Bear Mountain 30 Hybrid Electric Launch
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Bear Mountain¹s most recent project is a 30' hybrid electric/diesel/solar fantail
launch.
Visually reminiscent of the fantail steam launches used in our area a
hundred years ago, it brings to mind an era when taking a journey was
as enjoyable as arriving at the destination.
This low impact, eco friendly cruiser will accommodate a couple in simple
yet luxurious comfort and safety during an inland voyage of several weeks.
The easily accessible aft lounge provides seating for 6-8 guests on day
trips to picnic, bird watch or fish.
To meet our objective of consuming the least possible amount of fossil fuel,
Canadian yacht designer Steve Killing has created a hull shape that is optimized
for low speed cruising.
Jonathan Killing has designed the hybrid electric/diesel/solar propulsion
system. It will provide multiple power options in an efficient, integrated
system to drive the boat with an electric motor directly connected to
the drive shaft.
General Description
The Bear Mountain Hybrid 30 is designed for low speed cruising on inland waterways. Up
to six passengers can comfortably enjoy day trips with seating in the open aft area. For
longer trips, an enclosed galley, head, and cabin can accommodate two people.
Eight solar modules charge the battery pack to full capacity between trips. With sunny
weather, the pack should recover from 80% charge within 2 days.
When underway, a user interface (see Figure 1) shows the operator the current status of all
of the components including power flows and state-of-charge. A simple, intuitive screen
allows the operator to see which sources are supplying power and adjust speed to suit the
desired balance. For example, for purely solar boating, the operator can match the motor
power to the solar input and maintain the battery state-of-charge.
Figure 1 - The user interface will provide touch-screen access to information
about the current state of the vessel (power flows are for illustration
only)
Performance
The boat’s top speed will be around 6 knots because the efficiency of the hull shape drops
off steeply around this speed. At 6 knots, the motor must deliver 3kW of thrust which can
be delivered for 1.2 hours from the batteries alone. If a longer run time is desired, then the
generator will automatically engage and supplement the power. Since the generator power
exceeds the required motor power, the batteries will charge during this period.
At lower speeds, the boat requires less power and much longer run times are possible (see
Figure 2).
Figure 2 - Predicted vessel run times as a function of running speed
System Description
The basic layout of the power system is as shown in Figure 3.
Solar Modules provide continuous power to the batteries when the vessel is at rest and help
to offset the load when in motion.
Diesel Generator engages when the control system detects the need for increased power or
when a low battery condition exists. The generator provides the full 3kW load required to
drive the boat at top speed with excess power going to charge the batteries.
Electric Motor provides propulsion through a direct drive shaft to the propeller. Though the
motor is rated for 5kW, the maximum theoretical drive power is only 3kW at top speed
(including mechanical and electrical losses).
Battery Pack can be charged by the solar modules, diesel generator, or shore power. Total
capacity is 360Ah contained in 16 AGM batteries. Usable capacity is 20% (72Ah) to maintain
battery life.
Auxiliary Loads (not shown) include inverter to provide 120VAC, bow thruster, and 12V
loads such as lights and navigation equipment.
Figure 3 – Proposed Power System Layout (Minimum Power Values Shown)
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