Interesting! Very interesting. But I particularly like imagining the look on Snape's face, when he is saying this as he is processing just what he is saying when he is saying this.
This part is excellent as it is, though I am saying this focusing strictly on the little glimpses of snarry-to-be that are here.
I will never understand why everyone is confused with about the boat house. Of course there would be one -- where else would the Hogwarts boats be kept? C: