Actually, No you don't Need A Boat...
As a matter of fact I do quite a lot of my bowfishing from shore. A lot of Lake St. Clair where I fish in Michigan, you can wade a lot of the bays. I also fish in the Saginaw bay area and wading the marshes, creeks and bays is my choice of fishing. There are also a lot of creeks and canals that walking is the only way to do it. Since most of the time you're hiking through the woods to get to a certain river or creek. I also have an area about 10 minutes from my house where I drive behind a industrial complex, park my truck and walk a small creek that comes off of the spillway, that is just loaded with carp. There's even a lot of time when I am fishing from a boat that I'll get out and wade the shallows. Except for night fishing where I'm fishing for gar or bowfin, is the only time I stay in the boat.