A sailboat gooseneck is a heavy-duty, usually stainless steel or aluminum swivel connection that attaches the boom to the mast, allowing the boom to pivot vertically and rotate horizontally. It often includes attachment points for the main sail tack, boom vang, and topping lift, and may slide on a mast track for height adjustment.

Key components and characteristics of a gooseneck include:
Swivel/Toggle Mechanism: Enables the boom to move up/down and side-to-side.

Mast Attachment: Can be a fixed bracket or a slide that moves up and down a track on the mast for luff tension adjustment.

Boom Attachment: A U-shaped part or casting that fits over the end of the boom.

Fasteners & Pins: Locking pins and bolts that secure the assembly, often requiring regular inspection for corrosion due to high stress.

Attachments: Built-in hooks or lugs for attaching the boom vang, reefing lines, and sail tack.

Proper maintenance includes regular lubrication and checking for cracks, as it is a high-stress area.