The boys in the Lynx use a map and a dalton computer. The Dalton is particularly good when working out the PNR, CP and ROA....particularly when working them out towards and from moving waypoints.
The trick is knowing where the ship is going to be when you return from your sortie but there are ways and means to arrange an RV in the middle of the ocean. The Lynx Observers work would be helped if the aircraft had an integrated GPS system. Some of the aircraft do but sadly most of them don't and the Observer spends his day updating the nav kit from a stand alone GPS......much the same as people did in the olden days.
Hmmmmmm.