Parallel Rule — Captain Fields 500 mm

📐 Precision Navigation • Professional-Grade • Built for Chart Work

The Captain Fields 500 mm Parallel Rule is a serious navigation instrument, designed for accurate, repeatable course plotting on paper charts. Trusted by skippers, navigators, and maritime students, this full-length parallel rule delivers the precision and stability required for traditional chart work—whether at sea, in the classroom, or at the chart table ashore.

Made to professional standards by Captain Fields, it reflects the enduring value of manual navigation skills in an increasingly digital world.

🧭 Why the Captain Fields Parallel Rule Is a Navigation Essential

📏 Full 500 mm Length — Built for Real Charts

• 500 mm working length is ideal for standard and large-format nautical charts

• Allows long, accurate transfers of bearings and courses without repositioning

• Perfect for coastal, offshore, and passage-planning charts

This length strikes the sweet spot between control and coverage.

🔁 Accurate Parallel Motion

• Twin-arm parallel linkage keeps edges perfectly parallel during movement

• Enables precise transfer of bearings from compass rose to course line

• Maintains alignment across multiple moves—critical for safe navigation

This is the core advantage of a well-made parallel rule: confidence in every line you draw.

📐 Clear Graduations & High Visibility

• Bold, easy-to-read markings assist with course drawing and measurement

• Transparent construction allows full visibility of chart detail underneath

• Reduces parallax error and improves accuracy

Every design choice supports clarity and precision.

🛠️ Durable, Professional Construction

• Manufactured from high-quality, clear acrylic for strength and longevity

• Rigid enough to resist flexing during use

• Smooth edges glide cleanly over charts without snagging

Designed for repeated daily use in marine and training environments.

⚓ Designed for Traditional Chart Navigation

While electronics dominate modern navigation, parallel rules remain fundamental for:

• Teaching navigation principles

• Cross-checking electronic courses

• Passage planning and logbook work

• Maintaining core seamanship skills

This tool keeps those skills sharp.

📐 Specifications

• 📏 Length: 500 mm

• 📐 Type: Twin-arm parallel rule

• 🧭 Use: Course plotting, bearing transfer, chart navigation

• 🛠️ Material: Clear acrylic

• ⚓ Application: Nautical charts, training, professional use

🎯 Who This Is For

• ⚓ Skippers & sailors — accurate manual plotting and backup navigation

• 🧭 Navigation students & instructors — essential classroom equipment

• 🚢 Commercial & professional mariners — chart table reliability

• 🗺️ Traditional navigators — those who value precision and discipline

• 🎁 Maritime gift buyers — a practical, meaningful navigation tool

⭐ Why Choose Captain Fields?

Captain Fields instruments are known for practical design, accuracy, and durability. Their tools are made to be used—not displayed—and have earned a reputation for reliability in both training and real-world navigation.

The 500 mm Parallel Rule is no exception: simple, precise, and dependable.

Plot with confidence—every time

Add the Captain Fields 500 mm Parallel Rule to your chart kit and enjoy the assurance that comes with precise, traditional navigation.
Add to cart and keep your chart work accurate and disciplined.