Business Case – Real Life Project Electric Propulsion Design and Installation on an Aventura 45 Catamaran

IntroductionAventura 45 Catamarans are built by the yard SGTI in Tunesia.

The yard had designed 2 versions: one version with classic thermic propulsion (Yanmar Diesel and Saildrive) and another version with electric propulsion.

The initial electric propulsion version was build around 2* 22 kW Electric engines from Oceanvolt, a Victron Lithium battery pack system and one heavy 20 kW generator from Fisher Panda.The electric propulsion was separate from the other systems on board.The system is based on a 48 V DC configuration.

Scoop of the Project

A new European buyer contacted us for advice and input regarding the purchase of a catamaran with electric propulsion. The Aventura 45 was on the shortlist.

After assessment, the client decided to follow our concept proposal and the yard agreed to work with us to complete the project.

The team of Yachtcommissioning performs the installation in the yard.

New Concept Design – Client specific.

Based on the philosophy of Yachtcommissioning, the concept of electric propulsion needs to meet the following 5 standards:

1.       Redundancy and Energy Management

2.       Limiting the number of inversions (DC/AC and AC/DC)

3.       Adaptable based on the use of the boat (day sailing/night passages/anchor/ocean passages)

4.       Communication

a.       System

b.       Local

c.       Remote

5.       Simplicity (autonomous)

Redundancy and Energy Management

With exception of special designed light weight boats with a lot of sailing power, a standard catamaran will always need a hybrid system, not only to feed the electric propulsion system but also other applications like appliances, air-conditioning systems, water makers, etcAs a result, a generator will always be needed.

In case you build in one powerful generator means you will have a relative high fuel consumption and there can also be a discussion regarding redundancy. When the generator fails, the situation can become dangerous certainly in bad weather conditions where you need full power.

Also installing one generator has an influence on the balance of the weight in the ship.

The concept Yachtcommissioning has developed is based on the use of 2 smaller generators (12-15 kW) in combination of 2 independent Power Distribution systems.

The energy management, which is fully software based, will consider the system as one big system and will start/stop the generators based on pre-configured settings which are determined during the sea-trials.Based on the use of the boat, those configurations may be modified remotely along the go.

Energy recuperation through the spinning of the propellors during sailing is possible depending on the yacht/catamaran type and the choice of the propellor. In this case, the Aventura 45, energy recuperation will be limited due to the lower average sailing speed compared to a sporty and fast catamaran (ex. Outremer, Gunboat etc)

Minimum number of inversions (DC/AC and AC/DC)

The concept is based on a 48V architecture. On the Aventura 45 there is a 12 Volt system for the classic navigation and safety equipment (bilge pumps, lights, winches and anchor)We would have preferred to have those systems on 24VDC instead of 12 VDC but that was nor possible.

Also, the client wanted a performing audio system which is based on 24 VDC supply.

There is also the standard 220 VAC network

During the concept development, we have designed the large users in the 48VDC system: 5 air-conditioning units with a central pump and one water maker which all will be 48 Volt.

For this concept, we have designed the set-up around components from Whisperpower. Whisperpower was the right partner to work with as they could provide a total solution.

Generators from Whisperpower are linked with Whisperpower DC Power Cubes (3* per generator) and are tested and matched with each other in the factory.The battery system are Whisperpower Lithium Power Plus rack systems which are pre-configured and pre-cabled which not only reduces installation time but guarantees maximum energy balance and reduces installation risks.

After the Whisperpower Power Cubes, all current is 48 VDC to feed the big consumers and the electric propulsion.The 220 VAC system is supplied by a 8 kW Inverter DC/ACThe 24 VDC system is supplied by 2* DC/DC transformers (48V to 24 V)The 12 Volt system is supplied by 2 additional 220 Ah AGM batteries which are charged by a 220V/12 V charger.

As a conclusion, all big consumers, including the propulsion are on 48 VDC, the smaller consumers on 12V, 24V and 220 Volt.

Adaptable based on the use of the boat

The electric propulsion system is delivered by Molabo. Molabo was chosen because of their technology developed in Germany and their motor efficiency. Also, the production in the facility of their mother company Hechinger was a major key decision maker as we knew the company already for many years to be a superior quality design and manufacturing company.In combination with adapted software designed by Whisperpower, both systems are talking to each-other.The Molabo engines which were chosen are the Aries 30 series which can be programmed between 22 kW and 30 kW.The propulsion train which is normally used by the yard STGI was redesigned to handle the bigger torque. The propulsion train consists of the use of an Aquadrive system.

In the energy management system, we can program all different settings like for instance the battery level when the generator starts, the reduction of power supply to the electric motors in case there is an anomaly.

Communication:

·         SYSTEM: The most important element in the design of the system was setting up the communication protocols between the powertrain and the power supply.

Whisperpower did some try-outs in the past to set-up a communication protocol between the Whisperpower software and the Molabo Software. As there were no projects at that time to integrate both systems, the project was put on hold.Molabo’s standard set-up is an electric propulsion using a Victron or Mastervolt battery energy management system in combination with a generator from Fisher Panda.

As we had the order of the project for the new Aventura 45, yachtcommissioning brought Whisperpower and Molabo back around the table.In collaboration, the Whisperpower software was adapted and re-written to communicate with the Molabo software.

·         LOCAL: The Whisperpower software will be linked and integrated into the MFD screens for easy user management and overview. Of course, additional specific screens for Molabo and Whisperpower will be installed. The Whisperpower software can be connected to most common brands like Raymarine, Garmin, B&G etc.

·         REMOTE: The entire system can be surveyed remotely at 3 different levels: - Customer Level: Through an app, the client can remotely survey the status of the system and change specific parameters- Installer/Dealer level: On top of the standard information the dealer/installer has the rights to survey the system at alarm and settings level. Also to follow up the history and use of the system- Whisperpower level: Highest level with full access to the history, alarm ad settings level.

This set-up allows to make a quick diagnoses and the ability to service the system remotely avoiding at the maximum level the intervention of a technician on short notice.

Simplicity

The entire set-up is focussed on simplicity towards the skipper and crew.

Based on the principle: “Keep it simple, stupid “the entire setup is to simplify the use of the boat by the owner.

The entire system set-up is quite complex but the use and the information to the user of the boat must remain clear and compact without giving to much unnecessary information.The system is surveyed remotely and in case there are anomalies, we will contact the skipper what to do or to correct.

Actual Status of the Project

At date of this status report, most components are installed and connected.

The yard is finishing the catamaran from their side until we come on board to finish the installation and to put the entire system into service.Sea-Trials and Commissioning the project is planned for the end of June, beginning July.

So please, bear with us and we will make a full report once the catamaran has been commissioned