An Irish sailor who texted his girlfriend the location of his ship has been given a three-month jail sentence and discharged from the Republic of Ireland's Defence Forces.

Able Seaman Eoin Gray (24) had pleaded guilty to disclosing information without authority about the operation of state ships at sea between December 4 and 14, 2008.

The Dublin native had on several occasions contacted a colleague in the Fisheries Monitoring Centre about the status and location of his ship, the 'LE Orla'.

He wished to do so to see if he would be free to go home at the weekend and texted his girlfriend the information.

But yesterday, military judge Colonel Anthony McCourt told Gray he would no longer be trusted in the eyes of his superiors and had no future in the Naval Service.

Judge McCourt said the serious breach of discipline could have merited 12 months in prison and a discharge from the Defence Forces.

The sentence, imposed during a court martial hearing at McKee Barracks in Dublin, came in spite of pleas by Gray's counsel for a lenient sentence.

Ross Maguire pointed out that the charge of disclosing information had been one of five laid against his client.

Gray initially pleaded not guilty to all charges, but when he changed his plea for the charge of disclosure, the remaining four were dropped.

They included charges relating to the importation of cocaine, possession of cocaine and possession of eight counterfeit hair straighteners.

He argued that his client's decision to text his girlfriend about the location of his ship was serious, but it was a private matter and there was nothing sinister in his doing so.

Gray had been recommended to carry out a chefs course at the school of catering in October 2009 by the Naval Service and was due to qualify as a chef.

And a character reference from Paul Logan, of the Defence Forces catering service college, described him as an "excellent student" and "no trouble".

"I would ask the court to be as lenient as it can be as this is at the very low end of the type of offence that comes before the court," Mr Maguire said.

But Judge McCourt insisted the charge was serious and the Navy could not operate effectively if information was being disclosed.

Gray could not have been unaware of the sensitive nature of the information as he had two-and-a-half years of experience at sea, he argued.

"You have demonstrated that you cannot be trusted with information of a sensitive nature," Judge McCourt said.

The court noted Gray's age, the fact his two-year-old child was dependent on him and that this was his first offence.

Judge McCourt said there was no evidence that the information disclosed did adversely impact on naval operations, but the offence was serious enough to warrant a custodial sentence of three months and discharge from the force.

Gray was taken to the Curragh Military Prison yesterday, where he will serve out his sentence.

He was previously fined €50 and given a 15-day shore leave stop on May 28, 2007, after he took absence without leave for five hours.