppliers but thats where I got mine. The advantages are you run them direct drive, they are quiet, unbelieveably powerful (they also are in my Mr. Darby, about 3 times the weight of the Shelly Foss) and they draw super low current so the battery lasts a long time. They also don't overheat.
Anyway, like I said, its your money and you can do as you wish but that would be my suggestion.

Pete

RE: Motor selection for dumas shelly foss 36"
 

I run the two 6 volt $55 Dumas motors in the crockett with each turning 4 blade 2" dia, 2" pitch Dumas props with one $40 pro boat esc and when done the esc is still cold, Dumas has a chart that comes with ther motors it says a 3 blade, 2" dia 2" pitch props (all the props used are Dumas) will pull 2 amps when connected to a 12v Dumas motor and a 3" 3 blade 2" pitch prop whem geared down 3 to 1 will pull 1 amp and produce 4350 rpms at the motor. You can save some money and use only one speed control.
By the way I also uses a single proboat esc with 2 Grapuner 12v 700s turning 1 3/4" 3 blade props direct. their max eff rating is 12.5amps each, the esc did get warm but I ran it hard, I could still hold it al long as I wanted to. Randy

RE: Motor selection for dumas shelly foss 36"
 

So if i wanted to opt out of using the dumas gear train, what sort of RPMs would I be looking at needing? 5000? less?

Given that those 3700 pittman motors appear to be not readily available are there any other suggestions for similar drive units I could use that wouldnt require the gear train?

Thanks for all the advice its much appreciated.

B

RE: Motor selection for dumas shelly foss 36"
 

Check this place too:
http://www.sciplus.com/category.cfm/subsection/18
Dave

RE: Motor selection for dumas shelly foss 36"
 

The biggest prop Dumas shows "running direct" on there chart is there 2" dia, 2" pitch 3 blade. Anything larger without gearing down, Dumas says (current is over the maxium rating for motor) I ran the 4 blade and 3 blade on my crockett 2 motors, 2 props direct and my crockett does about 5 mph, dumas shows 2675 rps at motor with the 3 blade props.

RE: Motor selection for dumas shelly foss 36"
 

twin 700 series i dont know what brand mine is i have the 26 inch with one 700 somthing motor running on 12 volts can pull my 14ft carolina skiff fully loaded with 12 gallons of gas and me id say it weights something like 650-1000 pounds not really sure

http://i121.photobucket.com/albums/o...keboy/tug2.jpg