WWJMU, The 16 HP Yanmar will push the boat at the rated hull speed, which is around 7 kts. If you subtract the current from hull speed that's how fast you will be going up river! The Yanmar is a great little motor and is used world wide in millions of boats, both commercial and private. The R-21 be it the Classic or the EC model is a great little boat and fun to operate but not suited for those who like speed. I'm just down the road from you in Kennewick, if you want to go out on the river and test one just give me a call and will put mine in the water and you can operate it. Bob