Complex sentence: Out of the shipyard by 20 December, she sailed west on the 24th; she joined ServRon 6 at Pearl Harbor on 2 January 1944, and on the 21st headed for the Gilberts.
Split into simpler sentences: Out of the shipyard by 20 December, she sailed west on the 24th. She joined ServRon 6 at Pearl Harbor on 2 January 1944, and on the 21st headed for the Gilberts.