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Philosophy behind the Ethnic Approach

Written for 'Multihulls World'
By James Wharram
James and Hanneke in design studio with Amatasi model
James and hanneke with a finished model of the Amatasi. These models let us design and study details at a small scale.

Inspired by the French sailor Eric de Bisschop, I became a pioneer of catamaran design. Like Eric de Bisschop my early voyages in the 1950s were driven by a wish to prove that the Pacific double canoe was a seaworthy vessel, capable of crossing oceans. My first catamaran designs were based on studies in museums and libraries, making me one of the early experimental marine archaeologists.

Watercraft is one of Man’s earliest artefacts. Early Man migrated to the far reaches of the world via the coasts and rivers. Man first reached Australia more than 50,000 years ago. He must have done so by watercraft because there was always a substantial water gap between what is now Indonesia and Australia, a gap no other mammal managed to cross.

Watercraft and living on and by the sea is therefor part of our genetic make-up, or in Jungian psychology, it is one of the ‘arch-types of our sub-conscious’. It explains modern Man’s attraction to the sea, swimming and sailing.

Hanneke at work in the design studio
Hanneke works on a half model of the Mana hull based on an initial lines drawing. This lines drawing is the result of concept discussions and idea sketches drawn during an intensive brainstorm between James and Hanneke.

We design boats to fulfil this sub-conscious need by not only supplying a boat design, but also encouraging - through design - a lifestyle suitable for sea living, using simplicity as its basis. This allows people to get in touch with the archaic Sea Nomad in their subconscious.

Designing in this way requires a strong design discipline. The aim for simplicity leads us to look for the most appropriate, cost-effective building materials. Since the early 1980s we have developed the use of wood/epoxy/glass into a simple system, which we have constantly improved on.

Using this system we have designed a whole range of wood/epoxy catamarans, from 17ft – 65 ft, all keeping to the strict discipline of simplicity and keeping cost low, while achieving all the needs of a fast, elegant, safe, STABLE, seagoing design.

Half model of Mana hull, next to lines drawing
The half model allows us to make adjustments to the panel shapes for the stitch and glue design.

These are the design disciplines we consistently adhere to:

  • Traditional sailing ship hull proportions, i.e. modest freeboard, never higher than 13%. This keeps windage to the minimum, requiring minimum driving force (i.e. sailarea and engine power)
  • Slim hulls of around 12:1 or slimmer to reduce wave drag, to achieve speed without the need for excessive rigs
  • High stability, achieved through low rig proportions, so the boat will always look after the crew, not the other way around
  • Flexible hull joining, allowing the boat to flow over the seas, reducing stresses on the structure and increasing durability

Keeping boat weight low is an advantage in an unballasted, form-stable catamaran, as it increases load carrying capacity, essential for a cruising catamaran. The latest high tech designers achieve low weight with the use of expensive, exotic materials and highly industrialised building methods. These are not appropriate for the majority of sailors working on a low budget. We achieve low weight by making every piece of cabin furniture also a structural strength element, thereby saving both weight and cost. This way we can use moderate cost, easy to use materials and still achieve the light weights of the high-tech more elaborate designs.

James inspecting the Mana hull model
James studies the plywood full hull model that is made after the cardboard half model.

To achieve maximum stability and still high speeds we developed a new simple low aspect ratio rig, which we call the Wharram Wingsail Rig, which can be in one-masted or two-masted configuration, keeping C of E low. This rig combines efficient aerodynamics with great simplicity and moderate cost due to the minimum use of expensive hardware. It predates the high-tech square headed sail rigs seen on most of the recently designed multihulls by nearly 20 years.

Present day multihulls are strongly influenced by modern styling, following the same trends as car and luxury hotel design. They are often based on previous generation multihulls with new styling and popular modern features added, without ever going back to basic design principles.

Hence we see higher and higher freeboard to accommodate all the urban luxury needs of modern Man, as well as higher and higher rigs to achieve the urge to go faster than others in this ‘competitive world’. Higher freeboards mean higher windage and hence a need for larger rigs and larger engines, leading to higher weight, leading to fatter hulls, leading again to larger engines, rigs etc. etc.

Hanneke drawing boat plans in the design studio
Final stage of the design process is drawing up the plans.

However my concern is the latest trend in expensive luxury fast cruising cats that achieve speed through very large rigs modelled on racing multihulls, with aspect ratios of 150% LOA.

We are seriously concerned about the stability of these catamarans. They are often shown with one hull lifted clear of the water, sailing on the edge of capsize (remember that once the windward hull is lifted clear of the water the righting moment decreases very rapidly on a catamaran). Film footage of one of these designs nominated for Sail Magazine’s prestigious “Best Boat 2013” award, shows her sailing with the windward hull kissing the surface in winds of just 12-18 knots!

It should always be remembered that multihulls are FORM-STABLE vessels with a very long history. I have taken my design inspiration from the fantastic ancient boats of the Pacific that made long ocean voyages before any other type of vessel. This is a heritage we modern designers must be proud of and not abuse by forcing it to conform to our luxury, urban, competitive Western demands.

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