Just because a current is flowing at x knots, a boat that will only do x knots hull speed is pretty much stuck in place. Doesn't matter how fast the current is flowing, what matters is how fast the boat is moving against the water. In a current, unless the boat will go faster than the current you'll go bacwards. Adding a bunch of horspower only digs a deeper hole without much, if any gain in forward speed. Boats just don't exceed their hull speed by much unless you get them up on a plane. If there is wind and wave action, a bigger engine can have a beneficial effect but that's seldom a problem in the PNW.

If you have a 6 knot boat in a 9 knot current, all the horsepower in the world isn't going to do you any good.