Hey everyone, welcome to r/SolarSailors!

I started this community because I’ve been researching electric sailboat conversions and realized how scattered all the useful information is. There are great videos, forum posts, products, and individual builds out there, but I wanted one place where we could compare real systems, share mistakes, and help each other build better solar-electric sailboats.

I’ll start by introducing my own project.

I live aboard a 1977 Ericson 35-2 in Marina del Rey, California. She currently has an old Universal Atomic 4 gasoline engine. It has served these boats well for decades, but mine is getting tired, and I’d rather put my time and money into converting the boat to electric than rebuilding the gasoline system.

My near-term cruising goals are Catalina and the Channel Islands. Eventually, I want the boat capable of serious offshore cruising and possibly a circumnavigation.

I know solar panels aren’t going to turn a 35-foot sailboat into an unlimited-range powerboat. My goal is much more realistic: quiet and dependable auxiliary propulsion for getting in and out of harbors, dealing with calms, and handling emergencies—with enough solar generation to slowly recover that energy while sailing or anchored.

Right now, I’m leaning toward a ThunderStruck 24 kW liquid-cooled motor running at 96 volts.

The rough plan includes:

A 96V LiFePO₄ propulsion bank
A reduction drive connected to the existing propeller shaft
Around 800–1,000 watts of solar
Shore-power charging
A DC-to-DC converter for the boat’s 12V systems
Proper marine-grade fuses, contactors, disconnects, pre-charge protection, monitoring, and emergency shutdowns
Regeneration under sail, if it produces enough power to be worthwhile
A future smart control and monitoring station for the entire boat

This is still very much in the research phase. Nothing has been ordered, and I’m completely open to having my assumptions challenged.

The biggest question is whether 24 kW is reasonable or simply more motor than this boat needs. A 10–15 kW system would cost less and might be a better match, but having extra power available while entering a harbor against wind or current is attractive.

Of course, a bigger motor doesn’t magically give me a bigger battery.

Once the system is properly designed, I would remove and hopefully sell the Atomic 4, fuel tank, exhaust, and other gasoline equipment(so if anybody is looking for an original motor let me know). I’d then install the batteries, charging equipment, cooling loop, wiring, safety equipment, and controls before mounting the motor and reduction drive.

I’m hoping to reuse the existing engine bed mounting points with a universal motor mount.

Where I need your help!

I’d really like to hear from people who have actually built, operated, repaired, or lived with these systems.

A few of my biggest questions:

How much continuous power does a 35-foot displacement sailboat actually need to cruise at 3, 4, and 5 knots?
Is 24 kW useful reserve power, or would a 10–15 kW motor be a smarter choice?
What size battery bank gives a practical balance of range, weight, and cost?
What real-world range are you getting, and at what speed?
How did you mount and align your motor, reduction drive, coupling, and shaft?
Did you keep the original propeller or change its diameter, pitch, or blade count?
Does the system need a dedicated thrust bearing?
How much energy are you actually getting from your solar array each day?
Is 800–1,000 watts enough to meaningfully restore propulsion energy?
Has regeneration been worthwhile, or is it more trouble than it’s worth?
How much speed do you lose while regenerating?
What has failed, corroded, overheated, or behaved differently than expected?
What would you absolutely do differently if you built your system again?
Were there any insurance, inspection, or survey problems after converting?
Do you carry a generator or another emergency charging option?

If you already have an electric sailboat, please share whatever numbers you’re comfortable sharing:

Boat and displacement
Motor and controller
Battery voltage and usable capacity
Propeller and reduction ratio
Solar wattage
Cruising speed and power consumption
Realistic range
Approximate total cost

I’m not here to pretend I already have everything figured out. I’m here because I don’t and because I think pooling our experience can help all of us avoid expensive mistakes.

I’ll share my measurements, diagrams, budget, installation progress, mistakes, and eventual sea-trial results as the project moves forward.

Whether you’re already cruising under electric power, halfway through a DIY conversion, or just fascinated by the idea, I’m glad you’re here.

Welcome aboard!

Hey everyone! I'm u/Kushmandan, a founding moderator of r/solarsailors.

This is home for all things related to solar sailboats.

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Sailboat Specific People

Hey everyone,

New solar sailboat community if anyone here is in here is interested

I'm Starting My solar Electric Sailboat Project

Where I need your help!

👋 Welcome to r/solarsailors - Introduce Yourself and Read First!