Isherwood managed to get the frigate 's engines lit off ; .
The previous night secessionists had sunk light boats in the channel between Craney Island and Sewell 's Point , blocking Merrimack .
Isherwood managed to get the frigate 's engines lit off ; but the previous night secessionists had sunk light boats in the channel between Craney Island and Sewell 's Point , blocking Merrimack .