Design Categories for Yachts Under 24 m

For recreational craft under 24 m, the most common classification is the CE design category (A/B/C/D) under the EU Recreational Craft Directive / Regulation (RCD/RCR) and the UK Recreational Craft Regulations. It is also mirrored in the ISO 12217 stability and buoyancy standards.

1. What the categories mean

Category	Name	Design wind / waves	Typical intended use
A	Ocean	Wind > Beaufort 8; significant wave height > 4 m	Long ocean passages, remote bluewater cruising
B	Offshore	Up to Beaufort 8; up to 4 m	Offshore cruising, not extreme ocean conditions
C	Inshore	Up to Beaufort 6; up to 2 m	Coastal and inshore sailing
D	Sheltered	Up to Beaufort 4; up to 0.3 m (occasional 0.5 m)	Sheltered waters, small lakes, canals, estuaries

These are design limits, not a weather forecast or a guarantee. A boat may have several ratings at different maximum loads/persons, e.g. A12 B14 C16 D20, meaning it is Category A only when loaded to the Category A limit.

2. Who decides, and how?

The manufacturer/builder is legally responsible. They choose the intended design category and declare it in the Declaration of Conformity, CE plate and owner’s manual. It is not assigned by a government weather service or automatically by the coast guard.
The designer/naval architect does the technical work. Stability, buoyancy, freeboard, downflooding, cockpit drainage, maximum load and related calculations are performed to the relevant standards. For sailing boats of hull length ≥ 6 m, the key standard is usually ISO 12217-2. Other relevant standards include ISO 14946 (maximum load), ISO 11812 (watertight/quick-draining cockpits), ISO 15085 (man-overboard prevention) and ISO 8666 (principal data).
A notified body or classification society may verify compliance. Under the EU RCD/RCR, boats of 12 m and over, or boats in Category A or B, normally require involvement of a notified body (e.g. EU type-examination, unit verification or an approved quality-assurance system). Examples include RINA, DNV, Bureau Veritas, Lloyd’s Register, IMCI and others. Smaller C/D boats under 12 m can often be self-certified under Module A.
The category is load-dependent. A large catamaran may be Category A with a small crew and light load, but only Category B or C with full tankage, stores, toys and many guests. Overloading can invalidate the stated category.
Market surveillance can check it. Authorities can audit the manufacturer’s technical file, calculations and CE marking. A false or unsupported category declaration is a legal non-compliance.

3. Estimated distribution for 65–78 ft cruising catamarans

The following is an estimate for popular production cruising catamarans in the 65–78 ft range (roughly 19.8–23.8 m hull length) sold into the EU/UK recreational market. It refers to the primary/headline design category—the highest category the boat is marketed and certified for—not every category printed on the plate.

Primary / headline category	Estimated share	Notes
A – Ocean	~90–95%	Dominant for bluewater cruising catamarans: Lagoon, Fountaine Pajot, Bali, Sunreef, Privilege, Catana, Outremer, HH, Gunboat, Balance, McConaghy, etc. Most are CE A at a reduced load.
B – Offshore	~5–10%	Some coastal/charter-oriented or very heavy/high-volume boats may have B as the headline category, or offer A only at a very restricted load. Custom or non-CE boats may fall here.
C – Inshore	~0–2%	Rare in this size for a true cruising catamaran. If present, usually due to a specific commercial/coastal role or a very unusual configuration.
D – Sheltered	~0%	Effectively none for 65–78 ft cruising catamarans.

Important nuance: Most large cruising catamarans list all four categories on the CE plate with different maximum persons/loads—for example, Category A for 8–12 people, B for 12–14, C for 16, D for 20. So if you count “appears anywhere on the CE plate,” the percentages for B/C/D are much higher. If you count “what the boat is primarily designed and marketed for,” Category A dominates.

These percentages are market estimates, not official statistics. Certification varies by model, model year, options, tankage, interior layout, load condition and whether the boat is sold as a recreational craft, commercial craft or custom build.

4. Are there other classifications?

Classification / scheme	Typical use	Who uses it
CE design categories A/B/C/D (RCD/RCR, ISO 12217)	Recreational craft under 24 m in EU/UK	Manufacturers, designers, notified bodies
Classification society rules – DNV, Lloyd’s Register, ABS, Bureau Veritas, RINA, etc.	Yacht class, construction survey, plan approval, charter/commercial compliance	Owners, builders, charter operators, insurers, flag states
Flag-state commercial codes – e.g. UK MCA Small Commercial Vessel Code, MCA Category 0–6, similar schemes in other flags	Commercial operation: charter, passenger carrying, coding for area of operation	Commercial operators, flag administrations, surveyors
World Sailing Offshore Special Regulations (OSR) – Categories 0, 1, 2, 3, 4	Racing and rally safety equipment/design requirements	Race organizers, offshore sailors, rally participants
US ABYC / NMMA / USCG	US recreational boat standards and certification	US market builders, importers, insurers
Insurance/flag ocean ratings – e.g. “unlimited offshore”, “ocean passage”, “coastal”	Insurance underwriting and flag-state permission	Insurers, owners, flag registries

5. What do most designers of such catamarans design for?

Primary target: CE Category A. For 65–78 ft bluewater cruising catamarans, designers almost always aim for Category A as the headline rating because owners expect ocean-crossing capability and it is a strong marketing requirement.
Multi-category certification. They often design so the boat can be CE A at a reduced load, then B/C/D at higher loads. This gives flexibility for charter, guests, tankage and options.
ISO 12217-2 compliance. Sailing catamarans are assessed under the sailing craft stability/buoyancy standard, with attention to multihull stability, reserve buoyancy, escape hatches, downflooding and cockpit drainage.
Real-world bluewater use. Trade-wind routes, ocean crossings, liveaboard cruising, remote anchoring and long-term self-sufficiency.
Charter and luxury use. Many large catamarans are also designed for charter or luxury coastal use, so comfort, volume, air-conditioning, generators, watermakers and payload matter. This can push the full-load category down to B or C even when the headline is A.
Optional classification. Some owners or operators request DNV, Lloyd’s, Bureau Veritas, RINA or other class certification for insurance, charter, commercial use or resale. This is separate from CE but can be additional assurance.
Not a guarantee. Category A means the boat is designed and assessed to withstand certain conditions. It does not mean it can safely be taken into any weather. Seamanship, weather routing, crew experience, maintenance and loading remain decisive.

6. Practical takeaways

The manufacturer chooses and declares the CE design category; the designer proves it via ISO 12217 and related standards.
For 65–78 ft cruising catamarans, the primary/headline category is overwhelmingly A (Ocean)—roughly 90–95% in the popular production market.
Most of those boats also carry B/C/D ratings at higher loads, so the CE plate may show all four categories.
Check the load condition attached to the category. A boat that is Category A with 8 people may be Category B or C with 20 people and full tanks.
Other schemes exist (classification societies, MCA/flag commercial codes, World Sailing OSR, ABYC/NMMA), but they serve different purposes from the CE recreational design categories.

This information is general guidance, not legal or certification advice. For a specific boat, refer to its CE plate, Declaration of Conformity, owner’s manual and the builder’s technical documentation.