How Much Force Is Needed to Retrieve a Sunken Barge on a Rocky Slope?

[Gunter]

i am in guatemala and i have a barge that sank at the shore line, and i need to pull it out and cut it up
it is made of steel 160' long 69' wide and 1500 tons
it sank on a 30 degree incline rocky bottom

how many tons of pull do i need??

 

[JaredJames]

Well this would really come down to the friction on the bottom.

If the bottom of the boat is smooth and not snagged on anything then it should be simply:

mgCos(30) = force required to move boat ignoring friction

Where m is mass of boat (not weight) and g is gravity.

If you know how easily the boat slides over that surface then you can add an appropriate approximate figure for that and then you need to allow for resistance through the water (again a reasonable amount will suffice).

Assuming it's metric tonnes, 1500 is 1,500,000kg.

That gives you:

1.5E6 * 9.8 * Cos(30) for the minimum required force, plus water and sliding resistance approximations.

Which is ~12.74E6 Newtons of force required plus water and sliding resistance approximations.

At lest that's a quick calculation if I've approached this right.

 

[Gunter]

now how do i calculate that to tons of pull,
i don't want to move it fast,
i yost want to pull it with some big winches and lots of parts

 

[JaredJames]

Sorry, messed up the calculation, here's the correction:

Because of the incline you're going to need at least 750 tons to get it out.

When you factor in resistance, you're probably looking at a value of at least 800+ tons.

I'd probably say at least 900 tons to be safe.