"Shipwreck Saturday" is an episode following the episode "Chicken Pox." It begins sort of the same way the last episode ended. In this episode, they make a new boat and the canoe hits it and his boat sinks in the water, causing him to cry.
The episode begins with April bouncing her basketball in the kitchen, and pretending to shoot a basket, but Big Bill holds the ball still. He tells her that she needs to wait until they get to the park before she plays basketball, and she agrees. Bobby brings out a kite that's going to fly higher than all of the others at the park. Little Bill has a boat that he and his father made for the park trip, and shows Bobby that his boat is flying. April notes that boats can't fly, but can float on water. Bobby says that they only do if they were made right, and asks Little Bill how the boat will float. Big Bill insists that it looks strong to him, and Little Bill looks it over and asks him the story about a big whale and a boat. That story is Moby Dick, and it's one of Big Bill's favorite books. Little Bill also likes that book, and that's what he's going to name his boat. It's a good name, but the boat still needs one more thing. Big Bill holds out his two hands and cups them. Little Bill chooses one, and sees a captain figure for his boat. Big Bill says that if the boat will sail, it needs a captain. Little Bill gives him a hug and thanks him. Little Bill glues the captain onto his boat, and now it's perfect. He then asks if they can leave, and everyone is ready to head out.
The family arrives at the park to have some fun. There are a lot of people there today, and Big Bill prepares the picnic, and starts to cook some hamburgers on the grill. Little Bill asks him to come sail his boat with him, but he must get the hamburgers ready, and then he'll come out and help him. Little Bill agrees and heads out to sail the boat, but trips on a rock, and it goes flying through the air. Little Bill is able to catch it before it hits the ground, and his father says that that was a very good catch.
Little Bill walks down the park and sees Kiku and her grandmother, Ms. Natsuko, sitting at a table and playing with paper. Little Bill greets them and asks them what they are doing. Kiku says that it's origami, which is when a person takes paper and folds it into different shapes. Little Bill sees some that they've made, such as a shell, a dog, a flower, and a castle. He says that the castle is where King Origami lives. Ms. Natsuko notes that it was supposed to be a rabbit, but she admits that it can be a castle. Little Bill shows them the boat that he made, and Kiku asks if he made it all by himself. Little Bill says that Big Bill helped him, and he's about to go sail it. Little Bill asks Kiku if he wants to come sail it with him. Ms. Natsuko agrees, and her granddaughter goes with Little Bill.
The two walk down to the lake and put the boat in there, which really does float. Big Bill notes that it's looking very good. The wind picks up, making the boat sail along the lake's coast. The two run after it and have fun, and Kiku notes that it sails quite fast. Bobby and April cheer their little brother on as they fly their kite and play basketball. Little Bill is happy and notes that the boat is sailing. He and Kiku pretend to sail on the Moby Dick, see a whale pop out of the water, and say hello to him.
Suddenly, Kiku gasps to Little Bill that something is wrong. Little Bill sees a man in a canoe coming right at the Moby Dick, and he and Kiku shout out to him to watch out. However, he's wearing headphones, so he can't hear them. The kids continue to yell, and Big Bill also starts to try and get the man's attention. However, he still isn't able to hear them, and rows right over the Moby Dick. It breaks into pieces and the captain sinks underwater. Little Bill starts to cry over his damaged boat, and Kiku suggests to try and fix it. Little Bill continues to cry, and Big Bill tells him that he's sorry and knows that he worked hard on that boat, and hugs him as he cries. Big Bill hopes he'll feel better soon. Still crying, Little Bill wants to go home now, but Big Bill asks about their cookout picnic, noting that April is still playing basketball, and Bobby is still flying his kite. Little Bill is still sad about his destroyed boat, and Big Bill suggests fixing it, but it got crushed. Big Bill tells him to find something else to do, that if he makes up his mind, then he'll have fun, and that they'll all look at that shipwreck.
They walk down to the wreckage, and Kiku notes that the boat can't sail anymore. Big Bill also notes that there aren't enough pieces to fix it. Little Bill looks up at something, and Big Bill asks him what he's looking at. Little Bill asks his father if he knows how to make a kite, and the three take two sticks and the ruined boat back to Ms. Natsuko. They take the sail that was on the Moby Dick, and change it into a kite. Kiku even puts her necktie on the kite to help it fly.
When the kite is done, Little Bill brings the kite over to where his big brother is flying his. Bobby thinks the kite looks really cool, and Little Bill tells him that it's a boat kite, and now it can fly. Little Bill and Kiku let it go, and it flies just as high as Bobby's. Alice the Great and Brenda note that the kite is nicely made, and the episode ends with Kiku, Little Bill, Bobby, and Big Bill flying their kites in the air.
While Kiku and Little Bill are making the Moby Kite, Kiku contributes her necktie to be used for the kite's tail, but when we see them start to fly the kite, Kiku is wearing it again, yet the kite still has the tail. How is it in two places at once?