Complex sentence: By 1945, she was permanently installed as a replacement of the Lightvessel "Kiel", which had been damaged by British planes, but in the spring of 1957, she was rammed by a Swedish Freightship and sank.
Split into simpler sentences: By 1945, she was permanently installed as a replacement of the Lightvessel "Kiel", which had been damaged by British planes. In the spring of 1957, she was rammed by a Swedish Freightship and sank.