The Marlinspike or Marlin Spike is a tool designed for use in the marine and sailing industry. The tool is useful for untying knots and splicing rope. This tool is made of stainless steel with a smooth tapered shaft and an Eye near the tip to aid in sewing.
When rope knots become tight due to tension and possibly wet this tool can be used by inserting it into the knot and prying it loose until it can be untied. Since the shaft of the tool is smooth it will not cut or damage the rope.
You can also use it to add a smaller rope to an already existing knot by splicing it into the knot using the eye of the tool. Simple sewing jobs on a sail can be accomplished using the eye as well.
This tool is a descendant of the similar Victorinox tool, the Sacking Needle found on much earlier models.
The 93mm Marlinspike appears a little more robust that the large sacking needle, and has very smooth curvature.
The point of the Sacking-Needle is noticeably sharper (needle-sharp), than the rounded point of the Marlinspike.
See: Shackle Opener