To review: DIPPAM (Documenting Ireland: People, Parliament, and Migration) is an online virtual archive of documents and sources relating to the history of Ireland, and its migration experience from the late 18th to the 20th centuries. In this series I am focusing on one part of DIPPAM, the Irish Emigration Database (IED).
Beginning February 1756, information from newspapers about ships that sailed to North America is available to consult in the IED. The vast majority of entries are made up of transcriptions of short articles that focus on the journey of the ship. Information usually includes the name of the ship, port of embarkation, and where the ship is going to/port of arrival. The date of departure can be worked out from the date of the newspaper article. Lengthier articles usually mean that something out of the ordinary happened, such as the ship getting into difficulty at sea.
If you have been able to find the ship on which you Irish ancestor(s) arrived in North America, then you might be able to find more information from a simple name search for the ship. For example, this article discuses those about to embark on the Charles Kerr in 1838. The ship left from Limerick port and the majority of passenger were from County Clare.
The vast majority of passenger lists from before 1892 for those traveling to North America do not give a place of origin beyond, say, Ireland. Searching for the name of your ancestors ship in the IED is one tool that can be used to potentially solve this problem.