2 ms·
Just an order of magnitude viz-a-viz a winch: -- the Ever Given has a mass of ~220,000 tons (2.2e8 kg) -- let us very conservatively assume that it is a homog
by azalemeth 6y ago
Just an order of magnitude viz-a-viz a winch:
-- the Ever Given has a mass of ~220,000 tons (2.2e8 kg)
-- let us very conservatively assume that it is a homogeneous block, 1/3rd of which is on sand, 2/3rds of which is on water
-- the Coulomb coefficient of friction for steel on sand is a very complex function of sand composition and size, but roughly it's about µ=0.5 and F=µR [1]
-- For the 2/3rds of the ship that are in the water assume that it moves frictionlessly in an inviscid liquid (not true at all else ships wouldn't have huge engines!)
-- You therefore need to apply a net tension of ≥0.3 x 0.5 x 2.2e8 ≈ 33 MN to a wire to have a remote chance in hell of accelerating the ship backwards
-- This is about twice the thrust of a Space Shuttle solid rocket booster at liftoff.
[1] https://www.jstage.jst.go.jp/article/sandf1972/26/4/26_4_139/_pdf/-char/en https://www.jstage.jst.go.jp/article/sandf1972/26/4/26_4_139...
- deleted 6y ago[deleted]
- wildthought 6y agoThe weight on sand equals the weight of the portion of the ship that has been raised above sea level by the collision. The bow appears to have been raised, but not the stern. The lift is by about 10% of the ships height (or less), so 5% on the average of the ships length. That cuts the above estimate by a factor of 6. The remaining required force could be provided by a number of winches of a pull of 1000 tons each operating from the opposite bank of the canal and pulling in the direction opposite to the ship. Tugs would then have to turn the ship straight as soon as it starts getting afloat.