Is it safe to make snarky comments about "good idea fairies" around Ireland? I'd think the local fae are not impressed.
Of all the three, the AC tend to be the ones that get "notions" the most, and always fall for the industrial PR and let themselves get talked into being first users/adopters, Dauphin, the CASA 225 MSA/MPA, the AW139s, tried for years to be the first user of the KC390.
In the case of the Eithne project, it goes back to the time when the Cobh Dockyard was actually part of one of the Dutch companies, they did all the model testing for the Irish navy (screwing up Deirdre something terrible, hence the running joke she was the first submarine of the NS), and they had got the Dutch navy onboard with helping the Eithne's development, with the Sea Lynx being the helicopter.
All grand, until the 80's being the 80's tensions over NI flared and the French arrived, promising all new capabilities with the Dauphin, the AC, loving the smoke the French were blowing up their arse, picked the Dauphin at which point the Dutch Navy pointed out that they didn't use it, and couldn't help anymore. Which would have been an issue to be worked on, but turns out the French shockingly had oversold how ready the new variant was, resulting in significant issues and delays, cost increases etc.
Queue finger pointing, yelling, DOD blaming both sides, long story short, why the NS was forbidden from having the 50's or 60's with helicopter capabilities.
Not sure where the suggestion for 4 of Eithne came from, off the top of my head, the "hope" was only 2 plus a "science" vessel variant, but the yard had terrible building practices and massive IR strains, it literally shut the day Eithne launched, she in fact had to be towed to the basin from memory.
The sad thing is, according to her designer, there was foreign interest in the design, think India at the time was looking at her as the basis of an OPV series, while the US Coastguard who worked with the NS/AC as they brought their own Dauphin variant into service reportedly considered her a better design than their own Famous class cutters. But with the yard in liquidation the ownership of the IP of the design was stuck in legal limbo so nothing ever happened.