Electric Boat Propulsion Systems
What should boat builders look for when going electric?
Sustainable boating is officially the way of the future, and forward-thinking boat builders are making sure to move to electric boats now to stay ahead of the competition and gain an advantage. In order to obtain a significant share however, you must choose the electric boat propulsion system that will give you the greatest competitive edge. Unfortunately, choosing which electric propulsion system to employ can be overwhelming given the amount of options available. So in this article we outline what you should look for when comparing electric boat propulsion systems so you can be sure the investment in your new electric tender or RIB range pays off.
We’ve written this article for boat builders looking to produce an electric tender or RIB around 3-5m in length and targeting customers wanting to use with their motherships for short trips to and from the shore, to explore surrounding locations, or for watersports, fishing, and swimming. Based on this size, the electric boat would be stored in a tender garage onboard the mothership, or hung on davits on the back of a cruiser boat.
The electric opportunity- why move to building electric boats?
What to look for in an electric boat propulsion system for an electric tender or RIB
Choosing an electric propulsion system for your electric tender or RIB
The electric opportunity- why move to building electric boats?
As a result of clear environmental concerns, political pressure, and compelling options, consumer demand for electric boats is booming. While it is estimated that electric boats represent just 2% of the recreational watercraft market today, the global electric boat market is projected to reach a whopping $16.6 billion by 2031.
And thanks to the lucrative opportunity, advancements in electric propulsion technology mean that boat builders no longer need to compromise on practicality or performance in order to go electric. In particular, inboard boat propulsion technology has experienced significant innovation, so builders can now achieve higher margins by selling world-class boats as a whole package to their customer or through their dealer network.
Boat buyers won’t settle for any electric boat however- they have high expectations and are willing to pay a premium for the electric boat that requires the least compromise. The zero compromise boating revolution has indeed begun.
What to look for in an electric boat propulsion system for an electric tender or RIB
Performance
Here’s what to look for in an electric propulsion system to produce a high-performing electric boat that boasts easy maneuverability, speed, fast acceleration and efficiency:
Direct drive systems: If your electric boat is powered with a direct drive system, it will respond faster to throttle changes, suffer fewer energy losses and have a lower center of gravity than one containing a gearbox.
Jet propulsion: Boats powered by electric jet systems experience less drag than outboard motor boats as they do not have any parts protruding below the hull. They can be more efficient as the high jet exit velocity generates more thrust the faster they travel, unlike electric outboards which can encounter resistance at higher speeds due to their propellers and drive legs. For a detailed comparison of electric boat motors please see our guide Electric jet boat motors or electric outboard motor- which is best?
Inboard configuration: Unlike outboard motors which have their engines mounted on the transom of an electric boat, inboard boat motors give an electric boat a more centralised weight and a lower center of gravity. This results in more on-board space and often easier handling
Lightweight: With less mass to accelerate and maintain in motion, boats powered by lightweight electric propulsion systems will consume less power and experience a reduced moment of inertia, allowing it to accelerate quicker and reach higher speeds. The world-leading jet unit by ZeroJet for example, weighs 40 kg excluding battery packs (and does this without compromising power).
Right power output for your target boat size and weight: an electric boat propulsion system with insufficient power for the size of the boat may lead to difficulty reaching desired speeds and getting up onto the plane. An electric boat weighing roughly 150 kg total and carrying an average of 2 passengers will need approximately 15 kW of power (20 hp equivalent).
Range and runtime: For the intended use outlined above, your electric boats should offer around 40-50 minutes runtime & 10 nautical miles range so customers experience less range anxiety when using your boat out on the water.
Efficiency at both low and high speeds: This will ensure your boat offers the best mix of range at high speeds (especially helpful during time-sensitive trips) and runtime at low speeds (especially helpful in speed restricted areas or during leisurely cruising).
Safety
Here’s what to look for in an electric propulsion system to help you produce safe electric tenders or RIBs for your customers:
Low voltage system: Voltage is a key determinant of safety on an electric boat as one that is too high increases the risk of electrical shocks or burns. The most advanced electric propulsion system can be low voltage without compromising performance. For example, ZeroJet designed a world-leading 48 V system that is able to deliver a high amount of power despite its modest voltage.
Safe batteries: LiFePO4 batteries are the superior electric boat battery as they are safer due to a very low risk of thermal runaway. They are also far less likely to ignite under extreme conditions, even if damaged or punctured.
Sophisticated Battery Management System (BMS): Look for one that prevents excessive current draw, and monitors and maintains safe battery temperature, current and throttle input.
Reliability
Here’s what you’ll want to look for in an electric propulsion system to deliver an electric boat your customers can rely on:
A minimum IP rating of IP64: The higher the IP rating, the better. The electric boat propulsion system’s IP rating is dictated by the international IP standard. This standard indicates the level of protection against water, dust, accidental contact, and intrusion and the electric boat propulsion system's overall ability to withstand the harsh marine environment.
Protective battery cases: Look for waterproof and impact-resistant cases that protect the battery packs from the elements and accidental damage.
Few moving parts: Less moving parts mean less components to fault:
Direct drive system: These don’t contain transmission components, such as gears, pulleys or chains.
Electric jet boat systems: Unlike electric outboards, they do not require a drive leg, propeller, power unit or enclosed electrical components exposed to the elements on the transom.
Brushless DC motors: Compared to brushed motors, they have no mechanical brushes that wear out and which can generate heat during operation. They can last tens of thousands of hours.
Support to design and integrate
Here’s what to expect from an electric boat propulsion system supplier to ensure that you can achieve your vision and avoid compatibility issues and performance limitations:
System options: An electric boat propulsion system should offer system placement or configuration options as well as battery pack options (in different kWh) for achieving different range and runtimes. For example, the ZeroJet Gen2 electric jet boat systems offers both 5 kWh and 10 kWh battery packs with a number of different system configurations.
Help in determining technical feasibility: To help assess compatibility with your boat design, hull type, propulsion arrangement, and other onboard systems.
Engineering support: Throughout your design, prototyping and testing stages, including supplying 3D files and a prototype based on your design.
Minimal modifications needed: A compact electric boat propulsion system with few moving parts requires less modification to hull design and internal compartments.
To discuss the systems we offer and determine the technical feasibility of the ZeroJet Gen2 system for your electric range, book a consultation with the ZeroJet team.
Easy to install
Here’s what to look for in an electric boat propulsion system to ensure the production efficiency of your new electric boat range:
Plug and play system: The electric boat propulsion system should start working when first connected, without reconfigurations. For example, one that has a waterproof housing containing mounting hardware and running gear in one unit.
Technical support and training: Technical support and training for easy troubleshooting during installation and commissioning.
After-sales service
Here’s what to look for in an electric boat propulsion supplier’s after-sales service to ensure that your customers have a positive experience:
A minimum 2-year warranty: Based on recreational use and on both the electric system and batteries.
Accessible after-market repairs: For both in-warranty and out-of-warranty repairs. Service agents should be available in major locations that you have customers or distribution to.
Easily available spare parts: Easily available over the entire expected lifetime of boat ownership with access to repairs and replacements.
Choosing an electric propulsion system for your electric tender or RIB
So as a boat builder, how do you choose a system when you want to electrify your tender or RIB range? Electric boat propulsion systems will vary in their appeal, and ultimately selecting the right system depends on your specific design and build requirements and the significance you assign to each criteria we have covered in this article.
Book a consultation with the ZeroJet team if you’d like to discuss electric system options.