Which stay extending from the mast to the transom influences the shape of both the mainsail and the jib?

• A. Forestay
• B. Backstay
• C. Shroud
• D. Vang

Answer: (B)

Tension on the backstay changes how the mast bends toward the stern, and that bend alters the shape of both sails. When you tighten the backstay, the mast bows backward, flattening the mainsail’s upper portion and reducing draft, which depowers the sail. That same mast bend increases the forestay tension, pulling the jib’s luff taut and flattening the jib as well. Loosening the backstay lets the mast straighten more, increasing draft and power in both sails. The forestay, shrouds, and vang all influence sail shape in their own ways, but the stay from the mast to the transom is the one that directly affects both the mainsail and the jib, making it the correct choice.