DJLaPalme

I have an eight foot long PT boat that I want to power with electric motors. I have not decided whether to go with the scale three motor setup or only with two. I believe this size model will end up weighing close to one hundred pounds. My question is what motors would you recomend for this boat and where might I find them? I am planning on running twelve volts and would use reversing ESC's. Any help will be greatly appreciated. Dennis

Alexanderd

Dennis check out the motors from mobile marine models they come in 12 and 23 volt Iv two for my 76 inch Tug

Alex

Hydro Junkie

One option would be geared car window motors. Lots of torque and with an overdrive gear ratio, could be the way to go for 12 VDC

Rich404

Hey DJ,

Wow that is huge.

I would run the boat using (3) Astroflight Cobalt 25's or 40's. I think a 2:1 ratio would be the way to go to keep the amps down.This set up should get the boat up to a nice cruising speed. Be wary of cheap electronics because a 100LB boat won't be kind to them.

http://www.astroflight.com/index.php...roducts_id=102

-Rich.

niteshadow

mmmmmmmmmmmm nice wonder if a weedeater motor that i heard some are using???????????????
have nice day
art

Kmot

My Feedback: (24)

I expect you will need at least another 200 lbs. of ballast to get an 8' PT hull down to the water line! [X(]

mfr02

Nah. Let it sit high like its coming home with light tanks.
Like Colin Chapman (Lotus) used to say "Add more lightness".

pblix

I think your weight estimate is accurate. The original displaced approximately 50t - which at 1:10 scale is 110lbs.

In situations like these, I use the full size boat power rating and convert to rating at scale and under "scale speed". Bear in mind though, that a scaled down power train may be less efficient than the original, so the result is before losses.

Depending on version, the Elco 80s had 3x 1200, 1500 or 1850HP. At 1:10 scale that converts to 3x 1.2, 1.5 or 1.85HP. If you go with two motors they need to be: 1.8, 2.25 or 2.8HP each respectively. Add 25 - 50% to overcome the efficiency difference. So, it looks like you'll need 3x 2HP motors.

Those are big motors. I'd look for DeWalt Hammerdrill replacement motors. I'd run them at 24 or 36 V. You're getting into Robot Wars territory. There are plenty of retailers in that area - most notibly robotmarketplace.com. Nextup is ESC - prepare to hand over your wallet!

All the best.

DJLaPalme

No matter how I power it it is going to be an expensive project. I want everything to be as scale as possible, including working torpedos and tubes or racks. This is going to be quite the challenge. Thanks everyone for your inputs. I'm sure there will be bigger challenges than the power plant to think about and I'm sure there are plenty of people with much greater brains than mine to help. Dennis

Rich404

Hey DJ,

When you get started definitely post pictures of your progress. This should be a pretty cool build.

-Rich.

mfr02

How did real life PT boats run their power?  All three motors running permanently? Wing motors or just the center motor for cruising and the other(s) for the extra speed when needed?

Apismelifera

MFR02 Hi there.

From what historical accounts I have read whenever they were in or near enemy waters all three engines would be running. Usually only one was actually propelling the boat the other two would be idling in neutral when traveling at slow speed. Then the other two could be engaged and throttle up at a moments notice. No worrying about start up time or waiting for it to warm up. All at the Captains discretion of course.

blizard05

I would look at 2-3 auto heater fan motors?

pblix

I'm not sure where you'll find a 2+ hp auto fan motor. At 12V & 10A (guess) you're only getting 120W, which is about 1/6 hp. Not nearly enough. Even Scooter motors only go to about 1 hp.
My vote is still with a set of High-End Cordless powerdrill motors.