Answer :
Look at your given values, you have mass and velocity so the equation Ek=1/2(m)(v)^2 should be what you use.
It all depends where you are when you measure it.
If you're in the canoe or another floating boat, the canoe's kinetic energy is zero.
If you're a person standing on the riverbank watching the canoe float by, it's 46 joules.