Any Ranger Tug (or Cutwater) should be able able to easily run Deception Pass with 4 knots or less of current. This widens the window of opportunity to cross.
We run Deception pass a lot each season. It's our primary course to get to the San Juan Islands.
Also note, tides and currents are different. Do not assume that high tide is slack water. At Deception Pass, they are not the same. Slack occurs before or after high or low tide (depending on which way you're headed).
Start at the 5:20 timestamp in this video for an illustration of how to read Deception Pass.
https://youtu.be/OShrTz0sYok?t=322
This video is pretty good as well, as it compares Deception Pass vs Admiralty Inlet, vs the Swinomish Channel.
https://youtu.be/fpVO9Hy71pY
I will always run Deception Pass when it's 4 knots or less, in either direction, without hesitation. When It goes above 4 knots, it changes... and fast. I have gone through Deception with 7 knots with the current, and 6.5 knots against the current. It's way different at those speeds. 4 knots or less is easy and the Admiral on board approves.
🙂
Another note.. and I should probably do a video on this... Once you cross Deception heading North... don't run to Thatcher Pass... Run over to Lopez Pass. It's a shorter crossing over Rosaro, you will avoid running near Belle Rock (it's always rough/bumpy around there), and you'll avoid all the ferry traffic that runs through Thatcher pass. Lopez Pass also gets you into protected water quicker than running up to Thatcher.