MARINE · 5 MIN READ
Marine Insurance Foundations and the MIA 1906
Ocean marine is the oldest branch of insurance, and its doctrine was codified in the UK Marine Insurance Act 1906 (MIA 1906), which grew out of centuries of practice at Lloyd's and the historic Lloyd's S.G. Form. Although a British statute, U.S. federal admiralty courts treat it as persuasive authority, and under Wilburn Boat v. Fireman's Fund, where no settled federal admiralty rule exists on a marine insurance question, state law applies. Three foundational doctrines from the Act drive exam questions: utmost good faith, implied warranties, and valued policies. Section 17 makes marine insurance a contract of uberrimae fidei - utmost good faith - and the duty is mutual: both the assured and the insurer must deal in utmost good faith, and breach by either party allows the other to avoid the contract. Section 39 splits the implied warranty of seaworthiness by policy type. In a voyage policy there is an absolute implied warranty that the ship is seaworthy at the commencement of the voyage - fit in design, equipment, manning, fueling, and stowage for the particular adventure - and breach discharges the insurer from the date of breach regardless of due diligence. In a time policy there is no continuing implied warranty, but if the assured, with privity (knowledge), sends the ship to sea unseaworthy, the insurer is not liable for loss attributable to that unseaworthiness. Section 41 adds an implied warranty of legality of the adventure. Section 27 governs valued policies: the value fixed by the policy is conclusive between insurer and assured (absent fraud), which is why pleasure-craft yacht policies are almost universally written on an agreed value basis - a constructive total loss pays the agreed value, not actual cash value. Related doctrines include deviation - departing from the customary route can suspend coverage, with a traditional carve-back for deviations to save human life - and the trading warranties that confine a vessel to stated geographic limits.
Key rules
Utmost good faith in marine insurance is mutual — either party's breach lets the other avoid.
MIA 1906 section 17 imposes uberrimae fidei on both the assured and the insurer, unlike ordinary consumer contracts where disclosure duties run mostly one way.
Why the exam cares: The exam tests the mutuality point directly; distractors describe a one-way duty owed only by the insured.
A voyage policy carries an absolute implied seaworthiness warranty at commencement.
Under section 39(1) the vessel must be seaworthy for the particular adventure when the voyage begins; breach discharges the insurer from the date of breach even if the owner used due diligence.
Why the exam cares: Questions contrast the voyage rule with the time-policy rule, and the absolute (no-excuse) character is the tested nuance.
A time policy has no continuing seaworthiness warranty — but privity defeats recovery.
Under section 39(5), if the assured knowingly sends the ship to sea unseaworthy, the insurer is not liable for loss attributable to that unseaworthiness; otherwise coverage stands.
Why the exam cares: The privity qualifier is the discriminator between right and wrong answer choices on time-policy questions.
In a valued policy the agreed value is conclusive between the parties absent fraud.
Section 27 makes the stated value binding for total and partial losses, which is why yacht constructive total losses settle at agreed value rather than depreciated ACV.
Why the exam cares: Agreed value versus ACV is a recurring yacht and hull settlement question.
Where admiralty law is silent, marine insurance disputes follow state law.
Wilburn Boat v. Fireman's Fund held that absent a settled federal admiralty rule, state law governs marine insurance questions; most coastal states enforce agreed-value clauses.
Why the exam cares: This case is the tested bridge between federal admiralty doctrine and state insurance law.
Numbers to memorize
- 1906 — Marine Insurance Act (UK), the codification U.S. courts treat as persuasive marine authority
- Section 39(1) vs 39(5) — voyage-policy absolute seaworthiness warranty vs time-policy privity rule
Common traps
- Applying the voyage seaworthiness warranty to time policies — remember a time policy has no continuing implied warranty; only privity to unseaworthiness bars recovery.
- Treating utmost good faith as the insured's duty alone — remember section 17 is mutual, and breach by either side lets the other avoid the contract.
- Settling a yacht constructive total loss at ACV — remember valued policies pay the conclusive agreed value absent fraud.
- Assuming any deviation voids the adventure — remember deviations to save human life are traditionally excused, while route departures for convenience are not.
For every warranty question, first classify the policy as voyage or time - the correct answer nearly always turns on that single classification.
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