Possible Clues:

• Their sporting activity will involve them in a row
• A sermon about rowers
• They propel a boat manually
• They propel boats manually
• Crew - some ran amok
• Sign either side of a river ultimately deters those on it?
• They work with sweeps
• Henley participants
• Galley workers
• There's bound to be a row if this lot is involved, as these types always make their move on Liffey