Who decides the category?
The manufacturer declares it — but for hulls ≥ 12 m (i.e. every 65–78 ft cat) an independent Notified Body must verify the claim against harmonised EN/ISO standards.
Where do 65–78 ft cats fall?
An estimated ≈85% are Category A “Ocean”, ≈10% B, ≈4% C, ≈1% D. A is the default plate across every mainstream builder in the class.
What do designers target?
Category A as the compliance baseline — then real-world margin beyond the ISO minimums, sometimes adding voluntary classification-society certification.
Why 24 m matters
The RCD covers hull lengths 2.5–24 m. That ceiling is exactly why flagship cats are engineered to stop just under it (~23.75 m).
1 · The four CE design categories
Under the EU Recreational Craft Directive (the “CE” categories), a boat’s design category describes the wind and sea conditions the boat is designed for. It appears on the builder’s plate and in the Declaration of Conformity that accompany every certified boat.
A Ocean
Wind: may exceed Force 8 (≥ ~34–40 kn)
Waves: significant height may exceed 4 m
Extended ocean voyages where the boat must be largely self-sufficient in an emergency.
B Offshore
Wind: up to Force 8
Waves: up to 4 m significant height
Offshore passages where quick access to shelter cannot be assumed.
C Inshore
Wind: up to Force 6
Waves: up to 2 m significant height
Coastal waters, large bays, estuaries, lakes and rivers.
D Sheltered
Wind: up to Force 4
Waves: up to 0.3 m significant (occasional 0.5 m)
Small lakes, rivers, canals and other sheltered, benign waters.
“Significant wave height” (Hs) is the mean of the highest one-third of waves; individual waves can be roughly twice Hs — a Cat B boat certified for 4 m Hs will encounter 7–8 m crests.
2 · Who decides the category — and how
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The builder sets the design intent
At concept stage the manufacturer (or the importer placing the boat on the EU market) decides what the boat will be designed for. This is as much an engineering decision as a marketing one: the category drives the structural design loads, stability targets, minimum opening heights, cockpit-draining requirements, bilge-pump capacities and more. For a 65–78 ft cruising catamaran the answer is almost always A — Ocean.
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Engineering to the harmonised EN/ISO standards
The design office documents compliance: hull and bridgedeck scantlings for the chosen category’s loads (including slamming pressures), rig and appendage loads, righting-moment curves, gust-capsize margins for multihulls, downflooding heights of doors, hatches and windows, cockpit volumes and drain times, glazing strength, man-overboard provisions, fuel, electrical and pumping installations.
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Independent verification by a Notified Body
Hulls ≥ 12 m must involve a Notified Body — e.g. RINA, Bureau Veritas, DNV, Lloyd’s Register, IMCI, TÜV or SGS. Production boats normally pass through EU type-examination (Module B) plus production-conformity checks (Modules C, D, E or F); one-offs and heavily customised hulls often use unit verification (Module G), in which the Notified Body examines the individual boat. The body reviews drawings, calculations and test reports, audits the factory and issues certificates.
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CE marking, builder’s plate and paperwork
The builder affixes the CE mark (followed by the Notified Body’s four-digit number) and the builder’s plate stating the design category, maximum load, maximum persons and engine power. The boat ships with a signed Declaration of Conformity, a hull identification number (HIN), and an owner’s manual (ISO 10240) that explains the category and its limits.
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Surveillance and enforcement
Notified Bodies carry out ongoing production surveillance; national market-surveillance authorities can act against non-compliant or mis-categorised boats. Significant owner modifications (rig changes, added structures) fall outside the certified configuration and require re-assessment.
What the Notified Body actually checks — the standards that drive the category
| Standard | What it governs |
|---|---|
| EN ISO 12215-5 / -8 / -10 | Hull structure & scantlings — design loads scale with category (slamming, bridgedeck panels); appendages (daggerboards, rudders); rig loads & attachments |
| EN ISO 12217-2 | Stability of sailing boats ≥ 6 m — righting curves, gust-capcase margins and downflooding (multihull provisions); STIX / AVS route used for monohulls |
| EN ISO 12216 | Windows, portlights and hatches — strength, size limits, heights above the waterline |
| EN ISO 11812 | Watertight & quick-draining cockpits — volumes and drain time after a boarding sea |
| EN ISO 15085 | Man-overboard prevention — lifelines, handholds, boarding means |
| EN ISO 15083 | Bilge-pumping arrangements, with capacities scaled by category |
| EN ISO 9093-1 | Seacocks and through-hull fittings |
| EN ISO 10133 / 13297 | DC and AC electrical installations |
| EN ISO 21487 | Permanently installed petrol & diesel fuel tanks |
| EN ISO 8666 / 10087 / 10240 | Principal data, hull identification number, owner’s manual |
3 · Where 65–78 ft cruising catamarans fall (estimate)
How this estimate was made
No public registry maps CE certificates to individual models, so this split is an informed estimate based on the published specifications of the production and semi-custom builders active in the 19–24 m band (current model ranges), plus observed custom-build practice. The true Category-A share probably lies between ~80% and ~95%. Treat these figures as an order-of-magnitude answer, not a statistic; for commercial use, survey the current model catalogues directly.
Reading the numbers
- A Category A (~85%) — the default plate across Lagoon, Sunreef, Fountaine Pajot, HH, Gunboat, Aquila, Horizon and the heritage brands. Even flybridge giants pass the multihull gust-capcase checks thanks to beam and defined sail plans. Charter-oriented builders need A for inter-season repositioning passages (Caribbean ↔ Mediterranean ↔ Indian and Pacific cruising grounds), and buyers of boats this size expect genuine blue-water capability — a lower plate would cripple resale.
- B Category B (~10%) — usually a deliberate choice rather than an inability: semi-custom one-offs with owner-specified features (oversized openings, folding transoms, extensive glass) that cannot meet A’s downflooding or gust criteria; some older designs still in production; occasional conservative builders.
- C Category C (~4%) — purpose-built day-charter and harbour-cruising cats, and “villa-style” layouts aimed at bay and lagoon use.
- D Category D (~1%) — essentially theoretical at this size: a 70 ft boat limited to 0.3 m significant waves is a floating apartment, not a cruiser.
Typical models in the class — and their usual plates
| Model | Length (approx.) | Style | Typical category |
|---|---|---|---|
| Lagoon Sixty 5 | 19.9 m / 65 ft | Sail | A |
| Lagoon SEVENTY 5 | 22.8 m / 75 ft | Sail | A |
| Lagoon SEVENTY 8 | 23.75 m / 78 ft | Sail | A |
| Sunreef 70 | 21.4 m / 70 ft | Sail | A |
| Sunreef 74 | 22.6 m / 74 ft | Sail | A |
| Fountaine Pajot Alegria 67 | 20.3 m / 67 ft | Sail | A |
| HH 66 | 20.1 m / 66 ft | Sail (performance) | A |
| Gunboat 68 | 20.7 m / 68 ft | Sail (performance) | A |
| Aquila 70 | 21.3 m / 70 ft | Power | A |
| Horizon PC74 | 22.6 m / 74 ft | Power | A |
How to verify a specific boat
- ✔ Check the builder’s plate (category, max load, max persons, power).
- ✔ Ask for the Declaration of Conformity and the Notified Body number after the CE mark.
- ✔ Confirm the HIN matches the certification documents.
- ✔ Read the category and operating-limits section of the owner’s manual.
- ✔ For semi-custom boats, ask which conformity module was used (B+C/D/E/F for series boats, G for unit verification).
4 · Other classifications you will encounter
The CE categories are mandatory for the EU market, but they sit among several parallel systems with different purposes:
| System | Legal status | What it covers | Who issues |
|---|---|---|---|
| CE design category (RCD) | Mandatory to sell in EU/EEA | Design & construction; category = intended conditions | Builder declares; Notified Body verifies |
| Classification (RINA, BV, DNV, LR, ABS) | Voluntary (often required by insurers/commercial registries) | Structural strength, systems, periodic surveys; service notations define sea areas | Classification society |
| Commercial/charter codes (UK MCA SCV, FR Division 240, etc.) | Mandatory when operated commercially | Crewing, safety equipment and actual permitted operating areas | Flag/state administration |
| World Sailing Offshore Special Regulations | Mandatory for races/rallies under those rules | Equipment & crew preparation for offshore racing (Categories 0–3) | World Sailing / organisers |
Classification societies
Optional structural and systems certification (e.g. Lloyd’s Register special service craft rules, RINA pleasure-yacht notations, BV, DNV, ABS). Common for charter-registered or heavily insured boats; typically deeper and more survey-intensive than CE.
Commercial & charter codes
If the catamaran earns money, its operating area becomes legally defined — e.g. UK MCA SCV categories (0: unrestricted; 1: ≤150 nm from haven; 2: ≤60 nm; 3: ≤20 nm; 4–6: day-trip/near-shore/sheltered), or France’s Division 240 zones. These bind more than the CE category does.
Racing safety categories
World Sailing’s Offshore Special Regulations (0 trans-oceanic → 3 short offshore) govern equipment and crew preparation for events — a different concept entirely from design categories.
National frameworks
The US has no CE equivalent for pleasure boats (USCG manufacturing rules plus voluntary ABYC standards and NMMA certification); Australia grades commercial vessels from “unrestricted” down to “smooth waters”; post-Brexit Great Britain requires UKCA marking. In practice the EN/ISO suite is the worldwide de-facto baseline.
Above 24 m
The RCD stops at 24 m hull length. Beyond it, commercial yachts fall under codes such as the Large Yacht Code (LY3), private yachts answer to their flag administration, and class becomes routine — which is exactly why flagship cats are engineered to stop just under the ceiling.
Categories as structural inputs
The same A–D scale is embedded in ISO 12215-5: design pressures and slamming loads scale with category. Choosing “Category A” literally thickens the boat — it is an engineering input from the first lines drawing, not a label added at the end.
5 · What designers of big cruising cats actually design for
The Category A engineering baseline
- Structure to ISO 12215 Category A loads — including slamming pressures on bridgedeck and wetdeck panels, daggerboard/rudder and rig loads (12215-8 / -10).
- Stability via the multihull provisions of ISO 12217-2 — gust-capcase margin and downflooding heights, not the monohull STIX/AVS route.
- Cockpit draining (ISO 11812), glazing (ISO 12216), MOB prevention (ISO 15085), pumping capacity (ISO 15083) at Category A levels.
- Design intent assumes the boat will genuinely make ocean passages: build-yard delivery legs, seasonal repositioning, and owners’ blue-water itineraries.
Beyond the minimums — typical practice at this size
- Bridgedeck clearance chosen to limit slamming in real short seas, not merely to pass panel-load checks.
- Reinforced laminates and foam cores in slamming zones; watertight or crash bulkheads forward; escape hatches from hull accommodations.
- Redundant bilge systems with alarms; ventilation paths designed against water ingress; storm shutters or laminated glass for large glazing.
- Documented heavy-air sail plans, high safety factors on rig and steering gear, serious anchoring arrangements.
- Extensive tankage and energy autonomy — solar arches, hybrid or parallel drives on power cats — reflecting how these boats are actually used.
- Optional class certification (RINA, BV, LR, DNV), especially for charter-registered hulls.
The real trade-offs engineers manage
- Windage vs stability: flybridges and hardtops add area high up; designers recover gust-capcase margin through beam, low weight distribution and tighter sail plans.
- Clearance vs volume: the volume race pushes accommodations down and wide; clearance protects structure and comfort offshore.
- Downflooding: large opening transoms, side access doors and low ports are the classic watch items when chasing a Cat A plate on a big-flybridge design.
- Performance brands are Cat A too: HH, Gunboat and their peers certify A — beam and low centre of gravity make the gust-margin maths comfortable even with large rigs; their choice is where to spend the margin (speed vs structure weight).
6 · Frequently asked questions
Is the CE category a legal limit on where I can sail?
No. It is a design-intent declaration for placing the product on the EU market. Nothing legally stops a Category C boat from crossing an Atlantic — but insurance, charter contracts and good seamanship may all object. Operating limits acquire legal force through commercial vessel codes or event rules, not the RCD.
Was a Category A boat actually tested in Force 9 conditions?
No. Compliance is analytical — calculations and component tests against harmonised standards. No authority sea-trials a boat in a storm. “A” describes the conditions the design is intended for, verified on paper and in the factory.
Why do so many big cats stop at ~78 ft / 23.75 m?
The RCD applies to hull lengths from 2.5 m to 24 m. Above 24 m you leave the pleasure-craft regime: load-line rules, commercial yacht codes, class and manning expectations arrive. Builders deliberately top out just under the ceiling — hence hull lengths like 23.75 m, even when LOA with pulpit and davits is advertised above 24 m.
Can I cross an ocean in a Category B boat?
Usually legal, sometimes sensible, occasionally stupid. The category tells you what the boat was designed and verified for — not its absolute capability. Judge the actual design, loading, condition and weather, and your insurer’s position.
Do CE categories matter outside the EU?
Only the EU/EEA legally requires them (and post-Brexit Great Britain under its UKCA equivalent) — but because European certification is the de-facto global benchmark, most non-EU builders certify anyway, and brokers, insurers and buyers worldwide quote the category as shorthand for capability.
Does Category A mean better built than Category B?
Not necessarily. The category says nothing about build quality, maintenance or seakeeping comfort — only that the design met A-level minimums. A meticulously built, conservative Category B design can outperform a marginal Category A boat offshore.
I added a flybridge or changed the rig — is my category still valid?
The certification covers the assessed configuration. Significant structural or stability-relevant changes require re-assessment by a Notified Body, and your insurer will likely want to know too.
Who polices all this?
Notified Bodies audit at the design and production stage; national market-surveillance authorities enforce afterwards. A mismatch between the declared category and the actual engineering makes the boat a non-compliant product.