For two years, the classic Voyager-type Saildrones—autonomous, unmanned sailing vessels up to 10 meters long—have been navigating the world’s oceans. Now, the US company Saildrone has introduced its latest product: the Spectre, measuring up to 52 meters long and weighing 250 tons. Like its smaller sister, it is an “autonomously navigating robot ship” under sail or, more recently, exclusively under motor power. SeaHelp explains what leisure skippers should look out for if they happen to cross paths with such a Saildrone.
Since 2024, the so-called Voyager type Saildrones have been plowing through the world’s seas in search of data. Strictly speaking, the US manufacturer emphasizes that these small vessels are not sailing boats in the traditional sense, but “autonomously navigating robot ships” under sail.
All Saildrones have one thing in common: There are no humans on board. This can lead to problems, because where there are no people on board a vessel, they do not always behave like “normal” ships steered by humans.
First of all: The small, “classic” Saildrones have a length of approx. 10 meters and move at a speed of about 5 knots (9.3 km/h)—powered only by the wind and supported by a small electric motor designed to ensure technical autonomy for about 100 days. The boats are controlled via satellite from a location that could theoretically be anywhere in the world, combined with AI.
Previously, Saildrones were 10 meters long, designed to collect environmental data, and unarmed
These small robot ships are equipped with radar, AIS, and camera/IR systems, and according to the company, are intended for measuring specific environmental values. Important to know: These versions are “predominantly” unarmed and are already in use worldwide.
Specifically, these models—each equipped with a rigid wing sail (a sail that works like an airplane wing)—have been “sailing” across the Pacific since 2024, where they are used for research purposes on behalf of the US Navy. They have also been deployed for two years in the Caribbean—monitoring migration and tracking specific vessels—as well as in the Arctic and Antarctic.
However, local skippers could also unexpectedly come into contact with these high-tech boats, as they are now being used in the North and Baltic Seas, for example, during NATO tests. Specifically, in 2025, several Saildrones were operating in the Baltic region.
The new Spectre model is 50-52 m long and is clearly intended for military purposes
Compared to the newly introduced model named Spectre, the previous Voyager boats almost look like toys. While the US company for autonomous unmanned surface vehicles (USVs), Saildrone, previously only developed self-driving boats up to a maximum length of 10 meters “for ocean research and obtaining weather data,” Spectre is now clearly designed for military use.
In plain language: These ships are intended to hunt submarines, provide long-range surveillance of specific maritime areas, and carry weapon systems (missiles, etc.).
And: unlike the Voyager models, the Spectre ships of the new version introduced in 2026 are more than five times as long. Specifically, their length is reported (e.g., by heise online) as “50-52 meters,” with a weight of “about 250 tons,” and they are capable of speeds up to “30 knots” (55.5 km/h).
The new Saildrone Spectre can travel autonomously for nearly 15,000 kilometers
The range of the new USVs is said to be an incredible 3,000 nautical miles at high speed (more than 5,550 kilometers); at slower speeds, it can even reach up to 8,000 nautical miles (more than 14,800 kilometers). The payload capacity is approximately 25 tons, according to further reports.
For submarine hunting, the boats could be equipped with sonar, and like their smaller Voyager counterparts, they are expected to carry radar and ISR (Intelligence, Surveillance, and Reconnaissance) systems. They may even serve as launch platforms for missiles such as the Mk70 or JAGM, as reported by The War Zone.
One thing is certain: Two variants are soon to be sent out for testing. The Spectre “Silent Endurance” is equipped with a wing sail, while the “Stealth Strike” model will run exclusively on engine power—and will therefore be faster than its sailing counterpart.
Unlikely, but not impossible: A sudden encounter between leisure boats and Saildrones at sea
Although it is highly unlikely that a leisure skipper will encounter a Saildrone at sea, it is not entirely impossible. Therefore, one should—at least mentally—rehearse this scenario and discuss it with the crew. The most important rule for an encounter at sea is: Treat it as a vessel restricted in her ability to maneuver, as they operate autonomously and do not “react” like a human.
But first, the question arises: How do you recognize a Saildrone at sea? Distinguishing features can include: a high rigid wing (somewhat like a vertical airplane wing), no crew deck, and they are either very small (10 m / Voyager) or very large (50-52 m / Spectre). Furthermore, these self-navigating ships are supposed to transmit an AIS signal, which should be easily receivable upon approach.
In AIS, Saildrones usually appear as a normal AIS target, not as a “special drone symbol.” Typical indicators might include: Name: e.g., SAILDRONE, SAILDRONE VOYAGER, potentially combined with a number; Type: often Unspecified / Other / Special Craft / Sailing vessel (depending on AIS configuration).
The speed (at least for Voyager models) is usually slow, writes Saildrone, meaning “up to about 5 knots” / 9.3 km/h. It should be assumed that the Saildrone (Voyager) uses radar, cameras, and “maritime surveillance sensors” in addition to AIS, according to the manufacturer.
“Worst Case” Example Scenario:
Assume a leisure crew is sailing at 6 knots (approx. 11 km/h) and suddenly finds itself on a collision course with a Saildrone approaching from starboard ahead at 4–5 knots (7.4–9.3 km/h). The point of theoretical intersection is under 0.5 nm (less than a kilometer), and the event is expected in 10–20 minutes. How should the skipper behave correctly in this situation?
Step 1: Do not insist on “Right of Way.”
Even though the COLREGs (International Regulations for Preventing Collisions at Sea) formally apply—autonomous ships raise practical, not yet fully answered questions of interpretation in this situation: Where are the boundaries between COLREGs and fully autonomous navigation?
Step 2: Take CPA/TCPA seriously.
When dealing with an unmanned target, one should generally navigate more conservatively than when encountering a fishing boat or another sailor. This also applies to encounters with USVs. For a CPA (Closest Point of Approach) under 0.5 nm, you should actively move to avoid it; for a CPA under 0.2 nm: act immediately and decisively.
Step 3: Maneuver early and clearly.
This means: Do not just “fidget” with a few degrees of course change. Better: Change course by 20–40°, or significantly reduce speed, then check if the CPA is clearly increasing again.
Step 4: Try VHF, but do not rely on it.
On Channel 16 or the local traffic channel, you can call out: “Unmanned vessel / Saildrone (Name if on AIS), this is sailing yacht…”. However: Although Saildrones should always be (remotely) steered and monitored, there is no guarantee that someone will answer.
Step 5: Maintain distance.
Practically recommended: At least 0.5 nm distance, better 1 nm (if space permits); never cross closely behind the stern or directly in front of the bow; at night or in heavy seas, the distance should be increased accordingly.
According to Saildrone, the danger is “not the crossing itself, but crossing closely with the assumption that the drone will react like a human.” One is well-advised to treat a Saildrone “like a highly unpredictable, slow-moving work vessel: avoid it early, clearly, and generously.”
