Complex sentence: When Rio was finally sighted on October 13 the remaining crew were too ill to bring the ship to port; instead she drifted helplessly in the outer harbor until Rio's harbourmaster sighted her the following morning and had additional seamen rowed out to assist.
Split into simpler sentences: When Rio was finally sighted on October 13 the remaining crew were too ill to bring the ship to port. She drifted helplessly in the outer harbor until Rio's harbourmaster sighted her the following morning and had additional seamen rowed out to assist.