Babcock Marine received the contract for the two ships in 2010 in a deal worth nearly $126.4 million, exclusive of weapons systems, which are worth an additional $9.95 million.
Both sums quoted last week by Ireland's Minister for Justice, Equality & Defense Alan Shatter are exclusive of Value Added Tax.
The first ship ordered will be delivered to Ireland in early 2014. The second ship will be delivered by Babcock Marine the following year. Both are replacements for Naval Service vessels being withdrawn from service
Ireland said a traditional keel laying ceremony was held at Babcock Marine's Appledore Shipbuilding Yard in Devon. Senior Irish officials attended the event.
Additional details on the two vessels being built for Ireland were not disclosed.
Ireland said payment for the patrol boats are scheduled to be made over a period of eight years, with funds coming from within annual defense appropriations.