Maarten Peter Pieterse, 59, and Emile Adriaan Jeroen Schoemaker, 44, were on the Netherlands-registered SY Marcia when it was intercepted off the coast of Cornwall on Wednesday.
The boat was escorted to Newlyn in the county, with the National Crime Agency calling the operation a “signficant seizure of cocaine”.
It was listed in court that at least 1.6 tons of cocaine has been removed from the boat, but the exact quantity recovered has not been disclosed.
The amount has been described as one of the biggest ever hauls of cocaine off the coast of the UK.
Pieterse and Schoemaker appeared at Bristol Magistrates’ Court via videolink from Camborne, Cornwall, for their brief hearing.
The pair are accused of being “knowingly concerned in the carrying or concealing of controlled drug of Class A, namely cocaine, on the SY Marcia knowing or having reasonable grounds to suspect that the drug was intended to be imported or had been exported contrary to Section 3(1) of the Misuse of Drugs Act”.
Pieterse and Schoemaker spoke only to confirm their names, dates of birth, Dutch nationalities and to say they did not have UK addresses.
Andy Young, prosecuting, said: “The searches are ongoing and therefore more may be on there. Two crew members were on board.”
Solicitors representing the two defendants did not make bail applications and they were remanded in custody until a hearing at Bristol Crown Court on 20 August.