In "The Inchcape Rock" by Robert Southey, how does the character of Sir Ralph the Rover compare to that of the abbot?

In the poem, the Abbot of Aberbrothok has attached a bell to a buoy to warn sailors of the perilous Inchcape Rock. When mariners hear the bell, they know that they have the abbot to thank for their lives.

In the meantime, Sir Ralph the Rover is a pirate who appears to be completely unlike the abbot. The poem tells us that when Sir Ralph feels the 'cheering power of spring,' it makes him sing and whistle. However, his heart is 'mirthful to excess' and his mirth is 'wickedness.' The pirate is happy when he can commit wicked acts; the spring inspires him not to good works but to acts of sabotage.

Sir Ralph commands his men to row him over to the Inchcape Rock so that he can cut the bell from the 'Inchcape Float.' He is gleeful as he performs this dastardly act, announcing that 'The next who comes to the Rock, / Won’t bless the Abbot of Aberbrothok.' Sir Ralph is unrepentant as he sails away to plunder among the high seas. Soon after he has 'grown rich with plunder’d store,' he then 'steers his course for Scotland’s shore.'

However, because of the stormy sea, Sir Ralph and his men cannot tell where the shore is. Sir Ralph desperately wishes that he could hear the Inchcape Bell. His wish is not answered, of course, as he was the one who has cut the bell from its buoy. The irony is complete when Sir Ralph's vessel dashes itself against the Inchcape Rock; as the ship sinks, Sir Ralph tears his hair and curses in despair. So, while the abbot's chief aim in life appears to be to bring comfort and hope to others, Sir Ralph lived to cause others pain. As a pirate, he excelled in the arts of plunder and mayhem; his actions brought others woe, while the abbot's unselfish actions saved many lives.