A Log Pose is a compass-like navigational device, a necessity for traveling the Grand Line.
The standard Log Pose is a bracelet with a glass orb sitting on top, and a needle floating inside the middle of that orb suspended from the top by a thin piece of wire.
Normal compasses do not work in the Grand Line due to the special magnetic waves created from each island. The Log Pose functions by recording the magnetic waves of one island after another in the Grand Line, and the needle points to that island so the user can travel there. Once on an island for the required amount of time, the Log Pose resets and locks on to the next source of magnetism, causing the needle to start pointing toward the next island. The time it takes to lock onto the magnetic waves of the next island varies from island to island, it could require hours, days, or even years.
The standard Log Pose is not suitable for sailing in the New World, due to the fact that some islands change or even completely hide their magnetic fields at random, which may leave a crew stranded if they rely on a Log Pose with only a single needle. To navigate safely through the New World, a crew needs to have a Log Pose with three needles. Each needle records the magnetism of one of three different islands simultaneously, as opposed to the Paradise Log Pose, which only records the magnetic waves of one island at a time. The stability of the needle reflects the stability of the island's magnetic field; if the needle is displaying erratic movement, it means that the island's magnetism is unstable. There are no guarantees, but as a rule of thumb, this likely means that there is something dangerous on the island causing the disturbance in its magnetic field, as changes in magnetism can be caused by abnormalities on the islands in the New World.
It is possible to navigate between islands following the change in direction or sensitivity of each needle as opposed to choosing to follow only one, as explained by Charlotte Pudding's map of Totto Land.
Larger mounted versions of a Log Pose can be found on ships such as the Thousand Sunny, as they have the Paradise version on its helm. Upon reaching the New World, they updated the large Log Pose to the appropriate version.
Log Pose Owners
Many characters throughout the story own a Log Pose, as it is necessary to travel the Grand Line:
- Mr. 9 (Lost, found by Luffy taken by Nami, destroyed)
- Crocus (given to Nami)
- Portgas D. Ace (confiscated upon imprisonment)
- Galdino (discarded or lost)
- Golden Lion Pirates
Translation and Dub Issues
The 4Kids-dubbed anime (as well as video games) renamed the Log Pose and Eternal Pose to Grand Compass and Eternal Compass, respectively. While this renaming was kept by the Funimation-dubbed anime's initial TV cut, both the uncut Funimation anime and the Viz Manga use the original terms.
In addition, to fit story changes that truncated the Reverse Mountain Arc to remove Laboon and Crocus, and completely eliminated the Little Garden Arc, the 4Kids anime extensively rewrote the context behind the Poses the Straw Hat Pirates acquire during the Arabasta Saga:
- The crew's first "Grand Compass" (originally taken from Mr. 9) is depicted as an item that Yasopp deliberately left Usopp. Several of the Straw Hats recognize it on sight, and its workings are explained by Sanji, relaying experience from Zeff.
- The quickly-broken "Eternal Compass" that Robin gives the crew at Whisky Peak is said to lead directly to Arabasta, rather than Nanimonai Island.
- The compass ultimately used to reach Arabasta (originally taken from Mr. 3's base on Little Garden) is depicted as a spare that Igaram gave to Vivi, which was "forgotten" until Luffy broke Robin's.