Not far from my mother's home place in Fermanagh, there is a Brockagh Brae, adjacent to Brockagh Bridge where the Swanlinbar road crosses the Sillees River. In the days (fifties) when we used to cycle all over, it was great fun going down; up, not so much.
There are very likely several more Brockaghs (at least another townland of the same name in Fermanagh).
As to the Glasgow-Belfast sailing time, Burns-Laird Line used to run overnight ferries from Lancefield Quay on the Broomielaw to Donegal Quay in the centre of Belfast, leaving at 9pm and arriving about 7am the next day. Journey times from Derry to Glasgow would be about the same.