The shipbuilding yard of Ramage and Ferguson in Leith (Scotland) was charged with the building.
This barkentine with its gross tonnage of 778,26 t. which is fitted with an auxiliary engine of 500 h.p., has an over all length of 78,40 metres and a beam of 11,09 metres. Its draught was 4,50 metres. The Mercator is rigged as a barkentine. This is a composite rigging, the foremast carries square sails, the main mast and the mizzen mast are rigged with fore and aft-sails. Usually the Mercator carried 15 sails with a total surface of about 1600 m². By fair wind, the Mercator could easily run 13 knots.
The 7th cruise was doubtless the most remarkable amongst those proceeding World War II. This dream voyage lasted from October 3rd 1934 till May 21st 1935 The actual place of destination was The Easter Island tot pick-up a Belgo-French scientific expedition but at the same time Pitcairn Island, Tahiti, Papeete, the Marquis Islands and Honolulu were called at.
In 1936, the Mercator was done the honour to bring over to Belgium the mortal remains of the Flemish missionary and apostle of the lepers, Father Damiaan, who died on the Molokai Island in 1889.
On February 21st, 1940, the training ship left the port of Ostend. After a voyage to Rio de Janeiro, the Belgian ship arrived in Boma. This was the end of the twentieth, and at the same time the last cruise before World War II. Early 1943, the schoolship was summoned by the British Admiralty and left under the British Flag as a “Submarine Depot Ship” for Freetown, where it stayed till August 1945. It was only on January 18th, 1947 that the Mercator, taken in tow by the “Empire Mary”, sailed on the River Scheldt again. Nothing was left from the formerly elegant and well maintained training ship.
After World War II, the Belgian training ship put to sea again on January 20th, 1951.
The Mercator was in service as a training ship till August 1960 and made 41 voyages altogether, during which almost all seas have been sailed on and a great deal of ports called at.
The Mercator accomplished many scientific missions and many times represented Belgium abroad. The ship participated also to the great sailing races, such as Torbay-Lisbon (1956), Brest-Canary Islands (1958) and Oslo-Ostend (1960).
All those years that the Mercator was in service as a training ship, is was under the command of Captain R. Van de Sande (from 1932 till 1955) and of Captain R. Ghys (from 1955 till 1960).