Google Yachats tide conditions 2015. It's also worth noting that other weather conditions such as swell, storm etc will have an effect on your experience so watch the weather forecast for the area.
There is a fabulous app available in Google Play or iTunes for smart phones called "Tides Near Me" that provides tide information.
You can google "Tide Tables Yachats" and get the closest location to Devil's Churn... or, for most Oregon tides, google
"Tide Tables HMSC" -- this is the Hatfield Marine Science Center at Newport and their tables are for the South Beach of Newport which is a little bit later than Devil's Churn, but not a lot.
Get quick answers from Devil's Churn staff and past visitors.