Currently the ship pathing is pretty rudimentary, you can't change destination nor can you see which path a ship will take before committing and the path it takes can be wildly different due to the pathing implementation, presumably vanilla A*, you might need to tweak diagonal costs because it looks like they're pathing according to rectilinear grid rather than hex which should give some benefits for diagonal traversal which should relax the pathing a bit, make it seem more direct, this might be tricky due to the grid type but even easier is simply show the destination path preview as you move your mouse around, while it does dodge the problem i think that'll suffice. Many captains will be saved by this remediation and there will be services held yearly in great thank of your contribution to naval warfare.