Spreaders are horizontal or angled struts (spars) attached to a sailboat's mast that hold the standing rigging (shrouds) away from the mast. They increase the angle of the shrouds, improving lateral stability, strengthening the mast, and reducing compressive loads, allowing for a lighter, thinner mast.

Key Functions and Details
Support & Stability: By pushing shrouds out, spreaders ensure the mast stays straight and secure under sail pressure.

Mast Bend and Tuning: Angled or "swept-back" spreaders are used to control the curve (pre-bend) of the mast to adjust sail shape for different wind conditions.

Types: Spreaders can be fixed (most cruisers) or swinging (common on racers). Boats may have multiple sets (e.g., double, triple) for increased support on tall masts.

Construction: They are typically made of aluminum, stainless steel, or carbon fiber.

Location: The topmost spreader is also a common place to fly courtesy or club flags.

Spreader Anatomy
Spreader Base: Attached to the mast, sometimes on adjustable brackets.

Spreader Tip: The outboard end where the shroud is secured.

Spreader Angle: Can be perpendicular to the mast or swept backward to control mast bend.