Weems Navigation Protractor


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  • Updated version of Breton & Portland Plotters
  • Movable compass rose grid
  • Edges graduated in inches & centimeters
  • Pencil & sharpener included
  • Lifetime warranty



Product Code:



In Stock

This navigation tool is versatile and can be used to lay off a course or a bearing, measure distance between any two points, plot a position on a chart from a given set of coordinates, or determine the coordinates of a position on a chart. It is an update

Product details
  • Product Dimensions: 15.2 x 5.2 x 0.5 inches
  • Shipping Weight: 5.6 ounces (View shipping rates and policies)
  • Domestic Shipping: Item can be shipped within U.S.
  • International Shipping: This item can be shipped to select countries outside of the U.S. Learn More
  • ASIN: B000IMT1WI
  • Item model number: 255

I ordered five of these plotters for a navigation class I teach because I have owned for 13 years, and still own, an earlier model, still labeled "255" but without the black knob. My plotter has withstood travel in an overfilled backpack, it has been squeezed and twisted, and is still functional as if it were new. Two out of the five plotters I ordered arrived cracked and had to be returned. For a third, which I am about to return, the protractor plus knob detached from the larger, rectangular ruler since the cheap brass rivet holding it fell off.

Close comparison between my old plotter and one of the five I recently bought shows the following differences: 1) the black knob model is made of clearer, more transparent plastic than the older model, however the latter works just fine as far as lining up to meridians and parallels; 2) the plastic of the black knob model is about 2/3-3/4 as thick as the old one; 3) the plastic of the black knob model is brittle compared to the old model; 4) the black knob model plastic warps due to temperature changes; 5) the rotation of the protractor on the black knob model is not as smooth as the rotation on the older model; 6) the black knob creates a focus point on the ruler which can crack if pressure is inadvertently applied to the knob; 7) the black knob model has a brass rivet holding the knob to the ruler, whereas the older model has a stainless steel rivet.

My guess is that Weems&Plath entrusted the design and production of the plotter to some new manager who decided that transparency of the plastic and saving a few cents on plastic thickness and other materials were the overriding goals. In the process, W&P sacrificed plastic qualities like robustness, resistance to bending and twisting, resistance to cracking, resistance to temperature variations and, for good measure, added a useless knob. W&P ended up with a product which does not even survive a few minutes of plotting in a classroom setting, and which would be absolutely unreliable in a marine environment.

Don't buy it!

First let me say that I'm a fan of Weems & Plath products...however, this one falls short of expectations. Very flimsy and don't expect it will hold up for long. Ended up having to return it because it had cracked by the time I received it. I don't blame the seller but rather the material that they used to make it. I used other ones that where much more sturdy.

Bought this and several other navigation tools for the ASA 105 class, this was by far the best/easiest to use and most accurate of them all. No moving it across the chart hoping it's still parallel to the bearing taken from the rose. You don't use the rose at all except to read variance; you line up the grid lines in the protractor wheel with either a latitude or longitude line then set for the desired course, including adjustment for variance, or measure a bearing working in the reverse of that process.

Unlike other reviewer's comments I found this well constructed and useful. Out of all the navigation instruments out there this one gets the most use. It's easy to use, accurate and well constructed. Would buy again in a heartbeat

Arrived with the corner chipped off. I glued it back on with super glue rather than go to the trouble of returning. Other than that, it looks good and works well.

Just as described. Weems has the best navigation tools.

Exactly what I needed for navigation rally.

I am learning to plot on a chart and this tool seems to be of very good quality. I would recommend

I purchased the Weems and Plath plotter following a bad experience with a Blundell Harling branded Portland Plotter, which had the poorest pivot accuracy possible. The W&P plotter is tight, repeatedly accurate and has far superior ergonomics and quality to the Blundell Harling. All markings are fine enough to quickly and easily align with the chart and course lines can similarly be easily and accurately measured. A superbe piece of kit and highly recommended for fast accurate plotting.