The service of Richard Musgrove on the Laconia when commanded by Capt. Wentworth seems an irony of situation by the narrator.
Mrs Musgrove retaining her son's letters and service under Capt. Wentworth provide an additional reason for the Musgroves to decide to invite him to the Great House after he arrives. (ch.6)
Meanwhile, Capt. Wentworth is a topic of conversation in the social circle Anne has entered at Uppercross.
Poor Dick's lack of ability as a successful seaman, by contrast, enhances a sense of Wentworth's resourceful & inspiring charecter.