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Aus-Thai's AT47 Monohull
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Aus-Thai's AT47 Monohull Aus-Thai's AT47 Monohull Nestled amongst the glamorous (and comparatively expensive) yachts on offer at the Ocean Marina Boat Show was what, at first glance, may have appeared to be an ugly duckling. But first appearances can often be deceiving, and such was the case with the Austhai AT47 Monohull that Austhai Marine exhibited at the show. The vessel intrigued us for a number of reasons, the principal one being that the production of a monohull is a significant departure from Austhai's normal operation, which, until now has been exclusively catamarans. So we approached Ray Ringuet, the Managing Director of Austhai Marine for a chat.
Why the change to Monohulls?

Two years ago we were involved with the Boat and Yacht Thailand Seminar, the focus of which was safe boating in Thailand, especially in relation to water-based tourism. As I think we all acknowledge, in Thailand, there are far too many boating accidents, often involving fatalities, and most of these are associated with the tourism industry. At that seminar, in conjunction with our consulting naval architects, Albatross Marine Design, we presented a paper which dealt with the design parameters of a safe monohull. Unfortunately, over the ensuing 12 months we saw no significant improvement in the design or construction of tourism boats, so we decided that having talked the talk we should walk the walk and hope that others will follow.

What processes did you follow in bringing the project to completion?

Firstly, over the past ten years we have gained a fairly intimate knowledge of the operations of water borne tourism operations in Thailand and Asia generally. There is a significant trend to larger boats carrying more passengers, primarily based on the economics of scale. There are also operational restrictions, such as the necessity in many cases to beach load. So our first step was to document the knowledge that we already had and then develop the most economical size, based on the number of passengers, power requirements, fuel efficiency, capital investment required, etc. We gave all of this information to Dr Albert Nazarov of Albatross Marine Design and said "Here is a challenge for you?"

Aus-Thai's AT47 Monohull
Aus-Thai's AT47 Monohull
Aus-Thai's AT47 Monohull And what was the result? Did you get what you wanted?

We thought the challenge we gave to Albert was perhaps over optimistic, but he proved us wrong. He has managed to design in all of the parameters that we gave to him. The requirement was for a boat to carry 50 people, to be powered by inboard diesels or outboard gasoline engines, to achieve a minimum cruising speed with outboards of 30 knots, and 25 knots with diesels.

It had to be seaworthy, comfortable, meet the applicable ISO Small Craft Safety regulations. In addition, it had to be almost unsinkable. Finally, based on a number of criteria, it had to provide a suitable return to a commercial purchaser. His design achieved each of the goals we set for the project.

What differentiates the boat from the traditional speedboats servicing the tourism industry?

Perhaps, the most important fact is that it is designed to meet ISO Small Craft Regulations. This involves issues such as structural strength, stability, fuel systems, electrical systems, safety, etc. Unfortunately, very few monohulls operating in the tourism industry in Thailand meet these standards.

Aus-Thai's AT47 Monohull
Aus-Thai's AT47 Monohull
From a practical viewpoint it is wider, with a uniquely designed hull form with multiple chines that allows it to get up on the plane quickly and operate economically, while at the same time providing a smooth, safe ride for passenger comfort.

Because of the wider beam, it is able to carry up to 51 passengers and 5 crew, all in forward facing seats, which, of course, are safer and also more comfortable than the traditional side seating found in most speedboats. It also has bow seating for use when the boat is moored for sunbathing, etc. It has much wider boarding platforms aft than traditional Thai boats, which makes boarding and disembarking much safer and more convenient.

It is also virtually unsinkable. Of course, no boat is unsinkable, but this boat has two watertight bulkheads forward and ten watertight compartments under the floor. These watertight compartments are in the form of a matrix which provide for a supremely strong and rigid hull. Even if a number of these compartments are breached the boat will still float.

The boat is built with a sandwich construction using Nidacore and Diab foam, which has significantly reduced the weight while providing an exceptionally strong and rigid structure. The low structure weight means a higher passenger capacity and great fuel economy.

The other challenge that we gave to Albert was to maintain the traditional Thai styling. This he achieved but he also gave us a hardtop version for those who want to have that little extra passenger comfort.

The crucial question of course is performance. How does the boat perform?

We currently have two boats in the water, one powered by triple 250 HP outboards and the other by twin 315 HP Yanmar with Yanmar ZT370 stern drives. Both have exceeded our expectations. The maneuverability is excellent, the ride soft and true, and both boats are dry. The outer chines deflect the spray away from the boat.

Testing has been very interesting. The twin Yanmars produce a top speed of 28 knots with full fuel (700 litres), full water and with ten people on board. With a full load of 45 passengers and five crew the speed drops by only two knots. This is a testament to the architect's hull design. The outboard-powered boat has a top speed of 38 knots and will cruise very comfortably at 30+ knots.

Performance must be measured in terms of return on investment. This depends on the durability of the boat, the operating costs, etc. We are confident, based on the assessments that we have done, that our architects have also given us a design that fulfills this criteria.

So overall you are satisfied that the decision to embark on this project was the right one?

Emphatically. We believe it is a win-win situation. The operator gets a better and safer boat with a greater rate of return; greater passenger capacity means a more economical operation, whilst the comfort and safety issues will make this boat more appealing to tour operators. The tourist gets a more comfortable ride and a safer trip. Thailand will over time get a better reputation for boating safety. All round win-win, so a very satisfactory outcome.