From what I understand the order for the OPV's was delayed as the Roisin class has been deemed too small for current enviromental conditions in the North Atlantic , so these 2 new OPV's (with the option of a third) are 20% bigger than the P51 class (however a 130 meter lenght has been mentioned which would be closer to 70% bigger than the P51's)
The order for multi purpose platform vessels will now go to tender as the OPV order had to be finalised first , it is thought that at least 2 of these will also be ordered but timescale for delivery has yet to be decided , given the current fitness for service of some of the active vessels at least 1 of these could well be delivered before the OPV's.