Complex sentence: The USCGC Bittersweet (WLB 389), a "C" Class (Iris) buoy tender and was built by the Zenith Dredge Company in Duluth, Minnesota.
Split into simpler sentences: The USCGC Bittersweet (WLB 389) was a "C" Class (Iris) buoy tender in service with the United States Coast Guard. She was built by the Zenith Dredge Company in Duluth, Minnesota.