Hi Vlad1980!
I have found that M101 (Pinwheel galaxy) was one of the most difficult galaxies I've detected so far. I'm from central NJ too and the light pollution makes low surface brightness galaxies extremely difficult to see. 
I was just barely able to detect M101 as a wisp of haze with averted vision on a night of good transparency. And, I'm using 12" of aperature.
I think you actually have a better shot at seeing M51 as it has a higher surface brightness.
M101 is above (North) Alkaid. It makes an almost equilateral triangle with Alkaid and Mizar/Alcor such that M101 is at the tip of the triangle above (North) the dipper's handle.
If you look at Alkaid then look South West by about 10 deg., the next bright star you'll come across is Cor Caroli in Canes Venatici. M51 lies roughly on this line about 1/3 of the way from Alkaid to Cor Caroli. Incidentally, M63 (Sunflower galaxy) also lies roughly on this line about 2/3 of the way from Alkaid to Cor Caroli. M63 is a tough one as well, but not as tough as M101, IMO. 
M94 is an easier galaxy to see and it lies North of the line adjoining Cor Caroli and Chara. They make a wide obtuse triangle with M94 at the wide tip.
Last year, while searching this area with my 5" reflector, M94 was the only galaxy I could see. I was not able to find the others (M63, M51, and M101) until this year when I used the 12" reflector.