Design Catamarans is run by Andrew Craig, who had his own first steel catamaran (Gemini) built in 1989, as a commercial fishing vessel which he skippered. Andrew decided on this move away from more traditional fishing vessels, as he suffered with a bad back and legs which affected his balance, so he wanted to improve life at sea with a vessel which offered far greater stability and reduced rolling. At the time, there was very little knowledge to source from, of construction, design and the performance of catamarans, as there were very few catamarans operating in Europe, so this proved to be a very steep learning curve, as once completed, this vessel was overweight and slammed badly on the bridge deck when heading into seas, although it was a very good sea boat in beam-on and in following seas. Andrew decided to try and rectify the slamming, as apart from this problem, she was a huge improvement on all traditional mono-hull designs, with vastly increased working deck area and sea keeping capabilities.

Over the next 5 years, the Gemini effectively became a working R&D program, when possible between trips, this included making and trying various pods fitted to the underside of the bridge deck, bulbous bows and hydrofoils, which eventually resulted in stopping all slamming when heading into big seas, increased speed by 1.5 knots and reduced fuel consumption. One of the many lessons learnt during this time, was that many of the standard rules used by naval architects, when designing mono-hulls, do not apply to catamarans and can have a detrimental effect on the design, making the vessel perform badly.

In 1997 after having a spinal operation, Andrew had to come ashore on medical grounds and while convalescing designed the Gemini range of catamarans. In 1999 the company Gemini Workboats was formed, derelict buildings suitable for production were refurbished and production started, after completing the plugs and GRP moulds. Unfortunately, this business, along with many other UK boat yards, had to close in 2010 due to the UK fisheries quota system.

To date over 150 catamarans of between 7m and 16m have been designed and built by Andrew, and Design Catamarans Ltd are now able to offer designs in steel and aluminium to suit almost every marine application.

The benefits of purchasing a design from Design Catamarans Ltd, after decades of studying catamaran hull shape performance, research and development, design and production, this company specialises in designing catamarans, and nothing else. Design Catamarans Ltd can offer a full set of drawings comprising

  • General Arrangement drawings

  • line plans

  • build construction drawings

  • profile plate cutting plans


for steel and aluminium builds, to suit each client’s individual requirements. All drawings will have been certified by the Seafish Marine Survey Department, or other required assigning authority.

Achieving certification for new one-off designs can be very expensive. As a specialist in catamaran design we are able to significantly reduce this cost.

Please note.
It is now a legal requirement for all assigning authorities, to gain the designers authorisation, before any new vessel build may commence. © Design Catamarans Ltd.

DC 7, 8 and 9m

Design Catamaran 10m - 70m


GRP Catamarans

DC 7, 8 AND 9M

This range of fast GRP boats, designed by Andrew Craig, is now in full production near Ipswich, Suffolk.

DC 7, 8 and 9m range

(designed for outboard engines)

Formerly Colne Catamarans, all existing guarantees and contracts on boats built by Colne Catamarans, will be honoured by Design Catamarans.

The DC 7, 8 and 9m range (formerly Colne Catamarans) is highly suitable for: Commercial Fishing, Aquaculture, Angling, Charter, Diving, Survey, Committee Boats, Sight-seeing and Passenger vessels, amongst many other uses.


What benefits could a new DC 7, 8 and 9m offer, compared to a mono-hulled vessel of a similar size?


  • Up to 40 times better stability compared to a mono-hull

  • Considerably less rolling around

  • Up to 50% more deck space

  • Increased and safer deck carrying capacity

  • Easier and safer when working on deck

  • Virtually unsinkable

  • Reduced running costs, maintenance and down time

  • Higher speeds compared to equivalent power from diesels

  • Reduced fuel consumption

  • Minimal through-hull fittings, reducing the risk of flooding

  • Much reduced survey fees

  • Low license requirements

  • Easy single-handed operation

  • Very shallow draft

  • Fewer aches and pains after a rough trip


Compared to our nearest competitor, DC 7, 8 and 9m are wider and therefore more stable, have a higher carrying capacity, are more competitively priced and have higher build quality.


If you would like a brochure and price list, a trip aboard one of these boats, to see the benefits for yourself, or  a full written quotation to meet your specific requirements, please contact us.

Hull design

Why choose a DC 7, 8 and 9m over other catamarans?


These lighter catamarans are designed with little rake on the stem, a very full forefoot and a full hull dead rise, this gives a catamaran hull the required full buoyancy forward all catamarans need when heading into weather, or they will slam on the bridge deck badly.


Many designs on the market have a finer entry bow and weak forefoot to improve speed and this does work to a degree but only in very calm conditions, however as soon as any weather is experienced, the bows bury into the seas and bridge deck slamming starts, which reduces speed and sea keeping dramatically.


With the full hull design, some light slamming is experienced on the hulls as they are so full, but this is far more acceptable for maintaining average speed, fuel efficiency and comfort.


These catamaran hull design rules apply world over, so if any boat designers or builders suggests their catamarans do not slam in any way, we suggest there boats are tested out in poor weather conditions, so this can be experienced first hand before any purchase is made.

Outboards vs diesels fitted in small catamarans

​Andrew Craig has designed and built well over a 150 catamarans up to 16m, fitted with both inboard and outboard engines. He has shown that lighter boats fitted with outboard engines, as well as being faster, are considerably more fuel efficient, and less expensive to build. It is important to note that fitting diesel engines to a boat of this size can increase its weight by around 50%, as diesel engines are heavier, require engine beds, stern gear, steering gear, internal fuel tanks and require much more wiring and plumbing. While a diesel engine is more fuel efficient, when compared with an outboard engine of the same size, a lighter boat fitted with the same size outboard engines has an improved power to weight ratio.


Example: a DC 8m catamaran fitted with 2 x 75hp outboards will weigh around 3 tons, giving 50hp per ton with a top speed of around 23 knots. An 8m catamaran fitted with 2 x 75hp diesels will weigh at least 4.5 tons with just 33hp per ton, giving a top speed of around 12 knots.


Latest builds

Images and descriptions of latest builds of DC GRP boats


Each of these catamarans is designed to the client's specific requirements, which when constructed in steel  are around 50% of the build cost of an equivalent vessel constructed in GRP.

Below are examples of standard designs suitable for commercial fishing. We also design bespoke catamarans to suit almost every marine application.

All our catamaran designs include proven anti-slamming foils as standard.

Please contact us to discuss your requirements.



to a world class design



At Design Catamarans Ltd, our knowledgeable and experienced team are looking forward to designing your next boat. If you would like to get in touch with us, please send us an email or phone 01206 619645.