Presenting Arpeggio.one
Why did I build this?
It started during the pandemic. I bought a vessel — rundown, leaking like a sieve — and fixed her up. Felicitas was her name. I wanted electric propulsion. Not because I’m anti-diesel — I kept the engine because sometimes you just need guaranteed thrust in an emergency: bad weather, injury onboard, or system failure. Electric is elegant, but diesel is decisive. I believe electric is part of the future — but redundancy is timeless.
I’m a software engineer, but I grew up with soldering irons and floppy drives. My first hack was bypassing the key-lock switch on a 286 PC when I was five. My parents thought computers were a distraction. I thought they were a doorway.
You can try the tool at https://arpeggio.one.
Felicitas is a 28-foot lwl (32' LOA), 11.6’ beam boat with a draft of ~2 feet. Fully loaded with four people and water tanks (~15,000 lbs), she reached 2.7 knots on just 1 kW. Here’s a demo.
Most calculators assume planing hulls or bake in extra buffer to sell outboards. Arpeggio asks: what’s the minimum to move? No wind, dead calm water, just physics. You decide the reserve.
It’s not about “more is better.” It’s about precision, optionality, and sustainability.
I’m now building Moonshot. She’ll be longer, stronger, better laid out. But before anything’s installed, it gets modeled.
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Arpeggio helps you:
- Model hull resistance (wave-making, skin, and prop drag)
- Compare inboard/outboard, series/parallel hybrid options
- Explore tradeoffs in speed, weight, and range
- Estimate solar ROI with degradation factored in
Other calculators said I wouldn’t move. This one nearly convinced me I needed 3x the power. Turns out, you can’t always trust off-the-shelf assumptions.
I cross-referenced builds like Sailing UMA (sailinguma.com), the Lorna Jane project (itllneverwork.boats), the UK shrimp trawler retrofit (YouTube), and the Indigo Lady Voyage 440 catamaran conversion (YouTube) — all real-world projects that helped ensure Arpeggio’s math matched reality.
I even matched Arpeggio’s performance projections against the published specs of the Silent Yacht 55 — and ended up within ±0.5 knots.
Arpeggio uses a fast numeric solver to iterate hull speed under realistic loads. Binary search gave better convergence than Newton’s method. And yes, it’s open to feedback.
Why build instead of buy? Because sometimes, to do it right, you have to DIY. Just ask the couple who bought a $2M HH44 — beautiful, but a nightmare to maintain. Lady K Sailing explains it here.
Build because it gives you agency. Because modularity and repairability are more valuable than convenience and aesthetics. And practically speaking, refitting also saves old boats from landfills — extending their life and giving them a new mission.
Arpeggio isn’t just a tool. It’s also a philosophy:
- Take only what you need.
- Keep your options open.
- When in doubt, run the numbers.
More to come. Moonshot deserves its own story.
Dead wind, calm seas, and warm days.
