Diagnosis & Decision 11 min read

Nomad autonomy score: how to assess a van or sailboat before you buy

By Azimut AI · May 30, 2026 · Updated October 7, 2026 · Our editorial policy

A converted van or a sailboat is a major purchase, and a viewing mostly covers what you can see: bodywork, hull, interior. Autonomy comes down to figures — battery Wh, solar W, tank litres — set against the intended use: where, when, how many on board. Here is what the Nomad score measures, and how to use it before you buy.

pillars: energy, water, food, safety

30%

the weight of water, the heaviest pillar

5–95

the scale of each pillar and of the score

1,500 Wh

a van's daily reference need (sailboat: 2,000)

The Nomad score: 4 pillars, not 1

• Energy (25%) — what a reference 100 W portable panel produces at the destination — peak sun hours by latitude, adjusted for the season — against the activity's daily need: 1,500 Wh for a van, 2,000 Wh for a sailboat. With that single panel, the pillar stays below 50 for a van and below 40 for a sailboat wherever you go: it measures the place's sun, not the vehicle's installation.
• Water (30%) — the natural water available, estimated from the place's annual rainfall, against the season's need: summer calls for more water, so the same resource covers less.
• Food (25%) — how well the activity carries food — a van has its fridge, a sailboat its galley stores — a little better where resupply is easy. Trip length only weighs on hiking and cycling, where everything is carried.
• Safety (20%) — how harsh the climate is (high latitudes, tropics, winter) and the activity's own risk, higher at sea than in a van.

The weights are the same for every activity; what changes from a van to a sailboat are the daily needs, the way food is carried and the risk. Each pillar, like the overall score, is bounded from 5 to 95. This score measures the potential of the place and season; the vehicle's own equipment is scored in the 3D twin and the saved kit, on the same weights. See also the Home counterpart of the score (in French): four pillars for a house too — energy, water, food, heating — with its own weighting.

5 questions to ask the seller first

1. What is the batteries' real usable capacity (Ah × depth of discharge)?

A 200 Ah lead-acid battery at 50% discharge = 100 Ah usable; a 200 Ah LiFePO4 at 90% = 180 Ah usable, a little over 2 kWh at 12 V. Compare that with the score's reference need: 1,500 Wh a day in a van, 2,000 Wh on a sailboat.

2. How much solar is installed, and what has the charge controller logged?

In the score's model, a 100 W panel gives about 150 Wh a day in December in Lille and about 500 Wh in June in Marseille: more than three times as much. If the MPPT controller keeps a history, ask for it, winter and summer.

3. How much drinking water is carried, and with what filtration?

Compare the tank with the reference need: 4 L per person per day in a van, 3 L on a sailboat. For two in a van, 100 L last about 12 days. Beyond 100 L, also check where the tank sits (weight, frost protection).

4. Does the heating suit the intended season?

Neither the score nor the twin models heating: this is a check to make yourself. Ask for the power, the unit's age and whether it has run in the temperatures you expect; insulation matters as much as power.

5. What emergency communication works off-grid?

A phone alone is not enough out of coverage. A satellite communicator (inReach, Zoleo…) or, on a sailboat, a VHF radio: that is what raises the safety pillar in the twin.

Reading the score before you buy: 3 bands

The app colours each pillar, like the overall score, with two thresholds: 70 and 40. Here is how to read them before a purchase.

Below 40 — “Needs work”

For the intended place and season, at least one pillar is weak: the site covers that need poorly, and everything will rest on the vehicle's equipment. Before buying, check that its battery, panels or tank close the gap — or change the season or destination.

40 to 69 — “Partly covered”

The site covers part of the needs. Compare the vehicle's real equipment — battery Wh, solar W, tank litres, fridge — with the activity's daily needs, then enter it in the 3D twin: it scores your own gear on the same weights and shows how many days of autonomy it gives.

70 and above — “Well prepared”

The place and season suit the activity. That says nothing about the vehicle's condition: still ask the five questions above, and redo the score if the destination or season changes.

À retenir

The Nomad score rests on 4 pillars — energy, water, food, safety — weighted 25 / 30 / 25 / 20 and bounded from 5 to 95; the weights are the same for every activity.
A van and a sailboat differ in their reference needs: 1,500 Wh a day and 4 L of water per person for a van, 2,000 Wh and 3 L for a sailboat, with a higher activity risk at sea.
The score measures the potential of the place and season; the vehicle's equipment is scored in the 3D twin and the saved kit, on the same weights.
Real usable capacity: a 200 Ah lead-acid battery at 50% discharge yields only 100 Ah usable, versus 180 Ah for a 200 Ah LiFePO4 at 90%.
The app's thresholds: 70 and above “Well prepared”, 40 to 69 “Partly covered”, below 40 “Needs work” — before buying, compare battery, panels, tank and fridge with the activity's daily needs.

FAQ

Why assess a van's autonomy BEFORE buying?

Because what makes autonomy — battery, panels, tank, fridge — is hard to judge on a viewing and rarely replaced for free. The Nomad score tells you what the intended place and season offer the activity; the vehicle's equipment has to cover the rest. Entering it in the 3D twin shows, pillar by pillar, what is missing.

What are the key indicators to check?

The ones the 3D twin takes into account: battery capacity (Wh), installed solar power (W), water carried (L) and its filtration — a watermaker on a sailboat — the fridge, which adds about 250 Wh a day to consumption, and an off-grid way to call for help. Heating is not modelled: check it separately for the intended season.

Is the score valid for a sailboat too?

Yes, with the same weights: water 30%, energy 25%, food 25%, safety 20%. What changes are the reference needs — 2,000 Wh a day instead of 1,500 for a van, 3 L of water per person per day — and a higher activity risk in the safety pillar. The 3D twin models what is specific on board: panels on the stern arch, a watermaker (about 25 L a day at anchor), a VHF radio.