The former senior lecturer at Gloucestershire University set off on her journey from Dartmouth, Devon on 24 October.
Ms Melling said: ‘I am very excited to be taking on this challenge, as it will be fulfilling a lifelong ambition. And I am very happy to be raising money for the vital work the QNI does for community nurses.'
She will be joined by three other crew members and a skipper aboard the Bold Explorer, a 45-foot steel yacht.
The trip is expected to take between 34 and 50 days.