In 1867, an inventor, Willem Hendrik ter Meulen, proposed using a 'zandboor' ('sand drill'), "a device which forced water into the sandy sea bed in order to clear a way for a helmet diver" and signed a three-year contract, subsequently extended for another three years and then a further twenty years. The plan was that when the depth of water reached , the machine would be used to excavate the same depth of sand down onto the wreck. Ter Meulen bought a steel-hulled, paddlewheel-driven 50 h.p. steam tug, "Antagonist". The engine was modified such that it could be disconnected from the paddlewheels and used to drive the centrifugal 'whirlpool' pump. The pump was capable of pumping water at a rate of , but tests showed that was sufficient, and the 'zandboor' took only a couple of minutes to penetrate through to the wreck. It was also found that the sand did not collapse once the diver descended through the drilled hole into the cavity excavated by the machine.