In what is thought to be the first prosecution of its kind in the Defence Forces, the sailor is accused of leaking sensitive information on the movements of naval vessels.
The Naval Service’s eight vessels patrol waters around Ireland in what is the front line against drug traffickers and smugglers of other illegal goods.
The Defence Forces have previously said that the allegations emerged during “regularly conducted security checks” conducted by Naval Command.
While the exact charge won’t be disclosed until the court martial, the seaman is accused of passing information to unauthorised persons.
His case was mentioned in court at the naval base at Haulbowline, Co Cork, last Friday week.
Such “mentions” deal with preliminary matters of the court martial, such as setting the date for trial, disclosing of documents and application for legal aid.
As a result the court martial was set for April 13 at the Military Justice Centre in McKee Barracks, Dublin.
The sailor is being prosecuted under a limited court martial. A member convicted of an offence under this court can face a maximum prison sentence of two years.
The Director of Military Prosecutions (DMP) directed a limited court martial, which is between a summary court martial, that deals with minor offences, and a general court martial, that deals with serious crimes, such as murder.
The DMP, which is the military equivalent to the Director of Public Prosecutions (DPP), made the decision after receiving a file from military police, which carried out an investigation into the matter.
The investigation began last summer after regular internal security checks raised concerns.
The case will be the first court martial under a new military justice structure which was set up last year.
Under the new structure the first dedicated military judge was appointed. Colonel Anthony McCourt, who worked for 27 years as a legal officer, was appointed by the President on the advice of the Government.
While he will decide on what, if any, sentence to hand down, a board of three members of the force will adjudicate on the verdict. The board is made up of at least one senior officer, but usually two, and one senior non-commissioner officer.
Accused members can apply for legal aid, which amounts to a solicitor and, depending on the severity of the case, a certificate of counsel (a barrister).
The accused also has the option of paying for his own legal representation or having a military officer represent him.