The WSDOT does a great job posting ferry schedules and making them available for cell phones. For some reason tho, the exact quotas for cars on each sailing are not online — you can get them in person at the ferry docks but no online presence. They are willing to email them to you tho, so here they are for Lopez this summer:
|_. Sailing |_. 6/22- 7/6 |_. 7/7 – 7/27 |_. 7/27 – 9/27 |
There are separate quotas for overheight vehicles, let me know if you need those.