You do not need to use the sea tiles with printed harbors from the old game, as enough tiles are provided with the Seafarer's Expansion. For the most part, follow the rules of Die Siedler. All apply except for the ones below. Shipbuilding A ship costs a unit of wool and unit of wood. Ships go along the borders like roads, but they can be moved.
Ships go on the border of two sea hexes, or on the coast between a land and sea.
When you've built a ship, you can place it next to a settlement or city, or next to another ship. You may not build ships at the end of a road, or build a road next to a ship without a nearby settlement. Take a look at Figures B-D on page 2 of the original rules for some examples. On each waterway, you can put only a single ship. Along the coast, you may only build a ship or a road-never both.