Once the list of the suggested routes has been displayed on your screen (just below the Voyage Planner Toolbox) you can expand any of them by simply clicking on the name of it. Notice the "Improve this Route" option.
Clicking on this option will enable you to edit the suggested route and let us know of it. While in the Edit Mode, the Waypoint markers will change and will also get more dense enabling you to alter any part of the route you think that could be improved.
To make any alterations to the suggested route, simply drag the desired point(s). You can always undo your last edit by clicking on the relevant icon that will appear after moving a point.
When you have performed the edits you wish, click on the "Save Route" button. Your suggestions will be evaluated by a MarineTraffic moderator and, if approved, will replace the suggested route.
If you are unsure about the edits you have made, click on the "Cancel Edit" button and you will exit the "Edit Mode" without making any changes.
Note that since all the displayed routes (as suggested by MarineTraffic) are based on actual past voyages, the results are realistic, but there may be room for improvements. We, therefore, invite you to suggest your edits for sub-optimal routes (the suggestion feature is available to all registered users). Such suggestions are more likely to become accepted and will result in replacing/improving the displayed routes in the future.
For the time being you can suggest improvements regarding existing Port-to-Port routes only. Since the Voyage Planner tool is still under development, more editing options will be added in the future.