The Bible speaks of Noah being perfect or blameless.

But Noah found grace in the eyes of the LORD. This is the genealogy of Noah. Noah was a just man, perfect in his generations. Noah walked with God (Gen 6:8-9).

In what sense was Noah perfect or blameless? He certainly was not perfect in the sense that we use the word today—without sin. Perfect, in this case, has the idea of being upright, living in a close relationship with God. This describes the general character of Noah's life. Old Testament authority Victor Hamilton writes:

The word blameless means free from defect, as may be observed in the many passages describing the unblemished animal presented to God (Exd 12:5; Lev 1:3, 10; Lev 3:1, 6, etc.)...of course, Noah was not free from defect. He was tamim, but not sinless. Perhaps a word like wholesome or sound or candid would be appropriate when applying this word to people (see Gen 17:1; Deu 18:13; Psa 15:2; Psa 18:24; 2Sa 22:24; Pro 11:5; Job 12:4) (Victor Hamilton, Gen 1-17, Eerdmans, 1990, p. 277).

Though Noah lived a wholesome life, he was not without sin. Scripture records the episode of his drunkenness. The Bible, therefore gives a complete picture of Noah's life—one that was characterized by wholesomeness but one which also had its sinful moments. This is why Noah, like the rest of us, had to find grace in the eyes of the LORD.