Seafarers' Record of Service and Norwegian Sea Service Book.
More information about this, is found here.
True copies
The Norwegian Embassy is only able to certify copies of Norwegian documents. If you need to certify an Irish passport or other document, please check out this link, https://www.statesavings.ie/help-support/help-articles/what-is-a-certified-copy-and-how-do-i-get-my-docum.
Some cases will need you to have a higher verification, an apostille. This is a service provided by Department of Foreign Affairs. You can find more information here, Authenticating documents - Department of Foreign Affairs (dfa.ie)