Good day for an Irish interest post - Happy St. Patrick's Day!
That sounds like a great cruise, you've got the right boat for the job, is she calling to see Her Maker at Cushendall? The Irish CG will be happy to record a TR for you but won't (officially) take any action if you fail to report in. Unofficially, they're not in the busiest shipping area in the world and will probably keep a weather eye on you if things get sporty. I think you'll be dealing with the same Control Centre for the Southern leg of the trip.
A Secret Revealed: Only visitors actually call it Eire! Despite plastering it all over our Passports, Stamps and Coinage, we sneakily call home Ireland (when we're at home), Republic of Ireland (when we're not) or The South (when we're in The North). oh, and Eireann (when we're talking "as Gaelige").
There's a really good pub in K.Quay (up street on right, name anyone?) that does a wicked seafood platter and serves A1 Guinness - not to be missed.
Best of Luck in the Eireish Sea!