Lubber Line

The fixed reference mark on a compass that represents the vessel’s fore-and-aft heading line.

The heading is read where the lubber line intersects the graduations on the compass card. The line and compass must be installed in known alignment with the vessel’s heading reference; an installation error becomes part of the compass error.

Some compasses have additional marks for viewing from another steering position or for relative bearings. These should not be confused with the primary lubber line used for the vessel’s heading.