The real captains logs are the voice notes you make to yourself on the toilet.

Not sure, if you'd actually want to use this, but I found this: https://bmortella.github.io/captains-log/

And of course, there's also the matching Linux desktop environment to complement it: https://lcarsde.github.io/

I'm actively working on building something for this. In the interim, most phones have something akin to a voice recorder with transcriptions.

I call my journal captain's log