Professional Skipper Magazine
Kauri Vessel Ready for Generations
“Internal access from this void through a watertight bulkhead door gives access to the spacious engineroom. This compartment contains the fuel tanks, batteries and the large Daewoo 158TA 540hp marine diesel engine. ”
“Cobalt attained a speed of 21 knots and a service speed of 18 knots at 1850rpm on her sea trials. During her stability checks, with 22 people on board, her maximum tilt was six degrees, indicating that she will be a stable vessel at rest, making her ideal for her intended role of day fishing trips.
Alan insisted on a fuel computer, because when you have a huge power plant and 540hp, if you want speed it takes a lot of fuel to feed these horses. The fuel computer is a good leveller and slows the hand up considerably, he says.
The Daewoo engine burns 7.5 litres per hour at eight knots. Working through the speed ratios, we converted the fuel consumption to the more realistic litres per nautical mile, and at eight knots Cobalt was burning one litre per mile. At 16-18 knots this leapt to four litres per mile, and at her top speed she was consuming five litres per mile. This definitely indicates that if you want speed you have to pay for it, an important consideration for the new generation of faster charterboats that are appearing on the Auckland waterfront.
Clearly, in this case, covering the miles quickly is not equal to distance travelled to fuel consumed. We would suggest that if many other fast vessels used fuel computers they would be surprised at the economies of fuel burn and costs.
The Daewoo is one grunty engine, and interestingly, when you buy a Daewoo marine diesel engine you not only get the engine and gauges but other boxes of fittings, which include valves, sea chest, strum boxes and a tool kit and other fittings.
On departing from the marina, we noted that as soon as the engine was engaged, the large propeller immediately bit, both when put into astern or ahead, and keeping the speed down in the marina was a bit of a challenge, as the vessel idles at five knots. While she is fitted with a mechanical trolling valve, this is not practicable when manoeuvring, as it is not designed for this purpose.
Although she ended up heavier than her original design expectations, the Cobalt’s wash when underway is more than acceptable and should not cause concern to other water users. Once underway, noise levels were an acceptable deep throb from within. As the Cobalt increased speed she maintained a nice angle with no noticeable high lift in the bow or burying of her tail. Equally, in the turns she maintained a stable aspect with no noticeably bad habits.
In closing, we found Cobalt to be a pleasure to be aboard. She is light, airy and comfortable. Even when underway, her spray from the chine rails is acceptable, and noise levels on board are very moderate at all speeds. To build a boat of this size and performance using timber and traditional construction is a love-hate affair, because you could probably build her cheaper using alloy or GRP. However, we are confident that this vessel will still be around in 50 year’s time, doing the sort of work she has been designed to do.
The choice of a Daewoo marine diesel is a step away from the expected traditional performance-versus-weight power plants. In saying this, the Daewoo is fast gaining a reputation as a strong, no-nonsense power plant that will deliver years of continual service.