Electroprop Powertrains


We offer 7 different Powertrains from 5 to 21 KW continuous with DC and AC Hybrid Options.  Please see renderings below on this page.

Each Powertrain includes every component for all your energy needs aboard sailing vessels up to 42,000 lbs. displacement.

Each Powertrain is component based and is designed to be intuitive to operate with Graphical User Interface that keeps you completely informed with complete information on the motor, controller and battery bank.

Safety, Efficiency, and High Thrust make our Drivelines Reliable and Strong with Very Low Maintenance and Cost of Ownership.


Component Description


Smartplug Shorepower Cord with Integral GFCI protection.    We custom make our shorepower cords by molding in a GFCI Breaker within 18 inches of the shorepower pedestal.    The GFCI protected cord protects the entire boat from Ground Faults and eliminates the possibility of Electric Shock Drowning in fresh water and Corrosion in Salt Water.    Shorepower cords that inadvertently end up in the water, while casting off, are protected.


Smartplug Inlet.    Smartplug Shorepower Inlets have large electrical contact areas and are O ring Sealed for Safety and Corrosion.    Smartplug keeps improving their product line and now has unique high strength wire connection points inside the boat for improved safety.   Large contact areas and better connections are better suited for charging large banks of batteries found on Electric Boats


North Shore Inline GFCI protection after the shorepower inlet.    A second, whole boat, Shorepower breaker is mandated by law between the inlet and the isolation transformer.    By having this breaker inline it takes up  less space, is water proof, plus provides for redundant whole boat GFCI protection for reasons stated above.


30 amp Charles Isolation Transformer.   The Isolation Transformer is the only way to protect a boat from an Electric Shock Drowning event.    Without an isolation transformer all grounds are continuous or uninterrupted.     The Isolation transformer separates the grounds, line voltage, and neutral current carrying conductors on the boat from the ground, line voltage and neutral on the shore.    The Isolation transformer prevents Corrosion in Salt Water.   Electricity always returns to the source of power.   The Isolation transformer becomes a new source of power so any electricity on board the boat returns to the Isolation Transformer on the boat and will not attempt to return to the last shore mounted transformer.

Because the source of electricity has been re-derived on the boat, there is no nuisance tripping of the GFCI breakers on a boat equipped with an isolation transformer.    A Transformer based (not high frequency)  isolation transformer will not leak any current to ground, which allows full boat, reliable, GFCI coverage at the 5 milliamp threshold.

The Isolation Transformer is connected to boost the AC voltage from 120 volts to 240 Volts Split Phase for the Charging System.    All high frequency chargers are current limited on their input.    Boosting the voltage from 120 to 240 allows most high frequency chargers to charge up to 80 Percent faster.      Additional outlets on the boat are still wired at 120 volts, and only the charger sees the higher voltage.

The Isolation Transformer serves to clean the power from other voltages that are superimposed on all Shorepower.    Its an interesting point, that many people don’t know, but shorepower can have a host of different voltages and waveforms on it at any one time, in either AC or DC.    The Isolation Transformer serves to smooth out any surges and eliminate most superimposed AC voltages and DC voltages and get a smooth, consistent AC wave form for the charger and any other electronic equipment on the boat.


Electroprop Waterproof AC distribution with every circuit protected by a double pole breaker.    Additional GFCI protected AC circuits are available for 120 Volts Appliances aboard the boat.    The AC distribution panel can be eliminated if the owner does not need additional AC circuits.


Electroprop 3 KW, Dual Voltage,  Waterproof, Insulated Charger System.    Charging systems with non-metallic cases do not require bonding of the charger to both the AC ground and to the Battery Negative.    Metal Cased chargers therefore lose isolation of the battery bank.    Isolation of the battery bank is necessary to be able to monitor the battery bank for ground faults.

The Electroprop Charger has three modules which can be either 12, 24 or 48 volts.    Our standard charger comes with two 48 volt modules and one 12 volt module.    The charger is wired to run 2 of the 3 modules at any one time.       The charger will charge the batteries or provide AC hybrid operation at 50 amps at 58 volts, with a 100 amp x 12 volt accessory charger for the house battery.  This is one powerful Charger!

The Charger Modules are encapsulated in Aluminum which is attached to a heat sink which is mounted through the back of the charger box.   The charger box is then mounted on Electroprop’s Forced Air Cooling Box to cool the heat sink which pulls the heat out of the charger modules.   The heatsink with Forced Air Cooling Box allows for Waterproof construction of the charger box.

The Water proof construction is enabled by very high efficiency charger modules so less heat is required to be evacuated from the sealed box.   Charger Efficiency is as high as 92%.

Each module gets power through a dedicated high current relay controlled by Electroprop’s Lead Acid Battery Management System.

Charger Surge Protection is mounted inside the Charger’s Waterproof Box.

The Electroprop Charger has full current output at Absorption Charging Voltages.


Electroprop 6 KW Charger:   

All the same as the 3 KW charger but utilizing larger components in a larger enclosure.


DEHN Surge Protection

Shorepower surges are common and can be harmful to any kind of electronics so its best to protect them.     The Isolation Transformer serves to smooth out most shorepower issues while providing necessary isolation.    The Electroprop Charger is further protected by a Surge Suppression Device.    If the surge comes from the shorepower, it is diverted into the grounds, thus protecting the charger modules.   If the Surge comes from lightning through the grounds, it allows the line voltage to rise with the ground voltage to prevent excessive voltage differentials within the charger, again protecting the charger modules.     We also provide optional whole boat surge protection if your boat has other AC electronics that you wish to protect.


Electroprop Waterproof Energy Management System (EMS)

Energy Management prevents battery over charging, under charging and ground faults by monitoring each individual battery and the insulation resistance of the entire system.    The Battery Management System will balance the battery bank by diverting up to 2 amps into any one battery from the other three batteries.

Energy Management increases the life of the battery pack by as much as two or threefold.    Typical battery life for electric boats is 4 years.   Electroprop battery life is often 10 years and our new designs and new batteries may last as much as 15 years before replacement.    Battery Management Pays for itself in as little as 4 years and is a large contributor to our lowest cost of ownership for electric drivelines.

The EMS has 4 voltmeters for each individual battery.   Each Voltmeter has a high voltage and low voltage alarm.    If any one battery exceeds 14.7 volts, the charger is denied as power by the charger relay.    If any one battery has voltage less than 11.5 volts, individual loads can be turned off to protect the battery.

Insulation resistance monitoring insures that the battery remains isolated from the boat.   If at any time a wire was compromised by an errant screw, or chafe or moisture buildup, the Insulation resistance monitor will warn the boat owner.    The boat owner can quickly find the fault by switching off the individual double pole breakers.   This allows the boat owner to quickly diagnose the issue and repair the issue at sea without the need of an electrician.

The EMS balances the battery bank by diverting power from high batteries to low batteries.    This prevents the incremental unbalancing of the battery pack that can happen on every charge and discharge cycle.    The balancer can be shut off when batteries are unattended or not on a charging source.   The balancer is mounted in an aluminum box to provide environmental protection and heat dissipation.

The EMS monitors the remaining capacity of the battery bank by counting amp hours after measuring a set of criteria that determines when the battery is fully charged.

The Energy Management System has a separate DC to DC converter to run the Voltmeters and Alarms.

The Energy Management System is mounted inside a waterproof box.

The Energy Management System disconnects AC power from the charger in the event of a charger internal fault.


Electroprop Waterproof DC Distribution

Electric boats must be able to handle high sustained currents, sometimes as high as 200 amps or more.   This requires components that are rated for the job, and are installation to a higher standard.

Electroprop DC distribution is housed in a waterproof box with waterproof strain reliefs for each cable that enters the box.

All DC breakers are rated for the charging voltages that are being used.   Rating at the charging voltages being used enables AC or DC Hybrid operation.

Main DC breakers are rated at 125 VDC for operation of  up to 96 VDC nominal systems.    Branch Breakers are rated at 80 VDC for 48 volt systems and 125 VDC for 96 volt systems.

Shunt wires are fused with our waterproof, spring loaded, ceramic fuses with water proof boots.    The shunt wires hold full battery potential of up to 150 KW so lets not put that kind of potential on a 14 gage wire!    Its very important that the shunt wire fuses are of high quality for accurate current measurement.

All our breakers are double pole.    Double pole breakers allow for complete isolation of each component, which is essential for trouble shooting at sea.


Victron Solar Charge Controller

Each Electroprop Powertrain comes complete with a Victron Solar Charge Controller.   Up to 35 amps continuous.


Midnite Solar Charge Controller.   

Available as an option for larger solar arrays up to 85 amps


Northstar 210 amp hour Thin Plate, Pure Lead, Deep Cycle,  AGM Batteries with Partial State of Charge Operation.

After selling batteries for over 20 years, and building electric boat drives for 15 years I have come to the conclusion that Northstar builds the finest marine battery in the world.

The Northstar batteries that we use are rated for Partial State of Charge operation, so are a very forgiving battery if left uncharged.   Its still better to charge a battery up after you use it, but in the event that you forget or are on a long trip, your batteries will remain your friend.

While in Partial State of Charge, between 20 and 80%, the Northstar Battery is the most efficient lead acid battery.

The Pure Lead Construction doesn’t short their plates so there is no risk of catastrophic failure that exists with other AGM, GEL and flooded batteries.

The Thin Plate, Pure Lead contruction holds voltage better during discharge allowing for better power and acceleration throughout the charge cycle.

The Size and Shape of the Northstar Batteries allows for alot of energy to be stored in a small footprint.

48 volt systems total 10 KWH’s of energy storage.    Optionally the batteries can be doubled up for 20 KWH’s of storage.     96 volt systems total 20 KWH’s of storage optionally up to 40 KWH’s of storage.

Pure Lead Batteries can be paralleled up permanently at the 12 volt level safely so you can make one double 48 volt battery bank.     Optionally, two banks of 48 can be configured.

Northstar Pure Lead Batteries have the most flexible charging parameters so are best suited for solar and wind power.

The battery pack has large high current wires connected to the DC distribution box, and 5 x 14 gage wires for the Energy Management System.    Each of the 14 gage wires is fused with our very high quality waterproof fuse.    A 3 inch split loom covers all the cables, wires and connectors so no conductive metal surfaces are showing.


House Energy: 

Electroprop Powertrains include a Northstar House Battery and 12 volt charging from the Electroprop Dual Voltage Charger for the house battery.

We can optionally provide a method of charging the house battery from the energy of the propulsion battery, or a DC converter for 12 or 24 volt components.


Electroprop Drive Enclosure Features

Electroprop Propulsion Drives are either open frame, Mariner and Racer,

or in an enclosure,  Sailor, Islander, Seafarer, Cruiser or Voyager.

We prefer and recommend the drives inside enclosures.   Open Frame Drives should only be used where their is a space constraint and require an additional fan(s) to be owner installed,  and in a coaming for high output applications.    Remember:   A motor is only as good as its cooling system.

All Drives have intake ducting to provide relatively cool air from outside the engine room to cool the motor.   This prevents ambient temperature buildup in the engine room.   Ducting enables high power continuous operation of the drive system.

The Electric Motor, Gearbox, Controller, Contactor, Fan Power Supply, Fan and Wiring harness are mounted inside the enclosure.

The enclosures provide protection from the elements.   The wiring harness is waterproof.

The enclosure acts as a Farraday’s Cage which protects all of the electronics mounted inside.     We have moved both the throttle and the Sevcon Clearview Screen inside the enclosure for maximum protection from Lightning.

The enclosure makes the drive quieter as it is essentially a big muffler that everything is mounted within.

The most important feature of the enclosure is forced air cooling.    The Sailor has one electric fan.   The sailor’s electric fan helps to pull air through the motor and around the motor and prevents hot spots from occurring on the motor.    The Islander , Seafarer, Cruiser and Voyager have two fans: one pushes air into the enclosure at the same time as one pulls air out of the enclosure.     The Cruiser and the Voyager are cooled by forced air in conjunction with water cooling through an onboard radiator and machined water jackets in the Controller Mount and Gearbox Mount.    All water cooling is done with the same great metal throughout: aluminum.   Unlike other motors and most diesel motors which have dissimilar metal parts, our all aluminum water cooling system lasts longer through coolant changes and will not corrode due to dissimilar metals immersed in an electrolyte.

The enclosure is equipped with a fully adjustable mounting system for accurate alignment and ease of adjustment.

The Enclosure comes with 2 inch conduit attached to the side of the enclosure for the main power lines which can be on either the port or starboard sides for maximum installation flexibility and maximum insulation of the main DC power cables.


Motenergy Motors for Mariner, Sailor, Islander, Racer, Seafarer and Cruiser

The Motenergy Dual Stator, Permanent Magnet, Brushless, motor has been the workhorse of our systems for years.     Motenergy Motors have low EMI and are ignition proof due to their brushless design.    Motenergy Motors have Sin/Cos Encoders for accurate rotor position sensing.


Perm Motor by Heinzmann for Voyager

The Big 12 inch Perm Motor has Dual Stators, Permanent Magnets, Brushless, and is water cooled for continuous high output up to 21 KW continuous.   This is a strong motor capable of over 200 amps of continuous currents up to 96 VDC.   The Perm Motor has an incredible 94% efficiency making it one of the most efficient motors available today.


Sevcon Controller

Electroprop has enjoyed a 15 year relationship with Sevcon.   Electroprop pioneered the use of Motenergy motors in Sailboats.    Electroprop’s Company boat Kapowai was the original test bed for the Sevcon Controllers running Motenergy Motors.    Over the years the software has been updated many times resulting in higher efficiency and reliability.


Sevcon Clearview Display

The Sevcon Clearview display is now mounted inside the enclosure for maximum protection from Lighting.    The display communicates with the controller over CANBUS.    The display allows adjustment of rpm and acceleration ramps so adjust the personality of the drive to the boat owners liking.    The display has full fault management capabilities to allow for accurate diagnosis of any issue that might arise when the boat is away from the dock.    The display gives readings for Battery Voltage and Current, and Motor Voltage, Current, Temperature, and Controller Temperature.    The display allows for accurate choice of reduction gear or propeller assuring that the motor will always operate at cooler temperatures.    The display was custom programmed by Sevcon for Electroprop.


Browning Helical Gearbox for Mariner, Sailor and Islander

The Browning Gearbox is manufactured in Kentucky to Electroprop Standards which include Corro-Duty Epoxy Primer and Paint for the salt water environment.   A variety of ratios are available from 1.25:1 up to 5:1 to accurately match your choice of fixed or feathering propeller.     The Helical Gearbox is ideal for applications up to 7 KW continuous and in this range provides the highest efficiency of any gear or belt reduction.    It is very easy to change a motor on a helical gearbox.    The Browning Gearbox is lubricated and cooled by Synthetic Oil with first oil change due in 10 years.    The Browning Gearbox is at the center of our no-nonsense approach to low maintenance and long maintenance intervals.     We operate Browning Gearboxes up to 2,100 rpm.     Electroprop drivelines featuring Browning Gearboxes are powered by 48 volt power packs as standard configuration.


Planetary Gears for Racer, Seafarer, Cruiser and Voyager

Planetary Gears are better suited for making power above 7 KW continuous because of their capability of accepting high input rpm from the motor.    Motors make power by torque x rpm, so doubling input rpm will double power.      Planetary Gears through their lubricant by centrifugal force onto the sungear and remain self lubricating up to 6,000 rpm.     Our standard Planetary systems are set up at 4,500 rpm with 96 Volt operation.     Planetary Gears have ratios of 3, 4 or 5:1    Planetary Gears are very quiet and feature very low gear lash for silky smooth operation.


Lightning Protection

A sailboat has the benefit of a mast that provides a cone of protection, typically thought as coming down from the top of the mast on a 45 degree angle.     The stays, shrouds and lifelines further provide an overall Faraday’s Cage effect.   Lightning almost always strikes the top of the mast first.   Protecting a boat from lighting is all about directing and managing the current while protecting components inside the Faraday’s Cage.    What is unique about a sailboat, is that the energy from the lightning strike will go through the middle of the Farraday’s Cage provided by the mast, rigging, lifelines and electrical wires.   For this reason, the energy gets dissipated between all the down conductors – including the main mast down conductor which will take the bulk of the current to ground and shrouds and stays which require side conductors to direct that energy to the waters surface.     Or even better is to use exterior mounted chainplates.

A Faraday’s cage protects component or human beings within a conductive enclosure from the adverse affects of voltage and current.   Essentially all current is conducted around the perimeter of an conductive enclosure and doesn’t get inside the enclosure.    This is what allows line workers to work on high voltage power lines while power is going through them…. the line worker is dressed in a metallic suit which is then connected to the high voltage wire, sometimes as much as a million volts or more.

We recommend enhancing the Faradays Cage of a boat by adding a perimeter cable around the boat at the hull to deck joint, making sure the lifelines are grounded, and adding side electrodes at the waterline to cables attached to each shroud or stay.   One main stem lightning cable stretches along the stem of the boat.    Any larger conductive items mounted outboard (metal tanks, batteries, electrical equipment)should be further protected by a cable passing underneath the component and joining to the stem cable and the perimeter cable.

When a boat gets hit by lightning, it will most likely hit the top of the mast.   The current acts as all current does, taking the path of least resistance to ground.   If the boat is equipped with a down conductor and plate underneath the water, then the bulk, if not all of the current will follow that path.   If the boat does not have an adequate path to ground for the lightning to follow, then the lightning will come down all the stays and shrouds and will drill holes through the hull to get to the ground (water).   In all circumstances, the grounds on the boat, as they conduct current will rise above the potential of the water, and even the water itself will rise above the potential of the surrounding water as the lightning slowly gets absorbed by the earth.    In fresh water, the area of dissipation of lightning is far bigger than in salt water because fresh water is not as conductive.

In a lightning event, all the potentials of the grounding system will rise as the lightning attempts to find ground.    Most boats utilize the diesel engine as the main ground point of a boat.    When the boat gets struck by lightning, the grounds rise in potential and follow the path of the grounds to the diesel engine, through the main drive bearing to the propeller.    The main drive bearing is of high resistance being soaked in oil with a bunch of moving parts.    When the lightning takes this path, it seizes the main drive bearing.     If the ground point is on the side of the engine, the current path could go from the ground point through the block and seize the piston in the block.   That is why it is recommended to run a diesel motor during a lightning storm – to prevent the diesel engine from seizing.

Its a really simple change too…. just keep the motor out of the current path.   Establish ground with a ground plate directly below the mast.    Lag into the lead keel would be a great primary ground.     Do not use the Electroprop as a ground attachment for other electrical systems aboard the boat.   Ground the Electroprop to the grounding system stem cable with a #2 battery cable.     The Stem Cable is a #2 cable layed along the stem from the bow to the stern and is the main ground cable in the lightning grounding system which includes the lifelines, mast, underwater ground plate, and rudder shaft.    You have the choice of whether or not to ground the propeller shaft to the grounding system, which is accomplished by adding a bonding cable across the flexible coupling.

All the electronics are inside the enclosure to protect them by the Faraday’s Cage effect.   We have relocated the motor screen inside the enclosure as well as the throttle so the throttle will be cable actuated.    The arm that attaches to the cable is non conductive high strength plastic to prevent lightning coming to the enclosure through the cable.

The Charger has a surge suppression device that allows the voltage to rise on all AC connections at the same time, preventing lightning from ruining the charger.

We have several other recommendations for lightning proofing your boat, but they all come down to the same basic principle of keeping sensitive electronics out of the current path while providing a good strong current path directed where the lightning will not do any harm.


Flexible Coupling

Each unit is equipped with a flexible coupling by PYI.   The addition of the flexible coupling allows for very accurate alignment down to 4,000 of an inch.   The remaining misalignment is easily absorbed by the flex coupling and prevents binding of the shaft with every revolution which maintains high efficiency.   A large jumper wire is attached to the two sides of the coupling and becomes the only point where the motor enclosure is bonded to ground.



In the old days with diesel engines the rule of thumb when you talked to a propeller man was diameter, diameter, diameter.    Electric motors have changed that to Pitch, Pitch, Pitch!     Pitch is the only way to slow a propeller down, while still maintaining boat speed because it is rpm times pitch that gives maximum boat speed.    Power is then created by overall blade area which is then determined by blade area ratio and diameter.

These “tricks” are really not tricks at all and have been practiced for over a hundred years by older boats and large ships.    The slower a propeller can turn, to make a required thrust, the more efficient it will be.

The electric motor enables the use of larger blade area ratios with larger pitch propellers.    The propeller enables the electric motor to be a fraction of the horsepower of a conventional diesel installation without sacrificing performance.     We have plenty of examples of how our motors get necessary power while being 1/3 of the horsepower of a diesel.    It is this net efficiency that enables electric and hybrid propulsion which gives you far greater enjoyment of your sailing boat.

Other factors do contribute to the vast dissimilarity in horsepower ratings between electric and diesel engines.    A diesel engine with combined reduction gear has very little low end torque so just cant spin a larger propeller like an electric motor can.    The diesel would stall at idle.    To overcome this problem, some diesels are now set to idle at 1,500 rpm so they can take advantage of larger propellers.     It is a fact that diesels a century ago had better efficiency than they do today because the large, older diesels had the required rotational momentum to turn larger propellers, plus the older diesels were getting their horsepower from high torque at low rpms and not from low torque at high rpms, commonplace in today’s small diesel.    The other big factor is many diesels have not been properly optimized and to be sure they are powerful enough, boat builders put in bigger diesels to compensate.    Diesels are matched to propellers at maximum rpm’s, so throughout the rest of the torque curve, the diesel is under utilized.    Electrics, on the other hand, come with a built in dyno.    Current is torque and voltage is rpm.    Each electric motor can be accurately matched to the perfect propeller.    Installing an electric motor is a science, while installing a diesel is still and always will be an art.

There simply is no other upgrade for a boat that provides more enjoyment and works so effortlessly, as upgrading to an electric drive motor.


A Note about Range

In the 15 years that I have been building electric boats I have never had a customer call me up and tell me they lacked sufficient range.     We build systems that are matched to how you use your boat and we can back up any electric motor with a generator for continuous operation.    Hybrids are great because you can choose when to run the diesel motor so as not to back-wind the cockpit or the interior with diesel exhaust- its really simple… just avoid running the diesel when you are going straight downwind.


Use your imagination.

Whatever your needs, we are here to help.    Every boat is different and has different needs.     Weight, Size, and Cost Considerations can be custom made into the Electric drive.    All wire lengths can be customized for your installation or left to trim and fit on the job later.    Some boats may want bigger batteries, smaller batteries, or a feathering prop.     The Electric Propeller Company is a custom motor shop geared to make the highest quality components integrate smoothly together in a synergistic package.

All for you and your boat.    One Electric Powertrain at a time.


The Electroprop Powertrains

Mariner Powertrain



Sailor Powertrain



Islander Powertrain



Racer Powertrain


Seafarer Powertrain


Cruiser Powertrain



Voyager Powertrain