Not quite bug.
When you travel into fog, 90% of time your wetness level increases because of waves you crash into.
Wetness drains your sanity, so you don't have choice other than stopping and drying at the nearest island.
Since you can't control your boat while in fog, I would like to suggest adding wetness immunity from waves while traveling in the fog.
Steps to Reproduce
This issue has been closed either because it is not a bug or does not belong in the bug tracker.