The honest answer starts with what we haven’t done. Our proof — a thousand nautical miles, unsupported — was sailed in the summer and fall of 2024. We have not yet run a full Pacific-Northwest winter passage, so we are not going to hand you a July graph and call it February. When the winter data exists, it goes straight into the log, numbers and all.
What we can tell you is how the boat is built to behave when the sun is thin — because that was a design assumption, not an afterthought. SV Endurance carries a 1 kW array on a high-voltage 100 VDC bus feeding a 24.48 kWh propulsion bank at 48 volts. On a bright day the panels do the work. On a dark one, the bank is a reservoir you draw down slowly. The system was never sized for “the sun always shines” — it was sized so a run of grey days doesn’t strand you.
The discipline that makes winter workable is a floor, not a full tank. Over the 1,000 NM trial the array harvested more energy than the motor consumed — the 48 V bank never fell below 50%. Half the bank is a reserve we hold to, not a number we chase to zero. Shorten the days and that floor matters more, not less: you plan the run against the charge you actually have, and you keep the reserve deep.
There is also a lever winter hands you that a diesel never did: speed. At 2.5–3.5 knots the boat draws somewhere between 200 W and 1 kW — against roughly 3 kW to push the same hull to a diesel-style 4.2 knots. On a short winter day, easing off half a knot can be the difference between arriving with the bank up and arriving with it down. The trade is real and it is yours to make.
So: no winter slogan, and no fabricated winter curve. What we can do is show you the envelope for your boat, on your cruising ground, across the seasons — which is exactly what the configurator is for. Run it, watch the daylight budget shrink through the year, and decide with the numbers in front of you.