Frankly, I have heard that as the reason that Ham was not cursed, but have never understood it.
God establishes a covenant with the sons of Noah not to destroy them again with a flood.
Why could He not have then cursed Ham to be a servant of servants if he were in fact guilty of some crime?
The blessing had nothing to do with the cursing.
That is only used by the sons of Japheth trying to justify their enslaving all the sons of Ham (not just Canaan)
No, this was Noah spouting off, and it had no effect whatsoever, because what God blesses, man cannot curse (well, cannot curse with any effect). Moreover, there is no indication whatsoever that this curse extended BEYOND Ham's sons---even it it did "take," and moreover, no evidence whatsoever that it was in anyway associated with black skin. It was, pure and simple, the concoction of racist minds.