What is that do-dad? (The Rigger’s Gauge)

My Rigger's Gauge  the front side is SAE the backside is metric

My Rigger’s Gauge
the front side is SAE the backside is metric

Some of you may be asking “What is a rigger’s gauge?” and “Why do I need one?” A rigger’s gauge is a simple graduated metal or plastic plate used to size different round stock on your boat: bolts, wire, standing rigging, stanchions, rope, cordage, lines, etc. As you can see from the picture: it’s a silly simple tool, doesn’t cost much, and takes up very little space. I store mine neatly inside the cover of my Chapman’s Piloting and Seamanship book for safe keeping.

The reason I always keep one my boat is to save me my precious money, time, and sanity (three things I’m usually low on). Having the ‘exact’ size of a line, wire or stanchion increases your success of getting the correct part the first time.

You may think oh I’ll just size it with a tape measure and run down to the local marine supply store and pick one up. Only to get there and find said widget comes in 1/2 inch and 7/16 inch sizes. You thought you had a 1/2 inch but now you are not so sure.

You now have 3 options:


  • Go back to your boat and get a more accurate measurement, if you can. Once again this creates a second trip to the store.
  • Buy both and return the wrong size. Now you have either a second trip or you’ll forget and waste money on something of no use.
  • Take a guess and buy one size. Why not you probably have a 50/50 chance, right? Maybe, till you factor in Dr. Murphy and his annoying law. (I also have a hypothesis that marine supply stores are like casinos and the grind 1 favors the house.) The odds are not on our side and it’s probably a second trip to the store.

This problem statement only worsens when ordering something on-line or from the marine supply store’s warehouse. You get double wammied with longer turn around times and possible restocking fees.

 3/16 inch parachute cord being measured. (3/16 para-cord is what I use to tidy up the sail locker)

3/16 inch parachute cord being measured.
(3/16 para-cord is what I use to tidy up the sail locker)

There’s a quote from Wyatt Earp “Fast is fine but accuracy is final…” that sums up the usefulness of this tool. Pulleys and clutches are designed to operate optimally with specific sized lines. Likewise electrical wires are designed to handle specific loads over determined lengths. You need to match your rigging properly to keep your boat safe and reliable. Guessing and measuring round stock with inappropriate tools may work at Home Depot, but on a complex system like a boat where everything is engineered to handle a pantheon of forces you need to be accurate.

When I went to replace my trusty old gauge(it was almost 15 years old), I figured they would be as plentiful as potato chips and every store with the word ‘marine’ in it would have a pallet of them. Unfortunately finding one was a little trickier than I originally envisioned. Thank God for the internet, I was able to find them online at hamiltonmarine.com for a very reasonable price. So reasonable in fact, I bought 4 of them: 2 for myself and a couple for a few buddies.

Hopefully by shining some light on this often over looked tool I can save my sailing brothers and sisters out there some time, money, and frustration. I’m always on the lookout for time saving tools and tips. Do you have a time saving widget in your tool box? Drop me a line, I’d love to hear about it!!


  1. ‘The Grind‘ is a casino term for how the house grinds away at your money
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  1. Jessica Cole on October 25, 2014

    This is very cool and reminds me that I should alsYs carry a tape meSure

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