Case StudyNB Chelonian


NB Chelonian is a 60ft Semi Trad built in 1994. In 2007 Chelonian was re-engined with a Beta 43 Hybrid system and partially refitted to install a 450Ahr battery with new domestic appliances to go gas free. The boat has been in regular use since 2008 and used its original battery until 2021 when it was upgraded to Lithium batteries.

Chelonian featured in Canal Boat June 2009 "How a Hybrid Works"

The system shown in this article was fitted to Chelonian in 2007 and the Lead acid batteries shown were fitted in 2008. In 2019 these batteries were sent back to the manufacturer to do a capacity test which showed that after 11years they still retained almost 80% of their original capacity. The batteries have been refitted to Chelonian and are expected to give several more years service before they need to be replaced.

Customer Requirements

My requirements for a electric/hybrid drive were as follows.

1. provide the same range and power as a conventional diesel system.

2. allow silent electric propulsion for extended periods (hours)

3. allow a practical mix of diesel/electric drive without extended battery recovery time.

4. allow the propulsion batteries to be utilized to provide domestic electrical power.

The hybrid marine solution fulfils all of these requirements. Using the parallel hybrid design allows the full power and extended range of the diesel engine to be used without compromise allowing sufficient power for river and tidal crossings, and the extended cruising range (200 hours) to be maintained. In addition the electric drive can be used when appropriate to provide extended silent cruising or around 4 hours, or more if lock passage included. The use of the propulsion motor as a generator when using diesel propulsion allows a quick recharge of the batteries with approximately a 50/50 diesel/electric duty cycle. this means that using the electric drive is a regular daily part of the days operation rather than a special event.

The use of a standard 48v battery plant means that standard off the shelf inverter/ charger systems designed for marine use are available at reasonable cost (Victron Multiplus 48/30). The capability of these units to provide high power outputs in parallel mode (10kw +) makes it practical to replace the gas cooking appliances with electric hobs and ovens, improving safety and usability. This has been a major improvement to the services on board as in common with most canal boats using "leisure" batteries for domestic electrical power the systems are almost always under powered and careful management of the available electrical power is needed to avoid exhausting the batteries on a daily basis. Also the regular deep discharging of "leisure" batteries means a short life before significant loss of capacity with regular replacement every three years or so. The use of deep discharge traction cells has also meant that the system is now in it's 3rd year of operation with no significant loss of battery capacity and worrying about running out of domestic electrical power is a thing of the past. In addition the large capacity 230v system allows the inclusion of a washer dryer on board, a major benefit on a wet cold windy day ! Other electrical appliances that would not be contemplated on a conventional boat include an electric kettle, a bread maker and toaster all improving the convenience and usability of the boat.

In addition to meeting the original requirements the system also provides a number of additional benefits. The system has shown a dramatic saving in fuel overall with the predicted consumption per hour when using the diesel for propulsion and electrical charging being typical of a conventional boat using the same engine (i.e. no increase in fuel consumption to recharge the batteries) using electric propulsion for around 50% of the cruising time, and virtually eliminating the need to run the engine solely for battery charging has meant that the boat uses significantly less than half the diesel fuel of an equivalent conventional boat. In addition the replacement of the gas cooking with electricity further reduces the operating costs and carbon emissions. Additionally the reduced engine hours result in savings in servicing costs.

The use of electric propulsion results in a whole new experience of cruising, reducing the impact on the environment from noise and vibration. It is noticeable that you get to hear all the sounds of the countryside such as the birds singing that are usually drowned out by the engine. It is also noticed that the canal side wildlife such as herons and kingfishers can be approached much closer when on electric drive. The silent electric drive also has safety and operational benefits, particularly when manoeuvring and operating locks as the person on the helm can now communicate verbally with the crew elsewhere on the boat and on the ground, something which is rarely possible even shouting when standing on top of an idling diesel engine.

The large capacity propulsion battery also means that extended "off net" stays on the bank are possible without needing to resort to extended operation of the Diesel for battery charging. A fully charged battery on Chelonian allows up to 4 days of domestic use including cooking using approximately 4Kwh per day. If necessary an hours operation of the diesel in charging mode will provide enough power for a days domestic consumption. Before the hybrid conversion it would be necessary to run the diesel for approximately 4 hours a day to charge the domestic batteries for a nights power. Using approximately 6 litres of diesel (approx. 60kwh) to generate around 1.5Kwh of stored electrical energy, a horribly inefficient way to obtain electrical energy.

In many places canal side electrical points are becoming available, for instance at some Thames locks, popular destination (e.g. Llangollen canal terminus) and at most marinas. Charges for these vary from around 15p a unit to around £5 per day often included in an overnight mooring charge. By managing the battery state to arrive at these locations with a discharged battery it is possible to make very effective use of mains power for propulsion. A fully charged battery will provide in excess of 4 hours cruising replacing Around 6L of fuel at a cost of around £6. A full charge consumes around 20Kwh or £3 of electricity.

Dave McInerney. Canal Boat Chelonian

System Details

Engine:  Beta 43
Hybrid System: Single electric motor
Battery: 450Ahr @ 48v Flooded Lead Acid Traction Cells with common watering and gas venting system. 3-4hrs Electric Drive Autonomy
Electrical System: Dual Victron Energy Multiplus 48/3000/35 - 70A DC charging and 6Kw AC Power
Monitoring: Victron BMV602 and Colour Controller GX

NB Chelonian is fitted with the Hybrid Marine Standard Inland Waterways Narrow boat (single Electric motor) package with a 450Ahr battery allowing 3-4hrs of Electric Drive Autonomy and sufficient 230v domestic capacity to go gas free. The Galley has a conventional domestic Oven, Induction hob and kettle, plus an assortment of other appliances such as a bread maker, toaster, coffee machine. A domestic washer dryer is also fitted and can be run from the Inverters and Battery without the need to run the engine.
Battery monitoring is by a Victron BMV 602 which provides a "fuel gauge" for the battery, this is connected to a Victron Color Control GX providing an overview of the electric systems, and allows remote monitoring over wifi or mobile data.