The Going Merry has a jib and a central steer rudder. The ship’s armaments consisted of four cannons, one in the bow pointing forward, one in the stern, and two pointing to either side. They were rarely used, as the Straw Hat Pirates usually preferred to run away or engage in hand to hand combat. After the Arlong Park Arc, the Going Merry gained three tangerine trees from Bell-mère’s grove, a memento of Nami’s home. As the series continued on, the ship received more and more damage and gained several metal patches to hold her together at places that could not be nailed back together: prominent examples are Merry’s figurehead and the mast, which was torn off several times. In the Skypiea arc, the body of the ship had wings and the sheep figurehead was dressed as a chicken.
In volume 11 of the manga, Oda presented various schematics and explanations of each part of the ship. These included everything from Merry’s figurehead to the kitchen.
Meeting room, Lounge, and Helm of the Going Merry
This is the single most important room in the entire ship. It serves as the meeting room, lounge, and helm for the entire crew. Here the crew can do a number of things. Since the kitchen is located here, they can enjoy a meal here made by Sanji. And because of its comfortable atmosphere, it is the perfect place where the crew can also hold meetings here and discuss what to do next.
The device for steering the ship is also located here. However, unlike regular ships that commonly have a steering wheel, the Going Merry does not have one. Instead it uses a “steering pole” with a sheep’s head like the one used for the ship’s figurehead. By tilting the pole left or right, the rudder at the stern will move in that direction.
Men’s room
The men’s room of the Going Merry is located below the deck of the ship right below the mast. It is quite large and untidy. This room is normally crowded due to the fact it is shared by Luffy, Zoro, Usopp, Chopper and Sanji to sleep. It is accessed through a hatch next to the mast. There are a total of five hammocks located here to sleep on. There is an emergency exit that connects to the women’s room in case something should happen.
Storage Room and Cannon Deck(aft)
A storage room and a cannon deck are located under the lounge of the Going Merry. This is where the crew keeps all their cargo such as beer barrels, water barrels, rations, and treasure boxes in storage. Any treasure that Nami cannot keep in the women’s quarters is kept here as well. The room also houses two cannons facing each side of the ship.
The bathroom and the women’s quarters can be accessed from here. Some towels can be found next to the bathroom’s entrance for when one finishes taking a bath. The hatch going down to the women’s quarters has a latch to keep out prying eyes.
The steering shaft that is used to steer the ship can also be seen located above this room.
Women’s Room
The women’s room of the Going Merry is located below deck under the storage and cannon deck. This is where Nami and Nico Robin (and for a time, Vivi) usually sleep. It was originally designed by Merry for Kaya’s use and thus its design reflects for whom it was originally meant. The room is accessed through a hatch that leads to the room above. This hatch has a lock for obvious reasons. There is an emergency exit that connects to the men’s room located here in case something happens. This hatch, however, is not normally used and is usually locked.
After the Arlong Park Arc, a bar was added here by a carpenter from Cocoyashi, Teru-san, from which people can drink.
Cannon Deck(fore) and Anchor Room
A cannon deck can be found below the front deck of the Going Merry. This also serves mainly as the room where the anchor is stored. Various weapons such as swords can be stored here. Giant oars and life preservers can also be found here and can be used when called for.
The cannon found here was used notably to fire at Laboon before the Going Merry rammed into him and broke her figurehead.
Bathroom
The bathroom of the Going Merry is located below deck next to where the rudder of the ship is located. It is accessed through a door leading to the storage room. This same door has curtains for privacy.
A shower, a bathtub, a sink, and a toilet can be found here. When Robin was frozen by Aokiji, the bathtub was used by Chopper and Usopp to thaw her out. The water used here is drawn up by a special machine located underneath the stairs on the top deck. There used to be two of these machines but Luffy broke one.
Care must be taken here after taking showers and such here. After cleaning themselves, the crew must make sure to thoroughly clean the place up with a rubber wiper found here in order to prevent the ship from being weakened by moisture.
Luffy’s Favorite Seat
The figurehead of the Going Merry is a sheep. This is where Luffy likes to sit most of the time while sailing. Why he likes to sit there with his inability to swim is a complete mystery. When this was temporarily broken upon impact with Laboon, Luffy expressed how mad he was and attacked the whale. The figurehead is also found on top of the ship’s “steering pole” in the main room. This design is also used for the figurehead of the Mini Merry II.
Throughout the series, the figurehead would sometimes show signs of expressions like a regular person. These have ranged from the comical to the sad.
Nami’s Mikan Trees
After the Arlong Park Arc, three orange trees from Bellemere’s grove were added to the top of the Going Merry. The fruits they bear are satsumas (Citrus unshui), but are usually translated as tangerine or oranges. Nami treats them with care, as they are mementos of Bellemere. They provide the crew with Vitamin C as well as decor for the ship.
Aside from Nami taking care of them, Sanji also protects these three trees from those who might otherwise harm them or steal the fruit (e.g. Luffy).
After Luffy and Usopp’s battle in Water 7, these trees were moved to the hotel room where the Straw Hats were. They were luckily found by the Galley-La shipwrights and moved to a safer location before the Aqua Laguna hit.
They, along with the rest of the Straw Hats’ belongings, now reside on the Thousand Sunny.