We do Colvos a lot and will be going south in a couple of weekends. My experience is if you go on a flood the current will be mostly negligible for the most part. If you go on an ebb, you can hug the Vashon side and find less current. Going north on the ebb can give you a nice push, maybe 2 knots at times.
The five stages of life: Sailboats, Motorboats, Motor Homes, Nursing Home, Funeral Home.