Yanmar Re-Power Reduces the Eco-Footprint


The Black Cat Group in New Zealand is an award winning eco-tourism company that is progressively repowering their fleet with Yanmar marine diesel engines. The latest vessel to be repowered is their flagship boat, Black Cat, which has been refitted with a pair of Yanmar 6HYM-WET commercial engines.

Black Cat

In the New Zealand eco-tourism industry, Black Cat is very much an international success story while also being recognised as New Zealand’s first eco-tourism operator. From a very modest start, the company now hosts more than 120,000 passengers on board one of their seven Black Cat vessels each year.


As a company committed to the environment, Black Cat has undertaken to reduce their energy consumption by 1% per year. According to Paul Milligan, Chief Executive Officer at Black Cat Cruises, the decision to re-power with Yanmar was heavily driven by environmental issues.


“We take our commitment to the environment very seriously,” said Paul Milligan.


“Our energy reduction program is a self imposed pledge where we undertake to keep our engines well maintained and modern by regularly introducing new engine technology into our fleet. With each re-power project, we strive for greater fuel efficiency and lower emissions.”

Black Cat1

To achieve their objectives, Black Cat Cruises has a strict “programmed re-power” strategy for their fleet of vessels. The repowering of Black Cat was four years in the planning, but just 4 weeks in execution.


During the low peak winter season, the hull was slipped at Lyttleton where a pair of Yanmar 6KY engines were removed. With some 15,000 hours logged over seven years, it was time to update the propulsion system with a pair of Yanmar 6HYM-WET engines. Rated at 650 mhp the Yanmar 6KY series has been superseded by the 700 mhp Yanmar 6HY-WET model.


“The decision to re-power with Yanmar was a heavily researched and considered selection,” Paul Milligan said. “Even though we had a great run with the Yanmar 6KY engines, we took our time and looked at all the various engine options that were available in the market. We needed to weigh up power, performance and the environmental issues of the latest technology across, all brands.”


“It wasn’t simply a matter of Yanmar out so Yanmar back in as a replacement. There are a lot of engines out there to select from. After we completed our research, Yanmar was a clear choice for us. Our other vessels are operating with Yanmar 6LY and Yanmar 4LH engines so we are very familiar and comfortable with the Yanmar brand.”


Yanmar’s 6HYM-WET model is a purpose built commercial grade marine engine. It includes Yanmar’s latest combustion chamber design, named ASSIGN, a system originally pioneered by Yanmar on their large bore, low speed propulsion engines.

Black Cat 2

This technology combined with Yanmar’s own mechanical fuel system delivers impressive fuel consumption results and provides commercial operators with excellent fuel savings.


The Yanmar 6HYM-WET is a 700hp twin turbo commercial model and is the perfect selection for those who require their engine to run at full throttle for extended periods. The cylinder head is a quad valve design. In this configuration, the Yanmar 6HYM-WET excels in conditions demanding continuous commercial use.

Much of the work undertaken on eco-cruises with dolphin watching cruises and dolphin swims, is carried out at an idle. However, when it is time to get back to the home port of Akaroa Harbour, the Black Cat skipper has absolute confidence in the Yanmar 6HYM-WET engines to lift this cat onto the plane and return to port on schedule at a comfortable speed.


Following the re-power, extensive sea trials confirmed the Yanmar as being the best engine of choice. At WOT the Yanmar 6HYM-WET engines driving through ZF 360 transmissions reached peak revs of 2200 RPM for a hull speed of 28.4 knots. A very comfortable cruise speed of 21 knots was achieved at an economical 1800 RPM.


During the peak season, the engines log up between 70 and 80 hours per week. The service interval on the Yanmar 6HYM-WET engines is a very generous 500 hours, which means that Black Cat Cruises can spend more time at sea and less time undergoing maintenance.


During the re-fit process, Black Cat also had a new MASE 2000T generator set installed. Powered by a Yanmar 4TNV engine, this MASE gen set is a 3 Phase model which is used to power the electrical equipment on board such as refrigerators, dishwashers, hot water, lighting and engines room fans.


Black Cat was built in 1993 by Sabre Marine in Perth, Australia. With a loa of 20m, a beam of 8m and displacement of 35 tonnes, this all-alloy vessel is licensed to carry 99 passengers.


Already, the next Black Cat repower project has been identified and locked into the program. This vessel is set to receive a pair of Yanmar 6LY3 engines which will be matched to the existing jet drive uni