What motor should I use?

[rcboatlover]

I got a old Dumas 60 deep V hull for a really good deal and want to make it into a retreval boat to bring back dead boats. The boat is around 40" long and really deep, and I need to know how big of a motor I would need to push it. I plan to add a system to the back that can hook a stalled boat and pull it back to shore.

Can any one suggest a motor, ESC, and prop for this project? I know it will be just a guess, but your advice would be a great start. I mostly work with gas boats. I want to keep the cost as low as possible since it's just a tool, not a toy.

I want to use a gell cell for powering it and reach at least 20mph. The motor will be water cooled and have pleanty of air flow around it.

Thanks for the help!

Dale P.

P.S. How about this for a motor?

E-Bay auction

 

[cat]

Hi although i don't kwon much about this i'll try to help you.

For the motors you should use somethin with loads of torque such as Graupner or Robbe 700 or 800 size, try to use to motors. Take a look at some real tug boat so you get a general ideia. To deliver the power to these motors use a high quality speedo or switch. As for bateries use a lead acid bateries, since these are 12V and available at a variety ocf capacities (2Ah or 2000mah should last for a weekend)

PS dont forget that these motors draw a good amount of amp's and they are torq based motors.

 

[Pennywizz6]

Dale,

That motor is way over priced, buy it now for like 4$ on robotmarketplace.com There are faster and more powerful motors out there, that thing is an amp hog and you will get very low run time. The johnson motor is a better choice, or if you can spend around 40$ get a powerful DeWalt drill motor. Fast and extremally powerful.

Phil B)

 

[J Solinger]

I would recomend a Gaupner 700 on a gear drive, an ESC like the Ziya or SC8 from Offshore Electrics. For a prop I think if you go with a X440-X445 you will get the grunt you need. Wide open running won't be an issue, however, when you hook up to another boat to pull it in the speed control will heat up. Thats why I recomend the gear drive.

The other day I was at the LHS and saw a rc boat that was designed for shore fishing. You use the boat to drive your line and bobber out to deep water and drop it. I was thinking of using it to bring a tennis ball and line out to the stalled boat. When the line is over the stalled boat you drop it and reel in the dead boat.

 

[TXTRCR]

You may also try the 12volt motor, MSC, and Sealed battery available from www.dumasproducts.com . I have the same plans for a hull i just picked up.

I would also recomend that you get a sub surface drive setup and install the rudder under the hull like a tug style set up. that way you can back up to a stalled boat and not push it away with a rudder and drive hanging off the back of the boat. most of my boats have a prop behind the rudder which could do some damage to a stalled boat.

http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXE528&P=7

speed control

http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXE553&P=7

motor

http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXE559&P=7

power

I saw some one saying to use the standard 7.2 volt stick packs because they had 2000 MAH if youll look at these batteries they are 2.5AH and 5AH. whole amp hours not milli amp hours. more power for your motors.

Im not sure if you could get up to 20 on this setup but you dont need speed anyway. you need pull and lots of it. large diameter low pitch prop is best for grunt. dumas makes a tug boat that can pull a cannoe with two grown men in it, you may want to check out there site and get the hard ware and electronics they use in that kit.

 

[rcboatlover]

Hey thanks for the replys!

I was thinking of the project today and agree that the motor should be geared down. Instead of gears I would rather see a belt drive though. Gears rob alot of power and can be noisy. I'll have to check out sources for notched pullys and belts. What ratio should I try first? 2 : 1 ?

As for the motor I agree that the one in the auction isn't the best choice. Just something I saw the other day. It is made by Johnson and is larger than the 700, but I does seem to draw alot of amps. I will have to check out the robotmarketplace.com site. $4.00 for a motor is exactaly what I wanted to spend!

Thanks for the links to the Dumas web site, but I don't think I will ever buy from them again. Way to dated and over priced! There running hardware is a complete joke and should be against the law to sell at the prices they are asking.

I saw the picts of the tug boat you are talking about and it would make for a great retreval boat though. 20mph... Your right, I think I will lower my expectations to around 15mph.

Well thanks again, I will look into a 700 to 800 sized motor and gear drive for the project. I might even use two... Just have to see.

Keep the ideas comming!

Dale P.

 

[Andrewg]

The simplest setup will be direct drive

the motor neds alow kv 500rpm/v or less and lots of torgue

these motors consume very little power

submerged drive willg ive better thrust and low speed control

a prop of 60-80mm diam will use the tqrque fothe motor and give good thrust

a steeerable outdrive will give the best manouvrability

automotive fan motors using 12-18 volts or a motor like a graupner 900 willl push 50 lbs - the boat doesnt have to be fast 5-8 mph will be adeuate but manouvrability is paramount a bow thruster will help

A deep vee mono will lack stability compared to say a cat and reversing will not be as effective as it could be unless you can get the prop wash flowing deeper than the keel.

 

[DH Racing]

I think yopu are putting way to much into a rescue boat. First gear drive is very good in fact little to no loss of power and 48 to 64 pitch does not make a lot of noise. The old ones at 32 pitch would break a ear drum. Graupner makes a 920 torgue that would be fine dorect. I know I use one now in my rescue boat. The Johnson 970 (EBAY) is another great motor to use and CHEAP!. It will run well at just 6 volts with a 48 to 51. Slow big props work best to push a load. Just use a simple gell cell battery, cheap and runs for ever. I run two 6 volt gells in paralell at 7.5 amp hours each. The torgue is much better at 6 volts than at 12 and the amp draw is on average 7 to 8 amps pushing a gas 1/8th hydro! You know what a tank those boats are dead in the water!!!! I have never used the boat for my own electric boats but gas and nitro guys everytime I go out.

Keep it simple and you will enjoy it more. Mine has worked great for three years now on the same bateries and motor.

David

DH Racing

Hey thanks for the replys!
  I was thinking of the project today and agree that the motor should be geared down.  Instead of gears I would rather see a belt drive though.  Gears rob alot of power and can be noisy.  I'll have to check out sources for notched pullys and belts.  What ratio should I try first?  2 : 1 ?

  As for the motor I agree that the one in the auction isn't the best choice.  Just something I saw the other day.  It is made by Johnson and is larger than the 700, but I does seem to draw alot of amps.  I will have to check out the robotmarketplace.com site.  $4.00 for a motor is exactaly what I wanted to spend! 

  Thanks for the links to the Dumas web site, but I don't think I will ever buy from them again.  Way to dated and over priced!  There running hardware is a complete joke and should be against the law to sell at the prices they are asking. 

  I saw the picts of the tug boat you are talking about and it would make for a great retreval boat though.  20mph...  Your right, I think I will lower my expectations to around 15mph. 

Well thanks again, I will look into a 700 to 800 sized motor and gear drive for the project.  I might even use two...  Just have to see. 

Keep the ideas comming!

Dale P.

69255[/snapback]

​