Straight rowing from the dam downstream will put you at Betty's in about 2.5 hours! During 1 generator make sure to catch it on the fall and you should have a good float. This of course will get you half way downstream rather quickly. This is a float to where you want, fish, float, fish style river. It's becoming more and more combat like on that river and it kind of forces you to fish this way. I'd reccomend picking another river! I mean that seriosly..Super crowded.
As far as watercraft any will do even during generation (1 generator). It's a cake of a river.