Seaworthy describes a ship or boat that's safe and sturdy enough to handle the open ocean. A seaworthy vessel has a strong hull, working equipment, proper supplies, and everything else needed to survive storms, rough waves, and long voyages without sinking or breaking down.

Before any ship leaves port for a serious journey, inspectors check whether it's seaworthy. They examine the hull for cracks, test the engines and navigation equipment, verify that lifeboats and safety gear work properly, and confirm the crew has enough food and fresh water. A ship might look impressive tied to a dock, but that doesn't mean it's seaworthy. The real test is whether it can handle what the ocean throws at it.

The word can apply metaphorically to ideas or plans. If your teacher says your science project plan isn't quite seaworthy yet, she means it needs more work before it's ready to withstand challenges. Similarly, a business plan must be seaworthy before launching a company, meaning it's been thought through carefully enough to survive real-world problems.

The opposite of seaworthy is unseaworthy, a dangerous condition that can lead to disaster at sea.