Barge Problem

I have a large barge that I want to move across a lake using a cable winch.
My problem is I an designing the winch and I need to know how much torque I will need to move this barge through the water at 7 knots The barge weighs a couple hundred ton when fully loaded
I hope to do this with a cable winch using 1.1/4 dia steel cable.
any help or ideas with this would be gratefully accepted

 

Mr Mann, how often do you want to move the barge & how far across the lake? Is this like a vehicle ferry, 7 knots? I haven't got any answers, i think more info is required. All the best from Jeff.

 

Without a fair bit more information about your barge, you'll get very little helpful information. I can say that even a tugboat tow of your barge will likely not get 8 MPH. The breaking strength of your cable (about 65 ton) suggests you need a marine engineer look over you ideas at the very least.

What are the physical dimensions of the barge? Is it well sloped fore and aft? How long is the tow, the general conditions on the lake, current, winds, etc., etc. etc.

Given that 1.25" cable will weight about 2.5 pounds a foot, it's pretty simple math to figure a very long tow, will need one hefty *** spool to wrap it up on, not to mention an engine to drag the 100 tons of barge and cable weight across. Have you considered just mounting an engine on this barge or using a push boat?

 

...yeah, as PAR says, the best way to run a barge is self contained motor on board, it then only lifts the cable as it is needed, no big reel needed and the catenery of the the cable is the tension needed to drive the powered wheel.....the speed may not be attainable economically...we have many river crossing ferries in this part of the world, and they are ALL powered this way....for a good reason I would suspect.

 

Also find out how to stop it.

 

The barge is being pushed by a tug now and we feel it would be more economical to pull it with a cable winch as I have seen used on other applications like ferry boats.
The winch would have two large bull wheels and can be powered by a large hydraulic motor . the lake is calm and the distance is aprox one mile, I will check the size of the barge but I think it is 60 X 30. It is sloped front and aft. Basicly what I am looking for is how much torque is requied to pull so I can size the hyd motor

 

Well, how much HP was the tug?

-jim lee

 

That's at least 7 tons of cable! 8 MPH is out of the question, though a barge mounted engine and cable drive is an option, not a good one, but certainly a possibility. What level of durability are you looking for? How often will you use it?

 

About 35 000 foot-pounds of torque to attain 7 knots.

Best of luck.

-Tom

 

The amount of torque needed depends on the tension in the cable, the gear reduction in the winch, the maximum diameter of the cable on the drum, and the efficiency of the winch.

The tension on the cable will depend on the resistance of the boat plus the effects of the weight of the cable. By the way the effect of the weight of the cable on the tension is not as simple as added tension equals the weight of the cable. That's only true if the cable is hanging straight down. Otherwise it depends on the angle of the cable. As the cable moves away from vertical the tension due to the weight increases, and as the cable approaches horizontal.

How familar are you with engineering statics?

 

Some cable ferries I've seen use the cable to guide the ferry, while propulsion is by an engine driven propeller.

Winch on the barge pulling the barge along the cable which is fixed to shore, or winch on shore with the cable moving?