Flirting with children

The most maddening aspect of H's behavior is when one of our granddaughters is here.  I don't know what to do about it.  H and her "get cozy", touching arms and touching heads and leaning in to smile and laugh together.  Granddaughter likes the special attention but a 11 years old does not know about sex and men.  H is impulsive and thinks of himself as sexy and personable.  He is nearly 70 years old and flirts with anyone and everyone - it gets very embarassing to me when I am with him and he encrouches on his targets while I stand there with arms crossed. It is his personality.  His family is inappropriate in this way.  Young girls and uncles seem to share in potty words and curse words and it is soooo uncomfortable to me.  Anyway, with this granddaughter being such an impressionable age, I need to find some model of what my response should be for her safety.  H gets inappropriate and talking to him about it does not good...only fuels his anger at me.  What words can I say to granddaughter to teach her about men and flirting at such a young age to keep her safe.  Her mother is not a part of our lives anymore.