Lock 8 is just down the River from Boonesboro.
If you follow 27 thru Nicholasville toward Lancaster, cross over the river and go to the top of the hill. 1st road on the left. (Green Roofed log cabin on corner) follow this road back to the bottom of the hill and there will be two boat ramps on your right. The second is usually the better although it can be a bit tricky if the water has been up. (muddy)
Once your there, look at the river and turn right. Make about a 10 min run up to the lock (assuming you have an outboard over 90hp) if Not it may take you a little longer. IT ought to be hot in about 1.5 weeks maybe 2 depending on how much rain we get this week.
PS.. Don't tell everybody about this place there are enough boats up there as it is