Dads partner is an alcaholic should I say something?

[feltpaperchains]

That's it really, her drinking has got steadily worse over the past few years and now she drinks loads and is a pain in the arse when drunk.
Noone mentions it but Im worried about my dad, what should I do?

Well, you could tackle it head on. You may get no thanks, as it's likely they're both in denial about the problem. But it might make your dad stop and think a bit.

You could tell him you're worried about her from a health perspective but it depends how close you are (to him, and to her). If it's mainly the irritation of her drunken self, you may just need to avoid being where it is, if you see what I mean.