How to Measure Sailboat Turnbuckle Swage Studs | Expert Advice

Threaded turnbuckle swage stud

We are going to show you how to measure imperial (non-metric) turnbuckle swage stud sizes for standing rigging (shrouds, forestays, backstays…) and life line terminations.  The following will be measured and used to specify replacement studs or turnbuckles:

  • Stud diameter
  • Wire diameter
  • Thread Length
  • Thread Count
  • Right or Left hand threads



The only tool you will need is a set of calipers.  Using a ruler to measure is not accurate enough if you want to be 100% sure.


Turnbuckle threaded stud diameter

  1. Diameter is measured with your calipers running across the rows of threads.Turnbuckle threaded stud thread length
  2. Thread count is the number of threads over a one inch range and will be 20, 24, 28, 32…
    Turnbuckle threaded stud thread hand
  3. Hand is the slant of the threads either to the left or the right when looking at the stud side on.  Right-Hand (RH) studs tighten clockwise, and Left-Hand (LH) studs tighten counter-clockwise.turnbuckle stud thread length
  4. Thread length is the length of the stud that is threaded.  Generally you will find that life line studs are considerably shorter than standing rigging turnbuckle to measure 1/19 wire with calipers
  5. Wire size is the diameter of the wire and is measured with your calipers.  Be sure to measure the wire at its largest diameter (correct orientation to the surface of the calipers).  See illustrations above.  Wire sizes are generally 3/32”, 1/8”, 5/32”, 3/16”, 1/4”, 9/32”. 5/16”, 3/8”…


Now string all of your measurements into a specification using the following example:

Diameter: ½”
Threads: 20
Hand: Right Hand
Thread Length: 3-1/2”
Wire Size: 5/16”

The stud size in this example is expressed as: ½-20 R.H. x  3-1/2” for 5/16” wire

Note: Be sure when ordering replacement threaded studs or turnbuckles that you do not choose life line fittings for standing rigging.  Life line studs and fittings are not appropriate for standing rigging (mast) loads.

FYI: Most U.S. turnbuckles use swage studs that are left handed.  This way the threads are opposite the lay/twist of the wire.

See our full offering of studs and turnbuckles:

Standing rigging turnbuckles
Standing rigging studs
Life line turnbuckles
Life line studs

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