Complex sentence: In the 1950's and 60's, astrodomes were gradually phased out, as radionavigation and ground plotting radars took over, but enjoyed a second career on ocean racing yachts (specially in singlehanded racing).
Split into simpler sentences: In the 1950's and 60's, the use of astrodomes in aircraft was gradually phased out as radionavigation and ground plotting radars took over. Astrodomes did, however, enjoy a second career on ocean racing yachts (especially in singlehanded racing).