Degaussing WW-2 Submarines.

[Flogger15]

Just finished the book "Thunder Below" by Admiral Gene Fluckey who commanded the USS Barb on 5 cruises during WW2. It was a Gato class submarine. They mentioned having to 'Degauss' the submarine right before leaving Midway (after fuel/torpedo reload) for the sea of Okhotsk. I knew degaussing was a counter measure against magnetic mines but really didn't know how they did it.
Many ships were retrofitted or built with the degaussing generators & wiring on board. The USS Barb was built without it and, from what I understand, had to degauss every 6 months. I still don't understand the process, not much info online.

 

[OliverSedlacek]

Electromagnetic degaussing can be performed by putting an object in a coil that applies an alternating magnetic field to magnetise the object in alternating N-S-N-S directions. The applied field is gradually reduced in strength down to zero, taking the residual magnetisation in the object down with it.

 

[TJDougherty01]

Modern submarines undergo degaussing in purpose built facilities

 

[ArmchairSamurai]

Just finished the book "Thunder Below" by Admiral Gene Fluckey who commanded the USS Barb on 5 cruises during WW2. It was a Gato class submarine. They mentioned having to 'Degauss' the submarine right before leaving Midway (after fuel/torpedo reload) for the sea of Okhotsk. I knew degaussing was a counter measure against magnetic mines but really didn't know how they did it.
Many ships were retrofitted or built with the degaussing generators & wiring on board. The USS Barb was built without it and, from what I understand, had to degauss every 6 months. I still don't understand the process, not much info online.

Not much help but this may give you an idea of how it looked... The only real picture I know of that shows it on a ship during the war. If anyone else has anything else to offer, please do, because I would enjoy seeing it too!

 

[Scott Kenny]

I think everyone here is aware of the issues the US Mk14 (and Mk15) torpedoes had in WW2. Part of that was due to the different strengths of the Earth's magnetic field in different places.

So one of the things you can do is to degauss the ship based on where it's going to be, to have the smallest impact on the global magnetic field.

 

[Roodbaard1958!]

Dutch floating sheerleg Walcheren, later sold to Russia (https://warshipsresearch.blogspot.com/2016/06/dutch-floating-sheerleg-walcheren-1945.html) towed by Dutch tug Delfshaven to the station at Rotterdam to be demagnetized on 13-12-1949. Photo Zeeuws Archief, archive shipyard Kon.Mij. De Schelde (nowadays Damen Naval) : https://hdl.handle.net/21.12113/029FA7EDF506490E91E52C4346988730


In this link in Dutch (use translator) is described how this station operated: https://onzemarinevloot.weebly.com/demag-dependanche.html

 

[Flogger15]

I found this from an online article, I had no idea how involved it was/is.

" A ship is basically a bar magnet with a North and South Pole. A vessel begins to acquire a magnetic signature as soon as the keel is laid. Whether or not perfectly aligned with the Earth’s magnetic field at any given location (reversed south of the equator), the ship acquires a unique magnetic signature."

And THIS!

" Including components of the Earth’s magnetic field, other factors will contribute to induced magnetic fields of surface vessels, and where applicable, submarines, which require countermeasures to their magnetic signatures. These include the firing of a ship’s guns (for example, the 16 inch guns on a battleship), firing torpedoes, the pounding of the ocean waves upon the vessel, changing barometric pressure, variations in the salinity of the water, firing of antiaircraft guns, depth charges near submarines, and the flow of current in various electric circuits and machinery aboard. Ambient air and water temperature also affected the magnetic signature."