5KW Brushless Sailboat Kit

$1,612.00
5KW SB
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Convert your 3-18 HP diesel engine to clean, quiet electric. Eliminate noxious diesel fumes and the frustration of filling up at the pump with the 5KW Brushless Kit featuring a Motenergy brushless motor and a 48V 275 Amp Sevcon Gen-4 Controller that can produce up to 5HP continuous and 14HP peak!  Enjoy your sailboat to the fullest, with a silent drive and truly fresh air.

This system is best for boats up to 6,000 pounds displacement. All our systems have reverse on-the-fly and contactor disable features. "Brushless" means that the motor does not have brushes that will wear out over time, nor will it be a dangerous source of ignition for on-board gas appliances. Larger boats may require a higher power AC or brushless motor. In the U.S. and Canada, brushed motors are only legal for marine use if onboard appliances and accessories use kerosene or diesel (not propane or gasoline) due to the potential for internal motor arcing.

With Sevcon's Gen4 controller, no reversing contactors are needed. Additionally, the Gen-4 controller has a regen feature than can allow current to be put back into the batteries from the spinning prop while under sail. This does depend on your sailing speed, prop design, and may not be possible in all applications, but is an adored feature for those who are able to utilize it.

gear reduction is not always necessary, and largely depends on the size, efficiency, prop style, and desired speed of your vessel. However, due to the high RPM of the Motenergy Brushless motor, we recommend you consider a gear reduction rather than direct-drive to improve efficiency, provide proper torque, cooling, and help prevent cavitation. Typical reduction is around 2:1, but this ratio will depend on the required prop RPM needed to reach hull speed. Ideal reduction will enable the motor to spin your prop at the hull speed RPM of your prop when the motor is spinning at its max RPM. This number can be calculated using the 50 RPM / Volt constant:

48 Volts * 50 RPM / Volt ~ 2400 rpm max

If you choose not to use a gear reduction, it's important to install a thrust bearing somewhere in line with the prop shaft, as most motors are not rated for axial/thrust loads on the shaft. Also note that a heatsink for the Sevcon controller is recommended by the manufacturer.

Kit Includes:

  • Upgraded Motenergy ME1305 Brushless Motor 
  • Controller: 48V Sevcon Gen-4 275Amp (can be set up to run at 36V), programmable, with regen
  • Throttle (additional cost)- your choice of: 
    • PB-8 throttle and Fwd/Rev switch 
    • ET-134 directional throttle. For harsh environments we recommend the ET-134 as the most robust option. 
  • Tyco High-Quality Sealed Contactor
  • Key Switch
  • Fuse
  • Every kit is individually bench tested
  • Complete wire harness with 10ft key and throttle cable lengths
  • Wiring instructions

Helpful Links:

Check out our instructional wiring video!

You may also be interested in the Sevcon Clearview display!

Those of you that are still in the "research phase" of your conversion should visit one of the electric boats discussion groups and talk to others who are doing or have already done electric conversions.

Gen4 5KW Sailboat Kit Wiring Diagram - for Curtis ET Throttles

Gen4 Sailboat Kit Installation Instructions

E-Boat Modeling Spreadsheet (.xls) *Use this to calculate your power needs!*

E-Boat Modeling Spreadsheet Manual (.doc)

Vicprop Calculator

Hola, que kit es necesario para mi barco a vela,eslora 6,5 peso 2.000kg
Hola! Utilice el kit de 5kw con una reducción de engranajes de 2: 1
Sí, el kit de 5Kw con reducción de 2: 1 funcionará. Envíenos por correo electrónico por favor con la marca y el modelo del barco.
Wanted to share my successes and learnings with the 5kw Thunderstruck kit, using the Sevcon GEN4/size 4 control and the ME1305 motor.

I replaced what appears to be the original 2.5hp GE/Taylor Dunn 36V series wound brushed motor. This motor achieved 5.5mph at 2kw turning 3000RPM, with v-belt reduction 3:1 driving an eight inch three blade composite propeller. The motor compartment is small and mounted high under the captain's seat midship, and is unventilated. The motor easily reached 180F underway for an hour and smelled like insulation and ozone. The speed control was a Salzer four three pole four position (+ off) that switched the battery configuration between 6S1P 36V to 3S2P 18V.

I expanded the battery bank to 48V with two additional 6V batteries, so the total capacity is about 10.5kwh, and is measured with a Bayrite chinesium watthour meter.

The new ME1305 was installed in a custom aluminum box that supports the NEMA C 143T size motor, with ducted cooling to the inlet side of the motor. The ducts pull air from an aluminum heatsink enclosure that the Sevcon controller is mounted to.

Testing on the Vermilion bayou was a little tricky due to river current, but to achieve the same propeller revolutions the motor and controller required 1200W watts to reach 3000RPM, so using 40% less energy than before. This, combined with less amperage at 48V brought my underway discharge rate from 55A to 25A, a major Peukert win. I went from 85MPGe to 131MPGe (2.5mi/kwh to 3.9mi/kwh), not accounting for any Peukert gains.

Despite having twice the available HP, I can't really increase my speed. My target was to put the ME1305 at its peak efficiency range of 3000-3500RPM, and the motor performance curve falls off quickly at the upper end of this speed range, so WOT gets me 3625RPM at 32A (1.5kW), which looks like about 6mph. At 70F ambient, the controller makes no apparent heat, and the motor skin reaches 90F after several hours and 18 miles of river travel.

Very happy with the kit build quality and value. My only suggestions would be for them to mark CW/CCW on the ET134 directional control, and smaller ring terminals for the Sevcon end of the cables.

Next modification will be propeller optimization.
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