The crew of the LE Eithne have rescued a further 647 migrants - among them eight children - from two wooden barges in the Mediterranean.
In another hectic day for the crew, they transferred 593 migrants rescued on Sunday to a larger British naval vessel in the early hours of yesterday morning.
A few hours later, at around 8am Irish time, the LE Eithne began another operation when it came to the aid of 330 migrants who were packed on board an open-decked wooden barge, around 50 miles off the coast of Libya.
That operation finished at 10.30am but immediately after this, the crew was directed by Italian authorities to another stricken barge that was in the area.
Another 317 migrants were on the second vessel. They were transferred to the LE Eithne bringing to 647 the number of migrants on board - 544 men, 95 women and eight children.
Meanwhile, Ireland will replace that LE Eithne on refugee rescue duties in the Mediterranean with the LE Niamh in just over two weeks' time.
Defence Minister Simon Coveney hailed LE Eithne's 69-strong crew as "true Irish heroes" for their role in helping save the lives of over 3,000 migrants in the space of two months.
Now, the Government will extend Ireland's humanitarian mission to support the Italian authorities - and will consider deploying a third ship if necessary in September.
"Before the end of July the LE Eithne will return to Ireland and a new ship, more than likely the LE Niamh, will go out and continue the good work," Mr Coveney told the Irish Independent.
"What the Naval Service has been doing over the last couple of weeks has been truly heroic stuff.
"They have been doing Ireland proud.
"But that is what they are trained for, it is what they are expected to do and it is what they expect of themselves," he added.
LE Eithne departed Cork on May 16 for an eight-week search and rescue mission off southern Italy.