Is this a respectable score (using GW 1.1a)?

[Zero Niner]

I'm in a Type VIIB, Oct 1939. 2nd patrol using GW 1.1a.
I've only 2 torpedos left, and have thus far on this patrol sunk 5 merchants (1 large cargo, 2 med cargo, 2 tramp steamers) for about 17k - 18k tons.
Using stock SH3 I've been able to get tonnages way above this. I'd like to know whether this is a decent score since GW damage model is different from stock.