5hp Homemade Ski Rope Tow

Given the rather slow speeds that these types of towing systems go, 1 -2 MPH most definitely!

Are you sure you want to design it for use by only one person at a time? Why not give it the power to handle 2 or 3? Then they could race each other without having to wait, or just less waiting in general.

You just reminded me how excited I should be to get to the slopes...

I have 2 words for you,,,liability insurance....

Having said that, I offer this.....The Magic Carpet....

Can a 5hp ICE pull a nominal mass person up an incline plane 250 feet up in elevation? Certainly this can be done. 5hp is a small but common size engine for a riding lawn mower. Can I say if your design and fabrication skills are up to this task? I cannot say since neither are evident. Can this be done in an expedient, cost effective fashion so that a snowboarder will prefer this to walking? It probably can be done but again a suitable design and the snowboarder patience are not evident. Can this be done with absolutely no regard to safety, leading to tragic bodily injury and attorneys profiting from tragedy? Absolutely this can happen. You can also be lucky and never have a bad design turn into a tragedy. If you didn't have to ask us such a basic question, I would be much more confident that you can do this safely.

Good Luck

Why re-invent the wheel?: http://www.capstanropewinch.com/

Many others available, often used by mountain rescue teams for vertical pulls, so higher speeds possible on the slope you intend to use.

If you know of a rope slicer, then a continuous loop is possible.

Rope Splicer, I think. A riding mower could be used, all by itself. Big soft tires, lots of tread, chains...

Horsepower is just time rate of doing work. What's the VERTICAL lift, coefficient of friction for a snowboard, speed desired, etc. Don't forget a stripper on the rope to keep fingers out of the driver pulley, which could be the big v-pulley on a clothes dryer, lashed to a drive wheel on the mower. The differential might blow out, though.

5hp @70% efficiency represents a rate of increase in potential energy of _{<...tap, tap..press equals...>} say 2600J/s.

Raising 150lb or _{<...tap, tap...press equals....>} 67.5kg or _{<....tap, tap...press equals...>} 662N, divided into 2600J/s is, er _{<...tap, tap ...press equals...>} a maximum rate of rise vertically of 3.9m/s.

So at first sight, yes, the engine seems powerful enough to do the job.

Do make sure there is sufficient professional indemnity insurance cover in place before using the equipment for real.

It is very risky to pull people up on single rope winch. What happens if brake, rope, gears fails. Is there any safety measures?.

Put a T bar T at the lift end.

I'd be very concerned about the kid's hands and arms getting in the uphill pulley arrangement.

Major Safety & Liability issues!

I can just see this featured on "A Thousand Ways to Die" LMAO!

Or The Darwin Awards!!!!!

I hate the fact the human race has been wiltered down to (synonym for feline) because of the over population of lawyers.

ingenuity has been replaced with the ability to make an app for the envolving future human that has no voice box, is slouched over cro-mag style with most of its ability and dexterity in its thumbs.

Sounds like a great idea and you shouldn't have any problem experimenting with some gearing to make it work well.

We have a Christmas tree farm and we use an electric motor running a gear reducer to pull the big trees through our netting cone. We pull a tree that is 7' in diameter through a 24" netting cone. It works great and has plenty of power. That is a lot more force required to do that than there will be to tow a kid up the hill. We wanted to make it pull a little quicker so we changed the size of the pulley.

Just put some safety features in place on the uphill side where your engine is so nothing can get pulled into a sheave/pulley. Shouldn't be hard at all. It sounds like a good father/son project.

At the top of the hill, run the rope through a piece of plywood at least 1x1', with a hole just large enough for the rope to go through it, with a nylon bushing in the plywood to protect the rope. This should prevent anyone's hands or fingers from getting caught in the winch. Mount the plywood on a stand, or stake it into the ground.

As with a lot of warnings already beware of the liability. I had an unfortunate incident as a 5 year old youth when I had my skis kick out and the rope from the tow ran over my cheek (nice rope burn) and the other people on the line ran over me. Rope burn and embarrassment is all that I received but I guess it could have been worse. So no matter what you do keep safety in the forefront.

I know, I know all you guys are all looking up to the right now thinking OH thats whats wrong with him.........

Well done. I like the spring loaded sheaves to help retain the line on track while allowing a handle to pass through. Although it's been about 35 to 40 years since I used a rope tow, those all were just large diameter three-strand rope lay that you grabbed with your gloves. Weak grips need not apply as you would get rope burned palms in a matter of a few seconds. Grips spliced into the line would go a long way towards glove longevity.

Cheers!

Could you please post a link to where I could purchase those springs and jockey wheels as well as any other information that would be helpful to build that piece of the system?

Thanks, Ted

Amazing responses thank you guys so much. And for all the worry warts here. The 'kids' using the rope tow are high school kids with years of snowboarding experience under their belts. If they can jump a 40ft gap through the air I'm sure they're capable enough to know when to let go of the rope. The basic setup is a post and pulley at the top and middle of the hill (where there is a change in grade). With the motor and gear reducer at the top. I was mainly concerned whether or not that 5hp had the juice to do the work before I put any cash down. When all is said and done I plan on taking video and pictures of my setup and will share with everyone. Total cost will probably come to a couple hundred bucks, maybe. But thats because of family and friends generosity and access to material.

Assume the efficiency of the Stration engine is U , and if F is the force exerted by the machine on the boy, the work done to tow the boy =5x746U joules=3730U Watts

250feet= 250x 12x 2.54cm=76.2metres

Therfore, 76.2F= 3730U

F= 3730U/76.2=48.95U Newtons......(1)

Assume the angle of the hill is Q.

Force of friction= WEIGHT OF BOY x Acceleration due to gravity x sinQ

=150/2.2 X 9.8 x sinQ

=668sinQ Newtons..............(2)

Net force pulling the boy uphill = 48.95U-668sinQ

Since the hill is steep, we can assume maximum friction force, hence Q=90degrees

Hence we get,

Net Force on boy up hill=48.95U-668 Newtons

If 48.95N is greater than 668Newtons, then it is possible to pull the boy up hill.

This will be determined by the efficiency (U)of the Stration engine.

The minimum efficiency required of the Stration engine should be at least 15%.

If the efficiency of the Stration Engine satisfies this condition, then it can pull the boy up hill.