Diagnostic & Decision 10 min read August 4, 2026

Sailboat autonomy score: assess your boat before extended cruising

A sailboat that performs well on summer coastal hops is not, by that fact alone, ready for extended cruising. Abandoned voyages rarely come down to the hull: they come down to unquantified margins — a battery bank that can't last the night under autopilot, water counted too tight, a liferaft never serviced. A 4-axis diagnostic framework before casting off.

Nomad score axes

24/7

the autopilot steers — the most underestimated load

0–100

score scale

3 wks

minimum margin between diagnostic and departure

Purchase score and departure score: two different diagnostics

The pre-purchase score assesses a potential: what the boat could reach after a refit. The pre-departure score assesses a state: what is actually on board, serviced and tested, for the precise route of the coming months.

An 82/100 at purchase coexists without contradiction with a 45/100 at departure: the original bank has aged, the watermaker hasn't run since winter storage, the liferaft is out of its service window. That is exactly what the second diagnostic goes looking for.

The 4 axes of the Nomad sailboat score

• Onboard energy — Ah/day balance underway (autopilot, fridge, AIS watch, nav lights) vs usable bank and charging mix (solar, hydrogenerator, alternator). The most underestimated load: the autopilot, steering 24/7.
• Fresh water — tanks + emergency jerrycans vs days at sea between stops; watermaker tested before departure, consumables on board.
• Safety & communication — liferaft within its service period, registered EPIRB/PLB, DSC VHF wired to GPS, AIS transceiver, complete grab bag, satellite communicator.
• Boat-crew-route fit — standing rigging inspected, seasonal weather window respected, crew experience with night sailing, bail-out ports along the route.

Reading the score: 3 decision bands

0–40 — Postpone departure

Too wide a gap between the intended route and the boat's actual state. Scale back the ambition (coastal) or push back a season.

40–70 — Targeted refit before casting off

Departure feasible after a quantified action list: renew the bank, service the raft, test the watermaker, complete the grab bag.

70–95 — Ready to sail

Autonomy validated for the planned route. Re-score if the season slips or the route stretches.

Key takeaways

The departure score assesses the boat's actual state for a dated route — not its potential, as the purchase score does.
Four axes: onboard energy, fresh water, safety & communication, boat-crew-route fit.
The autopilot is the most underestimated consumer: it steers 24/7 on extended cruises.
Three decision bands: 0–40 postpone, 40–70 targeted refit, 70–95 ready to sail.
Score at least three weeks before departure: the minimum margin to correct without emergency surcharges.

FAQ

How does this differ from the pre-purchase score?

The purchase score assesses refit potential on a boat you don't own yet; the departure score assesses the actual state of the boat — equipment serviced, tested, consumables aboard — for a dated route. They complement each other at different moments of the project.

How long before departure should you score?

At least three weeks: the realistic lead time for a liferaft service, a battery order or rigging work without emergency surcharges. Scoring the day before departure leaves no room to correct anything.

Does the score replace a marine survey?

No. It formalises autonomy preparation (energy, water, safety, route). The structural condition of hull, keel and rigging belongs to a marine surveyor or rigger — the score assumes that baseline is sound.