Well, I don't know about the connection with beer. How about a site about fly fishing and a site about kayaks? That's a demographic that makes sense to interlink.
A path I'm taking is to peel off a demographic from a popular site and bring them over to the new and unrelated site. I won't interlink between the two sites in a general manner. But I will refer specific site visitors from highly specific pages on the old site to the new and different site. The idea is to filter site visitors to those most likely to click through and enjoy the other unrelated site that appeals to a demographic subgroup within the older site.
So I suppose something like that might work with your fly angler/beer drinking scenario; distill the beer drinker sub-group from the fly angler general group through specific linking but not through general linking.