Every customer asks the same question. What will this boat cost me over its life, compared with diesel?
For years we answered it inside Navalt, first with spreadsheets and later with an internal calculator. It carried our vessel library, speed-power curves, duty cycles, battery packs and our full price book. It gave the right answer. But it gave it only to us.
The answer does not travel. Diesel price, electricity tariff, cost of capital and operating hours change the result by an order of magnitude between India, Israel and Canada. A payback figure from Vaikom means nothing to an operator in the Seychelles. So I decided not to publish an answer. I would publish the method, and let every operator put in their own numbers.
It is the same reason I wrote Solar-Electric Boats: Plan, Build and Benefit four years ago: to help decision makers make the switch to solar-electric. The book showed them how to plan and build one. The app shows them whether it pays, on their own numbers.
The first decision was to use the same engine we use internally. If the public tool and our internal model ran on different math, they would drift apart, and one day someone would find the gap. So the calculation engine stays as it is. Only the inputs changed.
Our price book came out. Vessel costs, propulsion prices, battery cost by chemistry. None of that belongs in public. In its place, the user names a project, enters the powertrain and battery directly, and fills in their own commercial and operating numbers. Physics, efficiencies, finance and emissions keep sensible defaults, because most operators will not know their transfer efficiency and should not have to.
The app has four modules: Hull, Hydrostatics and Stability; Seakeeping; Resistance, Propeller and Propulsion; and Economics. The idea is to start from the hull form and carry the design through every step to the final number. The first three are still in development, but you can already check them out.
The Economics module is nearly done and ready to test. You describe the boat and how it runs: speed, route, hours, the segments of its duty cycle. It works out power, energy, solar contribution and battery size. Then it gives capital cost, operating cost, battery replacement, net present value, breakeven, and CO2 against a fossil fuel boat doing the same work. Do check it out and give feedback.
Try it here: https://solarboats.build/
If you find something missing, or a feature that would help your decision, tell me. We will be happy to add it.
Shipyards and design houses are welcome too. If you are looking to electrify your boats, enter your vessel directly, or share its speed-power curves and we will add it to the default vessel list. You can electrify it with Greenship systems or any alternative system.
