To answer the original question you will need 2 radios to talk to ships and aircraft. Aviation VHF is AM (amplitude modulation) and Marine VHF is FM (frequency modulation). Chalk and cheese. There may be units around that have a single front end to the operator that "looks" like a single radio, but this is only the controller with the different flavours of radio mounted somewhere else.
The Technisonics is a good choice. It covers FM in UHF, VHF - HI and LO. Fully agile and frontend or PC programmable with all kinds of functions including cross band repeating. It is a small panel mounted (ARINC 610?) unit. Be aware that if you are in N America there is the TM550 and for outside NA the TFM556 with covers a different frequency band in VHF LO.