A river isn't big water in almost any example. "Big water" has a larger surface area that makes it conducive for the wind to create waves. For example, I fish Lake Sakakawea quite a bit, and it can have 2 or 3 foot rollers on it pretty easily with a west wind. If you're 20 or 30 miles from the boat dock in a 20 mph wind, that's where a fiberglass boat will shine and an aluminum boat will beat you up. In a river, whether it's the detroit, missouri, mississippi, or whatever, it's pretty rare to be fishing in wave conditions like that. River's aren't wide enough and they change directions to many times for wind to really be able to pick up steam and create waves. I've fished the Missouri in the spring in 25 mph winds, there wasn't a wave on the water at all. Sakakawea in those same conditions would've had white caps accross the whole lake. Aluminum boat would've been limited to 10-15 mph and it would still beat you up. I could drive 40 in my fiberglass and its a much smoother ride.