
Technical Specifications
Live Tracking
Most time stopped at Rouge River — 23 h across 5 stays.
Derived from the AIS track — runs of near-zero speed (anchored, moored or drifting) snapped to the nearest port. Builds up as we observe the vessel.
Intelligence
AIS-derived from our live feed.
Compliance
On 20 December 2025, the bulk carrier "ROBERT S. PIERSON", reported a fire in an accommodation's locker in Keweenaw Bay, MI, USA. The crew extinguished the fire, and the vessel was anchored in the bay. One crew member sustained a minor injury, and minor damage was found to the locker area and equipment.
On 26 November 2025, the bulk carrier "ROBERT S. PIERSON" reported having drifted aground while anchored in the Detroit River off Detroit, MI, USA. The vessel was refloated by a US tug and towed to Windsor, ON.
On 02 August 2025, the bulk carrier "ROBERT S. PIERSON" reported having sustained a propulsion problem while manoeuvring out of the Soo Locks near Sault Ste. Marie, ON. The vessel proceeded downbound to an anchorage where the crew resolved the problem and the vessel resumed its voyage.
On 25 April 2025, the bulk carrier "ROBERT S. PIERSON", reported having sustained a total loss of power while maneuvering at the approach of the MacArthur Lock downbound in the St. Mary's River near Sault Ste. Marie, MI, USA. The crew resolved the situation, and the ship continued its voyage.
On 13 October 2024, the bulk carrier "ROBERT S. PIERSON" reported being disabled with a total failure of its steering system on Lake Superior off Whitefish Bay, MI, USA. The vessel was anchored to assess the issue. The crew lowered a workboat and found that the rudder was missing. The vessel was later towed to Superior, WI, USA for repairs.
On 24 May 2024, the bulk carrier "ROBERT S. PIERSON", with 18 people on board, reported having run aground on Lake Michigan off Muskegon, MI, USA. The vessel freed itself and was anchored for a damages assessment.
On 19 May 2024, the bulk carrier "ROBERT S. PIERSON" reported having sustained a total failure of its steering system on Lake Huron off Port Sanilac, MI, USA. The vessel proceeded to Calcite, MI, USA for repairs.
On 13 October 2022, the self-unloading bulk carrier "ROBERT S. PIERSON" reported that it had struck the dock on Lake Ontario in Colborne, ON. The vessel proceeded on its intended voyage to Clarkson, ON to unload and conduct repairs.
Recorded marine occurrences naming this vessel.
Operational Status
Making way at sea speed on its latest broadcast.
Read from the single most-recent AIS broadcast we hold for this hull — we keep no position history, so this is a point-in-time posture, not a dwell inference. Derived in-house from our own AIS feed; weight it by the broadcast age above.
Arrivals, time in port and the load/discharge inferred from the draught change — detected from AIS track history. An open call means the vessel is still in port (no departure observed yet).
Method: each call is a run of fixes inside a port’s geofence confirmed by a stop (or an AIS gap); load/discharge is the sign of the draught delta over the call. Indicative — arrivals before our AIS history began read from the first observation.
Time-in-port summed by port from the AIS-detected port-call history — the ports this vessel has spent the most time at, longest first.
Based on 8 completed calls observed since — open calls (no departure yet) are excluded. The distribution sharpens as AIS history accrues.
Composite Risk
Multiple adverse factors, or a hard ship-specific signal, lift this hull above the fleet norm.
A coverage-weighted blend of the 3 components we could read for this hull — the weights renormalise over only the components present, so a thin read is never inflated and a hull is never credited a “safe 0” for a signal it has no row for. Higher means riskier. Derived in-house from government-open port-State-control, flag, sanctions and our own vessel data; weight it by the coverage above.
Estimated
Bulker · summer draught 7.5 m · 34 t per cm immersion
Estimate only — modelled from deadweight (hull geometry) using a first-principles hydrostatic model, not measured hydrostatic tables. The design draught it is anchored to is unreliable across the fleet.
density DWT/GT=2.02 is consistent with declared bulker
Declared type is consistent with the class implied by the vessel’s size signals. Inferred via our shared size-based classifier.
Transparency
Behavioural flags raised against this vessel — each shown with the raw evidence behind it. Derived in-house from data we are entitled to publish; informational, not a determination of wrongdoing.
Stopped transmitting relative to the live feed front
Method: gap measured vs the live feed's own max timestamp, not wall-clock. Source: TheMaritime aisstream.io ingest (ais_positions).
Signals are a current-state view: a flag clears once the vessel stops tripping its detector. These are screening indicators, not a substitute for your own due diligence.
Commercial

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