A sailing yacht secured alongside a quiet marina pontoon with doubled dock lines and fenders set before a named windstorm

Guides

What a named-windstorm deductible really costs you

The named-windstorm deductible applies to a total loss on the same basis as a repair: 10% of the hull value on your policy schedule, so a $500,000 yacht pays out $450,000.

Owners also call it a named storm deductible. It is the largest single figure in a storm-season yacht policy, and almost everything written about it treats it as a repair problem. The clause below, from the London Marine Insurance Services wording we hold, is the one that decides a total loss.

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10%: Of scheduled hull value, not of the claim
$450,000: Paid on a total loss of a $500,000 hull value
1% to 5%: Ordinary hull deductible, same base
Lloyd's: Where the risk sits and the claim is made

In one line

A named-windstorm deductible, also called a named storm deductible, is a separate and higher deductible that replaces your ordinary one when the damage comes from a windstorm a national weather agency has named or numbered. It is a percentage of the hull value shown on your policy schedule, and here that percentage is 10%.

Key takeaways

10% of the hull value specified in the schedule, not of the claim. That is the London Marine Insurance Services wording, quoted below.
It reaches a total loss on the same base. On a $500,000 scheduled hull value, a total loss pays $450,000.
Ordinary hull deductibles on that wording run 1% to 5% of the same figure, so this is two to ten times the number you are used to.
The trigger is naming or numbering by the National Oceanic and Atmospheric Administration, not wind speed and not a local warning.
A signed hurricane plan is a condition precedent to liability. Without one the cover was never granted.
There is no single industry hurricane box. Your Confirmation of Cover decides, policy by policy.

Reviewed by Costas Matheou, licensed insurance agent (Cyprus). Verify his licence and credentials Last updated 16 August 2026. Facts last verified 16 August 2026.

The numbers on this page, with sources

$450,000

Paid on a total loss of a $500,000 scheduled hull value, after the 10% deduction.

London Marine Insurance Services policy wording, FCA 308599

1% to 5%

Ordinary hull deductible, same base, on each and every claim.

LMIS hull deductible endorsements

14 / 7 / 3

Named storms, hurricanes and major hurricanes in an average Atlantic season, 1991 to 2020.

National Hurricane Center

34 knots

Sustained wind at which a system earns a name, which is when this deductible becomes possible.

NHC glossary

1% to 5%

Typical homeowners percentage-deductible band, against 10% here.

Insurance Information Institute

Lloyd's

Where the risk is underwritten and the claim is made. Specialist syndicates price and underwrite it, and World Yacht Insurance is an introducer that carries no risk.

Lloyd's of London

Definition

What is a named-windstorm deductible?

It is not an extra charge, and it is not a separate policy. One line inside your hull and machinery cover swaps a small number for a large one, for a single category of peril. Ground the boat or lose the rig and you are back on the ordinary deductible.

Percentage deductibles are the standard tool wherever a single weather event can damage thousands of insured items at once, which is why they turn up in property cover as well as marine. What differs between products is the base the percentage comes off, and that is where most owners lose the thread.

Owners get two things here backwards. The deductible is fixed the day the policy is written, not the day the storm arrives, because that is when the schedule figure is fixed. And it takes no notice of how bad the damage is.

A named storm that costs you a bimini and a stanchion produces the same deduction as one that costs you the boat. Whether a loss lands in that category at all is settled by the National Hurricane Center glossary definition of the peril, not by the size of the repair bill.

A close crop of a printed marine insurance schedule on a chart table beside a brass parallel rule

The base

Is the 10% taken from your claim or from your hull value?

From the hull value on your schedule. The London Marine Insurance Services wording is explicit, and it is worth reading in full rather than in summary, because the sentence answers a second question at the same time.

Loss or damage to the vessel related to or resulting from any named or numbered windstorm or weather pattern as defined by the National Oceanic and Atmospheric Agency or any equivalent government organisation shall be subject to a 10% deductible of the hull value specified in the schedule and shall apply to all claims including actual and/or constructive and/or compromised total loss of the insured vessel.

London Marine Insurance Services yacht policy wording

That is the London Marine Insurance Services yacht wording. The firm holds Financial Conduct Authority firm reference 308599, and the risk sits with underwriters at Lloyd's of London.

There is a reason the base is the value rather than the claim. This is an agreed-value contract: the wording insures the vessel for one hundred percent of its agreed value, and applies that provision to partial and total losses alike. One figure, fixed when the policy is written, sets the ceiling on what underwriters will pay, and the deduction comes off that same figure. Move the agreed value and you move both at once.

Run it through a partial loss

Your schedule shows a hull value of $500,000. A named storm puts $60,000 of damage into the boat. The deductible is 10% of $500,000, which is $50,000, so underwriters pay $10,000 and you carry the rest. Had that storm done $40,000 of damage instead, nothing would be paid at all, because the loss sits under the deduction.

That second case surprises people. It is the ordinary consequence of a value-based deductible: under a claim-based figure a $40,000 loss would still produce a payment, and here it produces none.

First-hand

We work off the policy wording itself. When an owner asks what the storm deductible actually is, we read the clause rather than repeat what the market says about it, because the clause is the thing that will be applied to a claim.

Costas MatheouLicensed insurance agent (Cyprus)

The consequence

What happens if the yacht is a total loss?

The same 10% comes off. On a $500,000 scheduled hull value, a total loss pays $450,000, not $500,000. This is the part of the clause almost nobody publishes, and the wording states it in the same breath as the deductible itself: the deduction shall apply to all claims including actual and/or constructive and/or compromised total loss of the insured vessel.

That ending is deliberate. The obvious objection to a value-based deductible is that surely it cannot apply when the whole value is being paid out, and the clause answers that objection inside its own sentence. There is no total-loss carve-out to hunt for. The wording closed the gap before anyone could ask.

The three kinds it names are not interchangeable, though each ends in the same place

Actual total loss: The vessel is gone, or damaged beyond any prospect of recovery.
Constructive total loss: The vessel survives, but the cost of recovering and repairing her exceeds her agreed value, so she is treated as lost.
Compromised total loss: Neither side wants the argument, and the claim is settled at a figure both accept.

Whichever applies, the claim is made at Lloyd's of London, where the risk is underwritten, and it settles less the deduction. The wording carrying that term is on the Financial Conduct Authority register under London Marine Insurance Services, firm reference 308599.

This cuts against a common instinct at survey time. Owners accept a modest agreed value to hold the premium down, reasoning that a low value only costs them in a total loss they never expect to have. But on this wording a lower agreed value shrinks the payout and the deduction together. The boat ends up underinsured for the loss that matters most, and the saving turns up as a smaller deduction on repairs that may never happen. It is a trade, and it is not the trade most owners think they are making.

The comparison

How does the 10% compare with your ordinary hull deductible?

By a multiple of two to ten. The same set of clauses ships an ordinary hull deductible at 1%, 2%, 3%, 4% or 5% of hull value, on each and every claim, and the named-windstorm figure of 10% sits on top of that scale rather than beside it. Both clauses are written against the same base, so an owner who understands their ordinary deductible already understands this one. Only the multiplier changes.

Ordinary hull deductible against the named-windstorm deductible, by scheduled hull value
Scheduled hull value	Ordinary deductible at 1%	Ordinary deductible at 5%	Named-windstorm deductible at 10%
$250,000	$2,500	$12,500	$25,000
$500,000	$5,000	$25,000	$50,000
$1,000,000	$10,000	$50,000	$100,000

Source: London Marine Insurance Services hull deductible endorsements and the named-windstorm deductible clause. That firm is FCA-authorised under reference 308599. The general principle that percentage deductibles are set against insured value rather than against the claim is set out by the Insurance Information Institute.

The two clauses use different words for the same idea, and neither of them means an annual cap. The windstorm clause applies its deduction to all claims; the ordinary hull deductible endorsements apply theirs on each and every claim. So this is not an aggregate you satisfy once and then forget: if two named storms damage the boat in one season, the deduction applies to each claim separately. In an average Atlantic year of 14 named storms and 7 hurricanes, a boat sitting in the wrong place for a bad six weeks can meet it twice.

The trigger

What actually triggers it, and how does a storm get named?

Naming, not wind speed. The clause defines the peril as any named or numbered windstorm or weather pattern as defined by the National Oceanic and Atmospheric Agency or any equivalent government organisation, so the deductible fires the moment a meteorological agency attaches an identifier, regardless of how hard it is blowing over your boat. A tropical storm that never becomes a hurricane still triggers it. A vicious unnamed squall does not.

Two words in that definition do more than owners expect, and the market almost never mentions either.

Or numbered: Systems carry a number before they earn a name. A tropical depression is designated numerically, and the clause reaches it there. Waiting for a name before treating a system as a named-windstorm event misreads the cover by one stage of a storm's life.
Or any equivalent government organisation: Outside the Atlantic it is the national meteorological agency that names systems, and the clause follows them. That is what makes this term work on a worldwide policy rather than a Caribbean one, and it is why the same deductible can attach in the South Pacific or off Queensland.

A system is named when sustained winds reach 34 knots, per the National Hurricane Center glossary. The Atlantic lists themselves are maintained by a World Meteorological Organization committee on a six-year rotation, which the National Hurricane Center sets out here, and the National Association of Insurance Commissioners describes the same trigger from the regulator's side of the table.

Worth stating as a negative: the Saffir-Simpson category has nothing to do with whether the deductible applies. Category measures intensity. Naming decides cover, so a named tropical storm and a Category 5 hurricane engage the identical clause.

A word on trigger windows. Some policies in the wider market define a period around the storm, commonly from a day before naming to two days after it is downgraded, inside which any loss is treated as named-windstorm damage. That construction is a market convention, not a term of this wording, so check your own schedule rather than assume it.

The precondition

Why does the signed hurricane plan decide whether you have cover at all?

Because without one the cover was never granted, so there is nothing to take 10% of. This is not a paperwork requirement that a claims handler might overlook.

It is a condition precedent to liability under this Policy that a signed and dated Hurricane Plan is to be agreed by underwriters prior to cover being granted for Named Windstorm coverage.

London Marine Insurance Services, Hurricane Plan Clause

Condition precedent to liability is a term of art, and it bites harder than a warranty. The obligation to pay never arises unless the condition is satisfied first. The sequence in the sentence matters too: the plan is agreed by underwriters prior to cover being granted. A plan produced after a storm is not late paperwork. It is evidence that the cover was never in force for that peril.

The company that phrase keeps is the clearest guide to how seriously the wording treats it. Across the whole document, condition precedent to liability is reserved for three things: the hurricane plan, the signed proposal form agreed within fourteen days of attachment, and the captain's resume, loss record and licence. Everything else in the policy is a term, an exclusion or a warranty. These three are gates.

What a credible plan responds to is set out in the National Hurricane Center preparedness guidance: where the boat goes, who moves her, by when, and what happens if that person is not in the country. Most plans commit to a haul-out, a relocation or a tie-down at a named facility, and the commitment is the point.

First-hand

Owners kept asking what a hurricane plan is supposed to contain, so we built the generator that writes one and we send it in with the submission rather than leaving people to guess at the format.

Costas MatheouLicensed insurance agent (Cyprus)

The tool is at our boat hurricane plan generator. It writes the document; this page explains what the document buys you. One neighbouring question is worth separating out here. Our guide to what yacht insurance does not cover lists what is excluded outright, and a named windstorm is not on that list. It is covered, on different terms.

A signed and dated plan document weighted by a shackle on a marina pontoon beside coiled dock lines

The geography

Is there a standard hurricane box?

No. There is no single industry hurricane box, and our own primary document declines to draw one. The Insurance Product Information Document for this cover says that geographical windstorm exclusions may apply to your cover, as per your Confirmation of Cover, and that cover is provided as long as you stay within the navigational limits specified in your Confirmation Of Cover.

It routes the geography to the individual policy rather than to a published map, and the numbers go the same way: applicable deductibles apply per the guidance on that same Confirmation of Cover.

That is a stronger answer than pointing out that published maps disagree with each other, although they do. Coordinate sets circulate widely and are rarely sourced. At least one published set is internally inconsistent: Leopard Catamarans has published a box described as north of 30.5 degrees longitude or south of 10 degrees north latitude, where 30.5 degrees is a latitude, and with no east or west bounds given at all. Copying any of them onto your own cruising plan is guesswork dressed as precision.

Owners asking for the box are usually conflating two different things. The season is climatological and public: the Atlantic season runs 1 June to 30 November, which the National Hurricane Center publishes along with the long-run averages. The box is contractual and private. It is a term of your policy, it can differ between two boats moored side by side, and the only document that settles it is your Confirmation of Cover.

Our guide to when the season actually runs deals with when and where the storms come; this page deals with what the policy does about them. If you are cruising the Caribbean, that page is about placing cover for the ground itself, and this one about the single term inside it that owners most often misread.

The disambiguation

How is this different from a homeowners named-storm deductible?

Four ways, and the confusion is common enough to be worth answering directly, because most published writing on named-storm deductibles is about houses.

The base

A marine named-windstorm deductible comes off the hull value on your vessel schedule. A homeowners one comes off the dwelling's insured value. Same arithmetic, different document, and the two figures move for entirely different reasons.

The regulator

Marine cover of this kind is placed into the Lloyd's market and governed by the policy wording that underwriters agree. Homeowners percentage deductibles are supervised by state insurance departments, which set how the deductible must be offered, expressed and disclosed. The South Carolina Department of Insurance bulletin is a plain example of a regulator dictating that detail, and the underlying rule sits in the South Carolina regulations. No equivalent authority sets the terms of a Lloyd's yacht policy.

The trigger

Both fire on a named system, but property cover also uses a wind and hail deductible, which has no naming trigger at all and can apply to an ordinary unnamed storm. The National Association of Insurance Commissioners sets out the distinction. Marine wording here uses the naming trigger only.

The band

Homeowners percentage deductibles typically run 1% to 5% of insured value, per the Insurance Information Institute. The named-windstorm figure on this programme is 10%, which is at or beyond the top of the range a homeowner would recognise.

Since the question comes up: a boat is not covered by your homeowners policy for these losses. A dinghy or a very small craft is sometimes picked up as personal property within tight limits. A cruising yacht is not, and neither is her liability exposure.

Before the season

What should you check on your own policy before the season?

Six checks, each of which points at a document rather than at a memory. All of them take one sitting.

01The hull value on the scheduleIs it still the right number? It sets the payout ceiling and the deduction at the same time.
02The named-windstorm percentageRead it off the schedule rather than assuming the market figure. It is the largest number in the policy.
03The signed hurricane planIs one on file, is it current, and is it dated before cover attached? The order matters, because the clause makes agreement a precondition of the cover being granted.
04The Confirmation of CoverNavigational limits and any geographical windstorm exclusion live there, and nowhere else.
05Per claim, not per seasonConfirm the deduction applies to each claim rather than to an annual aggregate. Two named storms means it twice.
06The season dates you are planning againstThe Atlantic season is 1 June to 30 November.

On the last of those, the National Hurricane Center puts an average year at 14 named storms, 7 hurricanes and 3 major hurricanes.

Geography changes the weight of these checks, not the checks themselves. A boat kept in Florida faces the same clause with a longer exposure window than one that leaves the box in June.

One live reason to read the schedule before a storm rather than after one: Insurance Business reported in July 2026 that boat owners have accused an insurer of applying the wrong windstorm deductible to a claim, an allegation that has not been tested and that the insurer has not conceded. Allegation or not, the owner who already knows which deductible their schedule specifies is in a very different position from the owner finding out during a claim.

A yacht owner's hands flat on a marina-side table beside a stack of policy paperwork and reading glasses

This page is general information about how this term works, not financial advice, and not a description of your own policy. Your schedule, your Confirmation of Cover and the policy wording decide what applies to your boat. If you want the terms for a specific vessel, we can put the question to the market and come back with them.

FAQ

Frequently asked questions

What does a named storm deductible mean?+

It means a higher deductible replaces your ordinary one when the loss comes from a windstorm that a national weather agency has named or numbered. It is calculated as a percentage of the hull value shown on your policy schedule rather than as a percentage of the claim, and on this programme that percentage is 10%.

What is the deductible in marine insurance?+

Ordinary hull deductibles on this wording run 1% to 5% of hull value, applied to each and every claim. The named-windstorm deductible is a separate, higher figure that applies to one peril only. Both are calculated on the same base, the hull value specified in the schedule, so the difference between them is the multiplier and nothing else.

What qualifies as a named storm?+

A system named or numbered by the National Oceanic and Atmospheric Administration, or by an equivalent government organisation outside the Atlantic. Naming happens when sustained winds reach 34 knots, per the National Hurricane Center glossary. The Saffir-Simpson category is irrelevant to whether the deductible fires, and a numbered tropical depression already falls inside the definition.

Does boat insurance cover hurricane damage?+

Yes, under hull and machinery cover, subject to the named-windstorm deductible. Two conditions attach: a signed hurricane plan must be agreed by underwriters before cover is granted, and the boat must be inside the navigational limits set out on the Confirmation of Cover when the loss happens.

What is the difference between a named storm deductible and a wind or hail deductible?+

A named storm deductible needs a named or numbered system before it applies. A wind or hail deductible has no naming trigger and can apply to an ordinary storm. Wind and hail is mostly a property-insurance construct, calculated on a dwelling's insured value and supervised by state regulators, rather than a marine one.

Does the deductible apply twice if two storms hit in one season?+

Yes. The windstorm clause applies the deduction to all claims rather than to an annual aggregate, and the ordinary hull deductible is written on an each-and-every-claim basis. Two named storms producing two claims means the deduction applies to both, and satisfying it once in June does nothing for a second claim in October.

Is there a hurricane box map to check a mooring against?+

There is no single industry box to check against. Coordinate sets circulate and disagree with each other, and some are internally inconsistent. Your Confirmation of Cover is the only document that fixes navigational limits and geographical windstorm exclusions for your policy, so that is the one to read.

Sources

London Marine Insurance Services yacht policy wording, hull and machinery deductible clause and definitions (held by this desk).
London Marine Insurance Services Yacht and Liability Clauses and Endorsements: hull deductible endorsements and the Hurricane Plan Clause.
London Marine Insurance Services Insurance Product Information Document, restrictions and navigational limits.
National Hurricane Center: season climatology, glossary, naming procedure and the Saffir-Simpson scale.
Financial Conduct Authority register, firm reference 308599 (London Marine Insurance Services Ltd).
Insurance Information Institute and the National Association of Insurance Commissioners on percentage deductibles in property cover.

Reviewed by Costas Matheou, licensed insurance agent (Cyprus).

Last updated 16 August 2026. Facts last verified 16 August 2026.

Coverage terms, premiums and deductibles on this page are indicative and not financial advice. Cover is subject to underwriting, survey and the policy wording.