Workers are building the boat right on the beach using local materials, including plant fiber and sap to fill the space between the boards of the hull. The process is all by hand and absolutely extraordinary. The full article is here.
According to Indonesia Boat Building, “The making process of Phinisi Boat is some what unique, because it mixes technical skill with magical power….Every stage requires certain traditional ceremony. Before the boat is launched to the sea, maccera lopi (purify the ship) ceremony must be held, marked with the animal sacrifice. If the the boat weights less than 100 tons, the sacrifice is a goat. And if the weight is more than 100 ton, the sacrifice is a cow.”
A certain amount of magical power isn't limited to Indonesian boat building. Though it doesn't involve sacrificing an animal, in the U.S. mast stepping involves putting a coin under the mast for good luck. One can never be too careful when it comes to building a boat.
Thanks to Google Maps, you can see what it looks like to see these monster ships emerge from above.