David Halpin, 62, from Haytor, Newton Abbot, is leaving on Saturday with a consignment of food, clothing and medicine aboard the 200-feet-long Danish-based cargo vessel, the Barbara.
He and three other crew members will be making the 3,000-mile journey with about 55 tonnes of cargo.
The vessel will head from Haldon Pier in Torquay for the Israeli port of Ashdod, near the northern border of the Gaza Strip.
Mr Halpin will be accompanied by Stuart Lawley, 24, from Dorset, and John Maughan, 55, from Boscastle, Cornwall.
Also going is John Hingley, 51, a Brixham trawler skipper, whose vessel was to be used for the voyage until it was ruled out by coastguard regulations.
Mr Halpin said: "My motives are not based on politics or religion. The idea is to drive a wedge into people's awareness.
"We are sailing as ordinary people to meet ordinary people in Gaza."
Mr Halpin's mercy mission is costing him personally about £95,000.
The aid is intended to help the 1.1 million Palestinian refugees from Israel who live in Gaza.
Aid being taken includes 40 tonnes of flour, one tonne of Cheddar cheese, five tonnes of milk powder, 1.4 tonnes of wool and £1,500-worth of donated medical dressings.
Mr Halpin, who has so far received donations of £15,000 from supporters around the country said they expected to sail at 1700 GMT on Saturday.
The Barbara will fly a 75-foot banner reading "justice, peace, brotherhood of man".
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