Weems & Plath 90 ParaLock Plotter
This GPS parallel rule, in a compact size, is particularly suited for use on modern small chart tables. The primary purpose of the Paralock Plotter is to enable the transfer of GPS positions rapidly, easily and accurately to and from any paper chart. The Paralock Plotter features three unique design concepts: a locking knob that allows the user to quickly plot a GPS position on paper charts, two sets of finger holes that enable finger tips to act as friction pads on the underlying chart, and, although shorter than standard size rules, the Paralock Plotter opens to the same width as conventional rules and therefore covers the same chart area. The most inventive feature of this patented device is the locking knob located at one of the four pivot points of the parallel plotter's cross-arms. This knob enables the two rulers to be fixed in any given separation which allows rapid determination of GPS position. The Paralock Plotter is only 7.25 inches long as opposed to the standard rule length of 15 inches, but its opening width is the same as standard rules. Placing finger tips in the twin finger holes allows easy operation of the rule and readily informs the operator if a slip has accidentally occurred while aboard a rolling or pitching vessel. The Paralock Plotter is made of sturdy, clear acrylic for maximum chart visibility. It has graduations so it can be used as a protractor to determine compass bearing. It also has a ruler across the bottom, making it is easy to take distances and transfer them to a mileage scale. The Paralock Plotter has all the features of a standard parallel rule but fits in a pocket and is easier to use. It is perfect for any boater who keeps track of latitude and longitude coordinates on a paper chart. Its compact, convenient size makes it the right tool for use on boats with limited chart space.