New information. Family from a former member of a British disposal team that had redered safe a German Torpedo Mine at there Waal bridge at Nijmegen in 1944 told my contact the following:
I believed the charge to be a magnetic mine Type C which has been modified with a flotation chamber at each end.
So a GC Mine (Luftmine B) with two floating chambers. has someone a picture?
Antoon, I'm not aware of any picture of the to-minen, neither from books, manuals or archives. I've actually looked for one for many years.
As already mentioned, the system underwent a development period and different models were devised and used during the operations.
The early idea was to adapt a TMB mine case (model 2 or 3) with two floating ends, the first models were designed for sea water and used to sink due to lack of buoyancy in riverine operations, dimensions and shape changed, from a cylindrical system the last developement devised a shape like the hull of a ship, described in the documents as pointed, flat on top and rounded at the sides. The explosive was Nipolit, 600kg in the system used during the Waal operation, documents states that clockwork was the Italian 10 hours which the Operators used to be familiar with during the training in Italy, also adopted on the minor charge (the Sprengfische). It is yet unclear which 10 hours clockwork was actually fitted on the to-minen as the said device comed with three different cases. It is also unclear if a second device was fitted. I've found a reference also to a 6hrs clockwork but it is unclear which model used to be fitted with it.
In my opinion more context is needed, during the Waal operation one to-minen stuck on a sand bank and was indeed rendered safe, unfortunately I don't have the report of that activity, it must be buried in some generic file at TNA. The Royal Navy Minewarfare & Clearance Diving Officers' Association has published a list, not comprensive but a good starting point, of the awards for ordnances disposal, is it possible to know the name of the man you're on about?
Attached a sketch of commander Hummel of the to-minen configuration during the Waal operation, the mine that was rendered safe was one of the two destined to the road bridge.