What was the distance for the winner or 2nd Waterline?
CREATE TABLE "1930_31_season_as_a_four_year_old" (
  "result" text,
  "race" text,
  "distance" text,
  "weight" real,
  "winner_or_2nd" text,
  "pos_n" text
);
SELECT "distance" FROM "1930_31_season_as_a_four_year_old" WHERE "winner_or_2nd"='waterline';