When you log in to Old Weather, you will not be directed by default to the last ship you worked on.
If you want to keep working on a particular ship, bookmark/favorite your ship's home page.
Open Old Weather from the bookmark and click Transcribe logs. The log in page will then open.
After you log in, you will be taken directly to your chosen ship's log.
You may choose to bookmark My Old Weather (http://www.oldweather.org/profile
Log in if necessary and when the page opens look for LAST ACTIVE VESSEL
at the top right.
Click the name of your ship, which will open its homepage, click Transcribe logs and you're away.