The orders of magnitude don't look so bad. Some quick Googling puts the weight of three masted schooners at 300-400 tons; a cord of firewood weighs 2 tons, so

The orders of magnitude don't look so bad. Some quick Googling puts the weight of three masted schooners at 300-400 tons; a cord of firewood weighs 2 tons, so that's between 150 and 200 cords of firewood. Some of that was reused in the escape-raft and some of it was presumably unrecoverable, but if they were able to recover 25% of it, that's somewhere in the neighborhood of 50 cords of firewood, or around 3 cords per year of the 15 years. 3 cords is a reasonable amount for a house to use for heating in a heating season in the US. That's less than a year, but you're probably burning it faster than you would if you were carefully husbanding a fire and occasionally using it for cooking or warmth or light. So it's totally plausible (which is good, considering it happened), but the numbers are close enough that I couldn't guess whether you'd expect the average shipwreck in similar circumstances to run out of wood after ten years or have enough for a hundred, without having more information about the burn rate in this particular situation or how much wood they actually were able to recover.