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Plotting Tools

Weems & Plath GPS Plotter

Plot GPS positions and waypoints faster and more easily than ever with the GPS Plotter.  Just read your GPS and place the plotter's alignment holes on your chart's latitude and longitude scales.  Then, open the plotter and mark--your fix is instantly plotted.  It also can be used as a conventional plotter/protractor and parallel rule.


Weems & Plath ParaLock Plotter

Compact and quick position plotter can also be used as a conventional parallel rule, protractor, or ruler.  Particularly useful for smaller or folded charts.  Enables transfer of GPS positions rapidly and easily.


Course Plotter

Weems & Plath Course Plotter

15" plotter features:

  • A semi-circular protractor scaled from 180o to 360o inside
  • Lower edge scaled 1:80,000 and 1:40,000 to accommodate NOAA charts.  
  • Upper edge is scaled 1" = 20 miles to coordinate with VP-OS Universal Plotting Sheets.

Parallel Plotter

Weems Parallel Plotters

Parallel Plotters--simple plotters mounted on a roller that can only move in a parallel direction--are some of the most popular instruments with our customers. They're easy to use for laying out or measuring courses.  Features include:

  • Two sizes
    • Compact--just 8" X 2" for tight work spaces
    • Standard--13" X 3"
  • Distance scales at 1:20,000, 1:40,000, and 1:80,000--ideal for NOAA charts
  • Semi-circular protractor for measuring courses and bearings against a meridian
  • Quarter circle protractor for measuring courses and bearings against a parallel of latitude (standard model only)

Three Arm Protractor

Three Arm Protractor

Three Arm Protractors are favored by many of our commercial customers.  This model features heavy, clear acrylic construction with arms that are rigid enough to trace a bearing line.  

Three Arm Protractors can be used to position and chart from three identifiable shore, landmark, or buoy locations.  Just measure the angles on the protractor's scale to locate your position on the chart.


Portland Course Plotter

Blundel-Harling Portland Course Plotter

Portland Plotters--also known as Breton Plotters-- are the plotters of choice for commercial navigators.  This heavy-duty model features:

  • A moveable compass rose grid.   When aligned on chart parallels it automatically sets the drawing edges on the course bearing required.
  • Variations can be pre-set on the moveable rose for easy compass bearing plots.
  • Edges are graduated in inches and centimeters
  • Large numbers make the plotter easy to read under difficult conditions
Bi-Rola Rolling Plotter Bi-Rola™ Rolling Plotters

Bi-Rola Plotters' patented horizontal and vertical rolling motion simplifies course and plotting calculations with a unique radial arm that allows automatic compass corrections in course plotting.  It's the most completely self-contained plotting device available featuring:

  • Four-way rolling motion
  • Roller body with protractor markings and a nautical mile scale
  • Radial arm with Loran interpolator scales and 200 mm rule
  • Automatic compass corrections
  • Speed-distance-time calculators
  • Two sizes--14" standard and 20" professional models


Weems & Plath Compute-A-Course™

Compute-A-Course is a compact, multi-purpose plotting tool that's ideal for recreational or commercial navigators.  Use it for:

  • Position fixing
  • Course plotting
  • Distance Measurement (scales included)
  • Speed-distance-time calculations

square protractor

Weems & Plath Square Protractor

This plain edge 5" protractor is suitable for plotting courses and bearings.  Your notations can be made directly on the matte plastic surface with a pencil.  Constructed of durable transparent plastic.  Instructions included.


Ordering Information
122016 Weems & Plath GPS Plotter $33.95
132475 Weems & Plath ParaLock Plotter $24.95
121923 Weems & Plath Course Plotter $11.95
122280 Weems & Plath Parallel Plotter--Standard Model $20.95
121914 Weems & Plath Parallel Plotter--Compact Model $19.95
122247 Three-Arm Protractor $29.95
104646 Blundell-Harling Portland Course Plotter $24.95
121844 Bi-Rola Rolling Plotter--Standard Model $89.95
121845 Bi-Rola Rolling Plotter--Professional Model $159.95
121917 Weems & Plath Compute-A-Course $25.95
122217 Weems & Plath Square Protractor $8.95

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(800) 584-4114 - (510) 769-1547