A MODU is a vessel — which usually puts the Jones Act in play.
‘Mobile offshore drilling unit’ is the umbrella for the rigs that move from well to well — drillships, semi-submersibles, and jack-ups. Because each is a vessel, its crew is usually covered by the Jones Act.
Is a mobile offshore drilling unit (MODU) a vessel, and am I a Jones Act seaman on it?
Generally yes. A MODU is designed to be moved between drilling locations, which usually makes its crew Jones Act seamen. As a seaman you can sue your employer for negligence under the Jones Act, bring an unseaworthiness claim, and receive maintenance and cure.
Key takeaways
- A mobile offshore drilling unit (MODU) is generally treated as a vessel.
- That usually makes its crew Jones Act seamen.
- Seamen get Jones Act negligence, unseaworthiness, and maintenance and cure.
- The Jones Act needs only a light showing of fault; unseaworthiness needs none.
- Status can still be contested, so the specific assignment matters.
The rigs that move from well to well.
A mobile offshore drilling unit (MODU) is a movable rig that drills wells and then relocates — the opposite of a permanently fixed platform. The three main types are the drillship (a ship that drills through a moonpool), the semi-submersible (a column-stabilized floating rig), and the jack-up (a hull that jacks up on legs over the seabed).
All three are vessels, and three workforces typically share their decks — the marine crew; the drilling crew employed by the drilling contractor (Valaris, Noble, Diamond, and others); and rotating service and specialty contractors. Which workforce you were in changes which law applies.
The injuries this work produces.
A MODU concentrates drilling and marine danger together: tripping pipe and pipe-handling crush, falls from the derrick and around the moonpool, dropped objects, crush in BOP and riser work, high-pressure releases and well-control events, crane and lifting incidents, personnel-transfer injuries, and the marine hazards of a unit underway or holding station. The cause is usually equipment that wasn't fit for use or an operation pushed forward without the right oversight.
A vessel — so the Jones Act usually applies.
Under Stewart v. Dutra Construction Co., 543 U.S. 481 (2005), any watercraft practically capable of moving on water is a “vessel” — and a mobile offshore drilling unit qualifies. That status is the gateway to the strongest remedies in maritime law.
A worker assigned to the mobile offshore drilling unit whose duties contribute to its mission, with a connection substantial in nature and duration (the Sanchez / Chandris test), is a Jones Act seaman — with a negligence claim against the employer.
That seaman also has a no-fault unseaworthiness claim if the vessel, its gear, or its crew was not reasonably fit for its purpose.
A service-company or contract worker aboard who is not a crew member can instead sue the vessel for negligence under § 905(b).
On a MODU, the defense rarely argues it isn't a vessel — it argues you weren't really its crew.
Sound like your situation? Calling us is confidential, costs nothing, and starts nothing you don’t choose to start.
Text (713) 489-2297We've litigated the classification fight.
Doyle Dennis Avery tries the cases where the classification is the battle. In the Bermuda forum-maneuver case, a drillship mechanic's case was kept in Texas; in our seaman-status workboat case, a workboat injury was built across the Jones Act, § 905(b), and general maritime law; in our foreign-employer jurisdiction case, a contractor's fall offshore was pursued to recovery.
If you were hurt on this kind of unit, the first job is to establish what it is, who you were to it, and who else was responsible. That early work is what protects the value of the claim.
What the other side will argue — and how it’s met.
A MODU is a vessel in the eyes of maritime law, so the defense fights crew status and fault rather than the unit’s character.
On a vessel the fight is rarely whether it is a vessel — it is whether you were its crew. Seaman status turns on a connection to the vessel or fleet that is substantial in nature and duration (Chandris and Sanchez, roughly 30% of your time) and is provable through assignment and time records. Establishing it opens the full Jones Act and unseaworthy-vessel recovery.
For floating, movable units the defense argues the structure is a fixed facility outside maritime law. Vessel status is a fact question — a structure practically capable of maritime transportation is a vessel — and winning it brings the Jones Act and unseaworthy doctrine to bear instead of a narrower premises regime.
The Jones Act uses pure comparative negligence, so a worker’s own fault reduces a recovery but never bars it — and the hazard is usually the company’s. In one case the firm tried, a jury found the injured worker zero percent at fault.
A worker does not need to prove unseaworthiness to win. Employer negligence under the Jones Act stands on its own — a jury can find negligence even where it does not find the vessel unseaworthy.
A MODU case starts with vessel status, then the hazard.
Mobile offshore drilling units — drillships, semisubs, jack-ups, and drill barges — are vessels because they are practically capable of maritime transportation, a point the Supreme Court settled for movable drilling structures. The firm establishes that status and the worker’s connection to the unit, then reconstructs the drilling, lifting, or deck hazard with a marine-safety expert. The operator and the drilling contractor that owns the MODU usually share responsibility under the Jones Act and unseaworthy doctrine.
A movable drilling unit is a vessel — and its crew are seamen with the full protection that brings.
What to protect while it still exists.
Vessel character, your connection to the unit, and the hazard records all have to be locked down early.
The unit’s class and operating records, your assignment and time records, and the equipment involved establish both vessel status and the negligence case. Preserve them at once.
Tell a supervisor and make sure a written incident report is created. For a serious injury the vessel must also file a Coast Guard marine-casualty report (Form CG‑2692); a missing report is itself evidence of a safety failure.
See a doctor promptly and describe exactly how the injury happened to every provider. An honest, contemporaneous record is the backbone of the case.
You are not required to give the insurer a recorded statement, and early “I’m okay” remarks get used against you. Assume you may be watched, and get advice before signing.
Frequently asked questions about a mobile offshore drilling unit (MODU) injury claims
Is a mobile offshore drilling unit (MODU) a vessel?
Generally yes. A MODU is designed to be moved between drilling locations, so courts usually treat it as a vessel for Jones Act purposes.
Am I a Jones Act seaman if I work on a mobile offshore drilling unit (MODU)?
Usually. If you have a substantial connection to a mobile offshore drilling unit (MODU) in both duration and nature, you are typically a Jones Act seaman, able to sue the employer for negligence and claim unseaworthiness and maintenance and cure.
What is the test for whether something is a vessel?
Courts ask whether the structure is practically capable of being used as a means of transportation on water. Something built to move, such as a drillship or supply vessel, usually qualifies; something fixed to the seabed or permanently moored in place usually does not.
Do I have to prove my employer was at fault?
Not entirely. Under the Jones Act you need only show the employer's negligence played some part, however slight, which is a very worker-friendly standard. An unseaworthiness claim requires no negligence at all, only that the vessel or its equipment was not reasonably fit. Maintenance and cure is owed to a seaman regardless of fault.
What can I recover after an injury on a mobile offshore drilling unit (MODU)?
Recovery is measured by category rather than a fixed amount: past and future medical care, lost wages and lost earning capacity, pain and suffering, and maintenance and cure for a seaman. The total depends on the facts, so no honest lawyer can promise a number up front.
What is maintenance and cure?
Maintenance and cure is a no-fault maritime benefit owed to an injured seaman: maintenance covers daily living expenses and cure covers medical care, until you reach maximum medical improvement, regardless of who was at fault.
What should you do after an injury on a mobile offshore drilling unit (MODU)?
Get medical care and make sure the injury is reported in writing. Preserve evidence early, including incident reports, photos, equipment, and witness names, and do not give a recorded statement or sign anything before talking to a lawyer.
What happens when you text us
Tell us what happened — in your own words, as much or as little as you want.
We review it free. You learn whether maritime law protects you and what your options actually are.
You decide. Nothing is filed, and no one contacts your employer, unless you choose to move forward.
Your conversation with us is confidential. There is no fee unless we win. Hablamos español.
Reach out even if…
- You think the accident was partly your fault — under the Jones Act, your own fault reduces a recovery but does not bar it.
- You already gave a statement or signed something — a release signed under pressure can be challenged.
- You still work for the company — talking to a lawyer is confidential, and retaliation for pursuing a claim can itself be actionable.
- You’re not sure your case is “big enough” — that’s exactly what a free review is for.
What you were working on shapes your claim.
Doyle Dennis Avery LLP represents offshore workers injured on drillships, semi-submersibles, jack-ups, FPSOs, platforms, and the supply, service, and construction vessels that serve them. Tell us what you were on and what happened — a case review costs nothing, and there is no obligation.
This page is general information, not legal advice, and does not create an attorney-client relationship. Whether a worker is a Jones Act seaman, an LHWCA harbor worker with a § 905(b) claim, or covered another way depends on the specific facts, including the structure involved and the worker’s connection to it. Vessel status and seaman status are fact-intensive questions. Prior results do not guarantee or predict a similar outcome. Doyle Dennis Avery LLP · Houston, Texas. This is attorney advertising.
