The GMDSS marine radio guidelines brochure for small craft users in Europe (pdf) provides useful information about the Global Maritime Distress and Safety System.  This system became fully operational on 1 Feburary 1999. 

This brochure is also available from the Coast Guard as follows:
Coast Guard Administration
Department of Transport
Leeson Lane
Dublin 2.
Ph:   +353 1 678 3427
Fax:  +353 1 678 3459
Email: admin@irishcoastguard.ie