6 min read
Sea drone, water drone and saildrone: three terms that are often mixed up, but mean slightly different things. They all fall under the USV (unmanned surface vessel). In this article we explain the differences and help you choose which type suits which task.
The three terms in short
All three are unmanned vessels that travel across the water surface. The difference is in the emphasis: where they sail and how they're propelled.
- Water drone: the umbrella term for any unmanned vessel, regardless of the water or propulsion.
- Sea drone: a water drone built specifically for the open sea, resistant to waves, current and salt.
- Saildrone: an unmanned vessel propelled by wind (a sail) and solar energy, made for long-duration missions.
Water drone: the umbrella term
Water drone is the broadest collective term. It only says that a vessel sails unmanned over water, whether that's a lake, a river, a harbour or the sea. A water drone for inland water is often built lighter and doesn't need to handle high waves. So the term says nothing about the build or the deployment area: for that you use a more specific term such as sea drone.
Sea drone: built for the open sea
A sea drone is a water drone that has to endure the open sea. Think of the North Sea: waves, current, salt and changing weather. That places heavier demands on the hull, the sensors and above all the autonomy. A sea drone must reliably detect obstacles and other shipping traffic and choose a safe course, even when conditions are rough. Deployment areas include search & rescue, inspection & survey, workboat tasks and defence.
Saildrone: sailing and solar powered
A saildrone stands out through its propulsion: instead of a motor it uses wind and sun. As a result such a vessel can stay at sea for weeks to months without refuelling, ideal for collecting ocean data over long distances for a long time. The downside is speed and agility: a saildrone moves slowly and is less suited to tasks where you need to be on the scene quickly or manoeuvre precisely, such as a rescue operation.
Which do you choose for which task?
- Inland water, harbour or survey on calm water: a lighter water drone is enough.
- Open sea with fast response (SAR, inspection, workboat, surveillance): a sea drone that can handle waves and current.
- Long-duration ocean measurements over large distances: a saildrone on wind and sun.
The difference isn't in the hull, it's in the brain
Whether you use a water drone, sea drone or saildrone: the intelligence sits in the autonomy system on board. It detects obstacles, computes a course and advises the operator. Dutch USV Technologies develops that brain and connects it to existing boats, so every vessel becomes an affordable, autonomous sea drone. With Level 2 autonomy the operator always keeps the final decision: autonomous where it can, with a human in the loop where it must.