Why long merchant voyages did not always mean scurvy

When was scurvy brought under control on long voyages?

No date is established in this answer. Merchant crews could replenish fresh food at intermediate ports and carry more provisions per person; naval ships kept on station for months faced a harder supply problem.

The comparison shows why voyage length alone is a poor measure of nutritional risk. East Indiamen had smaller crews, more storage per sailor, and planned calls where vegetables and other fresh supplies could be acquired. A warship held off an enemy coast could be denied those replenishment opportunities for months even if its total route was shorter. The key variable was access to fresh food through a logistics network, not simply the distance printed on a chart.