At 01.01 hours on 23 Nov 1940 the Ootmarsum (Master J. de Vries) in convoy SC-11 was hit by one torpedo from U-100 from a distance of 600 metres and sank by the bow immediately. She sank so fast convoy commodore was not even aware that the ship had been sunk.

Type: Steam merchant
Built: 1920 - A. Vuijk & Zonen, Capelle an der Ijssel
Owner: Stoomvaart Mij Oostzee NV (Vinke & Co), Amsterdam

Tonnage: 3,628 tons

• Haersolte, J.W.J. van (1947).
  Scheepsrampen in oorlogstijd, no. 5.
  J.F. Duwaer & Zonen, Amsterdam.
• Uboat.net.
  uboat.net.
• Maritiem Historische Data ID 4923.
  Stichting Maritiem Historische Data.