# Seeking information for this build



## WolfTronix (Feb 8, 2016)

Two 12V trolling motors, one for each wheel.

Replace the prop with a pulley or sprocket to drive the wheels.

Built in speed controllers and they are already water proof.


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## dcb (Dec 5, 2009)

the down-angle force of an object is the weight * sine(angle)

so that if you have a 200lb boat, and it needs to climb a 30 degree ramp, you will need 100lbs of push, just to hold it there (generally speaking, inertia and friction and etc are factors).

so, 100lb force at 3mph is 0.8 hp (440ftlb/sec), or 600 watts minimum, probably a bit more just to be sure. The next thing is determine the wheel diameter and select motor/gearing/voltage appropriately (maybe motors ride high up and/or in front and chain drive the wheels). It isn't going to see a lot of use, so keep it cheap and simple.

at 12v you are going to need 50 amps minimum (12v * 50a = 600 watts), probably 100 to go 3mph up a 30 degree hill.


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## major (Apr 4, 2008)

Power just one wheel? Perhaps in the center with like training wheels each side. Maybe a little scooter wheel motor? Low voltage motors can dunk; no worry. Or maybe a powered steering handle opposite end from current wheels? Seen those for big trailers. Just a smaller version. Perhaps use wheel/axle/gear/motor and control from handicap scooter. Or tow it with golf cart, like all the dads do at jr dragster races. Pit toys can be a lot of fun.


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## Duncan (Dec 8, 2008)

Hi
I would be inclined to have a look at electric wheel chair bits - make a simple cart using the wheelchair bits and lever it under your trolley when needed,

3mph is a decent walking pace
1mph is a more sensible moving a boat up a steep ramp pace - which cuts your power down accordingly

The ones I was looking at were about 80 watts each - 3.5amps at 24v
Use a couple of 12v batteries - simple car batteries would do as you are NOT using much power for very long

These motor units are worm drive which gives a good reduction BUT they will NOT freewheel - which is probably a good thing for shifting something heavy up or down a ramp


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## Ram4x4 (Jun 28, 2016)

Thanks guys, I'll take it all and figure out what I need.

Unfortunately, using a golf cart or an ATV to pull us up is a no-go, not allowed at the sites.

Can't use a tractor type set up on the front as the overwhelming majority of the weight is in the back. I've intentionally put some slight over hang on the back, so the weight of the motor and the boat slightly offset to the rear, only takes about 15-20lbs to lift the front.

The center wheel idea is interesting, would have to see how it complicates the build.

The wheels (with tires) are 16" diameter. Some guys use 13", or even 10". I find the larger diameter rolls better.

Wondering now, based on the wattage numbers if 12v is going to be enough? That's a lot of amps! Doubling that to 24v now means two batteries which makes the "power pack" heavier.

Since most small electric motors turn high RPM, that's a lot of RPM I can convert to torque output (HP = torque x RPM divided by 5252). 

Drive mechanism needs to be able to engage and disengage as it is only needed going up the hill, then just pulled along manually on flat ground, that's why I was thinking a friction roller mechanism controlled via a lever at the front.


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## Ram4x4 (Jun 28, 2016)

WolfTronix said:


> Two 12V trolling motors, one for each wheel.
> 
> Replace the prop with a pulley or sprocket to drive the wheels.
> 
> Built in speed controllers and they are already water proof.


I like the idea, but are they powerful enough?


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