Mochi Craft 23LR
The Mochi Craft 23 Long Range showcases the Ferretti Group’s talent for stylish design with a determination to rethink how efficient a cruising yacht can really be
There have been tentative moves towards greener technology in the motor yacht sector mainly focussed on more efficient systems or slower speeds. Ferretti has made a major step forward towards greener yachting with its Mochi Long Range 23 metre. Starting with a clean sheet of paper, the Ferretti design team has come up with a completely new concept of motor yacht that certainly meets the green requirements, but which is also aimed at a new market for the Ferretti Group – a long range cruising yacht or what many might term, a trawler yacht.
The Mochi Long Range is a two-part development that incorporates a new hull design married to a new hybrid propulsion system. The aim of the hull design has been to combine good seaworthiness with an efficient shape that allows good fuel economy. This can best be described as a trimaran hull, but the difference here is that above the waterline it looks like a normal sea-going monohull. The trimaran part of the hull only starts below the waterline and the aim has been to divide the hull into three long slim sections that reduce resistance, thereby increasing the efficiency of the hull.
The centre of the three hull sections is forward and is extended ahead by the use of a bulbous bow. This centre hull fades away just aft of amidships and it is replaced by two side hulls that extend for about half of the overall length so there is a considerable overlap between the centre and side hulls. The propellers are contained in the semi-tunnels formed towards the stern where the side hulls are deepest and the tail end of the centre hull terminates at the transom. This allows the propellers to be mounted within the depth of the hull so that there is security should the vessel ground. Ferretti has done considerable tank testing with this new hull design and reckon that there is a reduction is resistance of around 15 percent without any loss in the seakeeping characteristics of the hull.
This has resulted in a reduction in fuel use, but the propulsion system also aims to reduce both emissions and consumption. Ferretti has developed a hybrid system that allows the operator several options to power the vessel. One of the features of this new hybrid system is that the electric propulsion unit is an integral part of the installation and fits in between the conventional gearbox and the propeller. This 70 KW unit acts as both a motor and a generator, and there is a large bank of lithium ion batteries installed that Ferretti claims to be sufficient to power the motors for three hours.
The main engines are twin MAN diesels that each produce 800 horsepower, and these are enough to give the yacht a top speed close to 15 knots and a cruising speed of 12 knots. The diesels operate through a conventional V-drive gearbox and it is this gearbox that allows the diesels to be disconnected from the propeller shafts and for the electric motors to take over the propulsion. These two operating modes would probably be the main power sources, but the alternatives are to have the diesels and the electric motors running at the same time for propulsion or to have the motors acting as generators and charging the batteries from the diesel power. Alternatives for battery charging are from shore power or by using the two 35 KW generators that are on board – the Mochi Long Range 23 can be operated just by running the generators and the electric motors.
The control system for this installation is quite complex and is largely automatic, once the required operating mode is chosen. There are separate controls for use when the vessel is powered by the electric motors and there is adequate power from these motors for harbour manoeuvring. This means that the vessel can operate with zero emissions in harbour areas, while just using the electric motors, with the batteries being recharged from shore power when alongside. The electric motor propulsion can operate at any speed from zero to maximum, giving much more manoeuvring flexibility and it was a disappointment not to be able to test this feature as the yacht was still under development at review time.
The other benefit from the electric propulsion is the totally quiet operation that is available when operating under electric power only. This could be a bonus when operating in sensitive wildlife areas or for when the owner and guests simply want peace and quiet.