Ship bending due to wave motion

Modern container ships are made from welded steel plates and can have length of up to almost 400 m. They carry huge numbers of inter-modal containers (which can also be carried by truck or train).

The first container ships were converted world war 2 T2 tankers typically 152.9 m in total length and 20.7 m in width (beam). The largest container vessel today is MSC Oscar, 395.4 m in length and 59 m wide and capable of carrying 19224 containers (TEU — twenty foot equivalent unit).

As these ships travel the globe they are bashed by waves, in this video we can see the displacements this causes inside the vessel.

Video shows the container ship MSC Busan in heavy seas. In the video at around 11 s a wave of height approx. 7-8 meters hits the vessel.

More links


Biggest Ship ever

The largest ship to date is was the Seawise Giant built by Sumitomo Heavy Industries at Oppama shipyard. A ship so big that it takes Top Gear presenter Jeremy Clarkson to describe it.

Seawise Giant had several names since it’s building from 1974-1979 and it’s scrapping in 2009, including Knock Nevis. Here is a comparison between some of the other largest ships in the world.

The largest ships so far.

The largest ships so far.

Seawise Giant was the longest ship ever constructed, longer than the height of many of the world’s tallest buildings, larger than the Petronas Twin Towers at 451.9 m (1,483 ft). In December 2013 Prelude FLNG became the longest ship ever constucted which measures 488 m (1,601 ft), built by Samsung Heavy Industries at Geoje Shipyard. Also four Batillus-class supertankers operated from 1976-2003 built at the Chantiers de l’Atlantique shipyards in France which had a larger gross tonnage.

The Pentagon, 431 m   RMS Queen Mary 2, 345 m, USS Enterprise (CVN-65), 342 m, Hindenburg, 245 m, Yamato, 263 m, Empire State Building, 443 m, Knock Nevis, ex-Seawise Giant, 458 m

The Pentagon, 431 m
RMS Queen Mary 2, 345 m, USS Enterprise (CVN-65), 342 m, Hindenburg, 245 m, Yamato, 263 m, Empire State Building, 443 m, Knock Nevis, ex-Seawise Giant, 458 m

Bainite in Steels

Harry Bhadeshia’s book Bainite in Steels has reached it’s third edition. It’s available on pre-order at a price of 80 UKP and will be available from April. The third addition has an additional 40% more content to cover the developments of the 15 years of research since the previous edition.

This book is highly recommended for those who have an interest in the physical metallurgy of steels, alloy design, and solid-solid transformations.

Cover image for Bainite in Steels, 3rd Edition.

Cover image for Bainite in Steels, 3rd Edition.

Metal working machines

Hebo machines have posted a nice video showing various machines for cold forming steel.

Completely unrelated, this is beautiful machine too, desktop injection moulding:

Making a welded Damascus Knife

John Neeman Tools have posted a beautiful video of manufacturing a welded Damascus patterned knife.

5 layers of 3 different steels were forge-welded, folded, and forged. With each step being repeated 8 times. This produces a patterned with 320 layers. Finally twisting and forging the steel produces a more complex pattern.

Just checking the number of layers, I get their total to be different. My calculation of the number of layers is 5 × 28 = 1280, that is 4 times more than claimed (320 layers should be the result of folding 6 times (6 folds 5 × 26).

With 1280 folds, if we assume the thickness of the knife is 2 mm, that means each layer is 1.6 μm, 320 folds would be 6 μm layers. These are both lower than what can be resolved using the naked eye. It’s very close to the wavelength of visble light — if the metal were folded one more time, or the final thickness of the knife is less than 1 mm you would be there.

Hadfield vs Hatfield

I always get these two Sheffield related names mixed up.

Hadfield Hatfield
Sir Robert Abbott, Baronet Hadfield Dr. William Hatfield
Inventor/ manufacturer of high Mn
steels known as Hadfield Steel
Inventor in 1924 of 18/8 stainless steel, and 321 stainless steel (18Cr-8-Ni+Ti).
1858-1940, Born in Sheffield, Died in Surrey 1882-1943, Born in Sheffield.
Son of Robert Hadfield
Wrote over 200 Papers Authored many papers.
Made Hadfields foundry one of largest in World Appointed director of Brown-Firth Research Laboratories (succeeding Harry Brearley)
Hadfield steel can also refer to some high silicon steels  Stainless Steels and also some high temperature alloys were developed by Hatfield (12Ni-5Mn-4Cr which has high thermal expansion coefficient and 5Ni-4Cr-3Mo which has strength at high temperature).
Obituary Obituary

Sharks attracted to steel

Cage diving was invented by a diver who survived an attack by a shark. Wanting to return to the sea he was inspired by the lions cage in Melbourne zoo.

At first it was thought the sharks were attracted to the people in the cage, but later it was observed that sharks also investigated empty cages. It turns out that they are attracted to the steel. I wonder if this is electrical effect, or if they are usually attracted to the iron in blood? Dissolving iron from the cage may seem similar to haemoglobin.