There are two primary designs of hybrid systems available for yachts – Serial or Parallel. After much research, we chose to use a Parallel Hybrid model. There are many reasons for this decision, which are explained in detail below.
Hybrid Design Overview
Critical Design Requirements
We developed a solution that does not deviate from our history of never compromising crew safety and comfort for the latest market trends and newest technologies. Our boats are designed to be dependable, redundant, and safe in extreme weather conditions and remote locations. In addition, keeping customer needs in focus as we modify our offerings is one of the reasons we are ‘The Worlds’ Best Liveaboard.’
We feel it is essential for our customers to understand how we arrived at our Hybrid offering. Here is our table of critical design considerations.
Hybrid Designs Overview
There are two primary types of hybrid systems for yachts – Serial & Parallel. Parallel systems exist in either External or Flywheel versions.
This is an example of a Series Hybrid system from OceanVolt. These systems rely on a DC generator to charge the batteries and power the two electric motors which in turn power the Yanmar sail drives.
There are a number of reasons why this system was not selected by Antares:
- We will never put a sail drive on our boats
- Serial hybrid systems are less efficient than parallel systems
- OceanVolt batteries are not LiFePO4 chemistry (more on this here)
A Flywheel Parallel system uses a traditional diesel engine, in a series with an electric motor and transmission to power either a salldrive or shaft. This is an example of a Volvo design currently in development with Fontaine Pajot.
We did not select this type of Parallel system for the following reasons:
- The space required is too ‘long’ in length to easily fit in the Antares GT
- If the clutch fails, the engine and motor are disabled
- This design is less efficient than the external parallel design
An External Parallel system uses a traditional diesel engine. The motor/generator is kept out of the conventional drive chain and connects to the driveshaft after the gearbox. If stand-alone generation is needed a clutch is required to disconnect the propeller shaft. If the clutch fails, it can be manually engaged, providing additional redundancy.
We are pleased to be partnering with Hybrid Marine for the Antares Hybrid. Graeme (CEO) and his team have been outstanding in their support of our project. We share similar values, and the leadership and expertise Hybrid Marine brings to Antares are over fourteen years in this marine hybrid business. The technology is proven, easily serviced, and redundant.
- The best overall solution that meets our criteria
- 14 years of parallel hybrid experience in the marine industry
- Yanmar UK in partnership with Hybrid Marine (same engine we use on new GT)
- Member of ISHY (Implementation of Ship HYbridisation) since 2019
Another advantage of a hybrid, is the ability for the electric motor to serve a dual purpose and generate power. As the boat is sailing, you can generate power to top up the Lithium batteries and power your onboard appliances.
For comparison, the power curves for the Hybrid Marine system we are using is very similar to the Watt & Sea 600 hydro generators. The power curves are below.
Power Consumption Scenarios
We must answer the ultimate question, ‘So What?‘ How does the NEW Antares Hybrid affect daily life aboard the boat? What do the power consumption scenarios look like, and why does this matter?
The following consumption scenarios are based on real-world numbers provided by Antares owners. The solar generation numbers are based on a 30-day test in tropical conditions with Panasonic HIT panels aboard s/v Field Trip. We have done our best to provide realistic numbers. However, every boat owner is different, so the numbers will vary from owner to owner.
All appliances and cooking are assumed to be electric, with no LPG onboard.
The conservative model provides plenty of excess power regardless of the cruising season. 1,800 watts of solar power is sufficient to live comfortably, while completely independent of fossil fuels.
The 40 kWh of Victron Lithium allows for luxurious living. This scenario has either the port or starboard aft cabin running the AC for four hours every day AND making hot water for showers and washing dishes. This gives the owner anywhere from 1.5 – 3 weeks of luxury, without ever needing to start an engine to recharge the batteries.
Using a combination of the two models, it is possible to still run the AC periodically, heat the water, and still have a neutral carbon footprint.
Passagemaking consists of about 10% of the total time living aboard an Antares. This 10% is when you may need to use the electric motors to leave an anchorage or marina. When underway, averaging seven knots, the daily surplus of power (10kW – 11kW) is plenty of power to not only recharge the 40kWh of Victron Lithium but run A/C and any other devices on board.
This is a complex topic. To put it simply, Antares will only use LiFePO4 (Lithium Iron Phosphate) batteries in our boats. The reason is simple. LiFePO4 is the most stable chemistry and far less prone to issues like fire. There is a reason why Victron and Mastervolt are ONLY using this chemistry for their marine batteries.
Other battery chemistries used by electric vehicle (EV) manufacturers are more efficient and have higher energy densities. At present, we don’t believe this technology is ready for the marine environment. A fire in a car on land is tragic and potentially life-threatening. A fire aboard a boat 1,000NM from land or in a remote atoll is an entirely different matter.
Sometimes, several pictures and some recent data are all that is needed to put this topic to rest.