If you want to get into Maritime IT, I'd suggest downloading copies of the installation regulations/standards and becoming familiar with the equipment used on the majority of the world's shipping. The main regulatory bodies involved are:
- Lloyd's Register (LR)
- Bureau Veritas (BV)
- Det Norske Veritas (DNV)
- American Bureau of Shipping (ABS)
- Registro Italiano Navale (RINA)
Although there are a host of others, these are the main ones. Do a web search for the standards of each of these and get familiar with them.
Remember that Maritime IT is not restricted to just a few office computers and servers (although there will certainly be that) - you must come up to speed with digital radar, GPS, radio and satellite comms and protocols especially AIS and GMDSS.
If you have experience with amateur radio, that would help. Search the web sites of the main navigation equipment suppliers like Thales, Raytheon, etc.. and good luck.