Tot,
The AH-1Z and the AH-64 are clearly superior to the Tiger and at least the 1Z and the older, but still superior AH-1W, can work in the maritime environment with no need to conduct major repairs after one short deployment.
The SH-60 is superior to the NH90, but very inferior to the V-22. Both can operate at sea with no serious degradation.
As to the Seasprite anyone had a better option.
Last time I checked Australia is surounded by water.
The Sultan