-57 would be slow vs an ANdrews 77 with a -180 or some such number. My local race a month ago had 6-8 boats with negitive ratings, the fastest monohull was Neptunes Carr at -66 or some such number, and DragonFly a custom 40' cat with a -120'ish rating, two other tri's at -75 or there abouts, A NM 53 @-9 from memory, and a id48 in the -20 range. We had 8 or so mono's with a 20 or faster ie lower rating. slowest was an etchals at 300 or there abouts. Funny thing is, a Baba 40 won there class, and had the fastest corrected time on the 24 mile long course for those faster than 180, and a US25 @ 257 won the 18 mile short course for those with a 180 and slower rating!
But as mentioned, compare the rating you have vs boats of equal size. If you have a 32'r, and a 180, compared to a melges 32 at 20 or there abouts, you're a slug! but compared to other 32'rs with ratings will typically be in the 90-150 range, so a bit on the slow side, but not to say you are a cruiser per say.
She drives me boat,
I drives me dinghy!