At 20.15 hours on 5 March 1940 the Grutto (Master B. Kuiper) was spotted by U-17, heading east-northeast with all navigation lights burning. At 20.40 hours, a first torpedo missed but the second fired 18 minutes later struck the ship amidships and broke her in two. The stern section sank within one minute and the bow followed six minutes later.

In the early morning of 6 March, a ship of the Dutch ’ Batavier’-line spotted wreckage and a raft marked Grutto 7.5 miles southwest of Thornbank. The Belgian pilot boat Loodsboot No 8 also reported this raft and later picked up debris two miles west of the Belgian lightship Wandelaar. This wreckage was later identified as belonging to Grutto. Loodsboot No 5 salvaged the raft and delivered it to Oostende. On 29 March, the bodies of two crewmen washed ashore on the Dutch coast, the body of sailor B. van der Spek near Callantsoog and the one of first steerman R. Teensma on Texel. Both were identified by their families.