FEATURE | Thai aluminium: shape and weld

A 19-metre monohull takes shape in the shop

When Khun Namchai Sakunchoknamchai was seven years old he liked cars, so he built himself one out of wood. Decades later, he was building those big beautiful custom tour buses that are a feature of Thai roads. When he wanted a 30 million baht (US$900,000) machine for shaping rolled aluminium sheet, he designed and built one for less than nine million THB. This machine is just one of the impressive array of technologically sophisticated machines at his factory in Suphanburi, Thailand.

The computer-controlled, 20,000-tonne press for shaping aluminium panels

Recently, he has added an aluminium boat building company, Sakun C, to his ever-growing operations. Utilising machines like the computer-controlled, 2,000-tonne press that he uses to shape bus panels, the team is able to shape the side panels for the twin hulls of the 18- by 6.2-metre catamarans that he is building for the recently formed Chao Phraya River Line. This results in a pair of hulls with virtually no vertical welds for greater beauty and strength but also for ease of fabrication.

Welding the pressed hull panels together for a new catamaran at the ship in Suphanburi, Thailand

The firm hires untrained workers and trains them in-house to their exacting welding standards. The each side of catamaran hulls has two panels that are joined by a lift strake that becomes a splashguard toward the bow. A welder, using the latest technology, runs a perfect bead the full length of the hull. Other welding of the extruded beams that, are shaped into frames, is done by several highly accurate robot-welders.

One of the 18-metre catamarans at work on the Chao Phraya River

Capt. Somsal Sakeanok at the helm of one of the new catamarans

The result is a handsome commuter ferry that carries passengers to and from shopping malls along the crowded waters of Bangkok’s Chao Phraya River, with a capacity for 100 passengers inside on the main deck and another 20-passengers up-top. Passengers on the upper deck are accommodated on aluminium bench seats fabricated by Sakun C from panels made by their own extruding machine.

Engines are accessed by moving a set of seats

Each of the hulls is fitted with a Cummins NT855 engine producing 300 kW each at 1,800 rpm. The engines turn conventional propellers through Dong-I gears with 2.51:1 reduction. This gives the catamaran a comfortable river speed of 12 knots and a maximum speed of 21 knots . As of early April 2019, there were three of these practical vessels in operation and one in build.

One of Sakun-C’s 19-metre monohulls at work on the Chao Phraya River

In addition to the catamaran, Sakun-C has modified the design of one of its fast 19-metre monohull tourist boats for the Chao Phraya River Line. A number of these boats have been built for domestic and export customers. Typically they are fitted with four 250hp (190kW) outboard motors, but for the river, where less speed is allowed, the hull bottom was slightly modified to match a Cummins diesel inboard. The river boat is powered by a single Cummins QSB6.7 diesel producing 180kW to a conventional propeller for a light boat speed of 15 knots.

Left to right, R&D Patdanai Satapattayanont, Managing Director Namchai Sakunchoknamchai, Secretary Doungporn Pimsin with catamaran model

Chao Phraya River Line’s founder Cdr. Parinya Ruckwatin, with a background that includes ten years in the Royal Thai Navy, is excited about the potential for expansion of passenger services. In time these will include the shuttles to the five-star hotels along the river and service for the increase to eight landing stations that will interface with the city’s growing sky train system.

“Since out mission is to provide enhanced services and ensure highest safety standards, out boats are therefore designed to include high-quality equipment and modern communications technology has been integrated into daily operations,” he noted

“This allows our passengers to experience a safe, professional and reliable transportation service. We will dedicate ourselves to constructively improving all aspects of our operations to achieve high efficiency and developing new services to accommodate emerging passengers’ needs, with a determination to become the leading boat transport company on the Chao Phraya River in the near future.”

The Chao Phraya River is one of the world’s most spectacular river passages

As each boat is finished, Sakun C owner and managing-director Khun Namchai Sakunchoknamchai has everyone involved in building it take a river cruise. This is not only a reward for the workers but it lets them experience the importance and the life of what they have built.

Alan Haig-Brown

Alan Roderick Haig-Brown is a Canadian novelist and non-fiction writer. He specialises in commercial marine and commercial fishing writing and photography. He is a regular contributor to a number of marine publications.