I have current Canadian Hydrographic Service
charts of areas of Newfoundland that specifically say "No Datum." These are
charts that were last surveyed 150 or so years ago. So Ireland is not alone.
As to entering unfamiliar ports at night, it all depends. What does the harbor and approach look like on the chart? How confident am I in the accuracy of the chart? How is the entrance described in cruising guides or pilots? How familiar am I with the type of setting (e.g rocky emergent coast, barrier island coast, estuarine rivers, etc...), if not that particular harbor? Are the aids to navigation lighted or not? (Are there even any aids to navigation at all?) What are the weather and sea conditions? What's the condition of my boat? Who do I have for crew? What's the condition of the crew? What other alternatives are there?
Tim