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The principals of MALCOLM TENNANT MULTIHULL DESIGN LTD are Malcolm Tennant ARINA MA, with 45 years of multihull designing and building experience; and Anthony Stanton BE [mech] hons ARINA, who has been with the company for more than five years. Design and draughting assistance is provided by several other designer/draughtsmen. First registered as a  company in 1963 - forty-five years later we are still going strong.

I owned my first catamaran in 1959 and have subsequently built a number of boats. In 1966, along with two friends, I formed GTF International Catamarans, designing and building an International A-Class catamaran to the then new International catamaran rule. Thirty-two of these boats were built, and they won a number of National & International titles. GTF also collaborated on an International B-Class design.

I became a licensed builder of the Olympic Tornado and the Australian designed B2-Class catamaran, the 'Stingray'. In 1969, I designed the first of my larger boats, the catamaran "Vorpal Blade". This was one of the first catamarans of this size to use alloy cross beams. In 1972, I produced the 'Bamboo Bomber', which was a benchmark in stressed plywood construction and the use of wingmasts on bigger boats. This was followed in 1973 by the 'Great Barrier Express' which became the archtype of the larger "off the beach" style of catamaran. More than three hundred [including my own] of this ever popular design were built around the world. It has become a design classic and is currently experiencing a resurgence in interest.

The GBE was followed by a stream of designs, including a number of smaller series production catamarans. The 'Eclipse' and the 'Esprit', in both 3m and 4m, forms were local alternatives to the Hobie cat of this time. Also belonging to this design period, was a full displacement catamaran sail board, very stable but too expensive to have much impact in the marketplace. From 1979, and over the next couple of years, the GBE and its bigger sisters, the 'Turissimo-9' and the 'Turissimo-10' also went into series production in a number of countries including New Zealand, Australia, Brazil, France and the United States. In 1987 another production boat, the 'Northern -11' was launched.

1983 saw the arrival of the 'Wild Thing' Trimaran. Not our first Trimaran design, but the first multihull in the world to be designed for, and built in, the strip plank cedar composite construction that is now so common. "Do it yourself" paper honeycomb sandwich was also used extensively in this design. This flat water sailing Trimaran was very, very light and also featured forward positioned floats to enhance its diagonal stability.

In 1983, we made our entry into the world of power catamarans. We had produced the motor sailer 'Cordova' which motored at a quite respectable 18 to 20 knots. This motor sailer has also sailed at 24 knots and so is truly the best of all possible worlds. To prevent the stern squatting at these sorts of powering speeds we fitted an aft "bustle". It then just seemed a natural progression to fit the same "bustle" to the first of our displacement power boat designs, the 'Nomad'. The "bustle", as designed, turned out to be difficult to build and so for the 'Zenith-47' we turned to a slightly different approach to the stern buoyancy and produced the canoe sterned underbody hull [CS hull]. This, combined with a fine half entry angle, round bilges and an aft flat, proved to be a very low resistance hull with minimal wake characteristics. We can unequivocally lay claim to having originated the CS hull form that has since been adapted by most of the designers of displacement power cats world wide.

We have subsequently to 1983 accumulated a large amount of on the water test data concerning the powering and performance of this type of hull form, which has proven time after time to be probably the most efficient in the world, over a very wide speed range.

Over the years, a steady stream of designs [264 at last count] ranging over the whole multihull gamut, have issued from this office. From small racing craft and folding Trimarans up to large passenger carrying ferries. Our current emphasis is on coastal cruising and ocean going passagemakers [eight of our designs have now crossed the Pacific on their own bottoms] and large motor yachts. But sailing craft are still an important part of our business as evidenced by the new 'Hi-Octane' 15.23m [50'] of open wing racing catamaran. I see a bright future for developing ever larger "super yacht" style power catamarans and we will also be concentrating on a type of catamaran that we have pioneered. This is the motor sailer Catamaran based on our very efficient CS displacement power cat hulls fitted with sails. The result is a boat that will power faster than most power boats and sail faster than most sail boats. Truly a vessel whose time has come.

These many years of experience, and the wide array of designs produced have, over the years, resulted in many hundreds of general and technical articles published in both local and international boating magazines. This expertise has also been recognised by invitations to speak at a number of symposia around the World:

  • the designers panel at the World Multihull Symposium at Annapolis in 1985, 
  • the European Multihull Symposium at Monnickendam in the Netherlands in 1988,
  • again in 1988, the World Multihull Symposium at Newport Rhode Island,
  • a presentation on displacement power cats was made at "IBEX" , Fort Lauderdale, in 1995,
  • May 1999 saw a presentation on displacement power cats and motor sailers at the Sanctuary Cove Boatshow,
  • a similar presentation was made in 2000 at the Longbeach, California, "Trawlerfest".
  • "Yacht-Vision-02" was in Auckland 2002 and was the scene for the latest presentation on "The Power Catamaran As A Long Range Ocean Cruiser"
  • in 2005, a presentation was made on "Power catamarans for ocean cruising" at the 6th Annual International Symposium on Ocean Science and Technology in Busan, Korea.