How to Measure for 3 Point Dimensioning

A step-by-step guide to accurately measure non-standard dimensions for a net opening.

Instructions

Diagram

ⓘ Overview

3 Point dimensioning is useful for establishing non-standard dimensions which are commonly presented on multihull net openings. By triangulating measurements one is able to recreate any geometry. In this process, one lays out enough points to on the edge of the boat opening such that one can interpolate the overall dimensions from the points laid out. We would recommend laying these out using masking tape and writing an “X” and numbering the points as they go. Then make a sketch of the opening showing where each point is located on the sketch. Also, take a picture of the net from as close to overhead as possible ensuring to get all the edge of the boat opening. This allows us to see the layout points and better interpolate between the measured points. A typical net will take 15-20 points, with a very complex net possibly requiring more. The points should be placed in all corners, at all inflection points (where a curve changes direction), and should be placed in at least 2 locations along any radiused curve (such as a hull curve). The person measuring then picks 3 points roughly evenly spaced around the opening and labels them A, B, & C…these will be the points dimensions to all the other points are pulled from.

1. Lay out all points

Lay out all points. Use masking tape and a sharpie to number and put an “X” at the point to ensure measurement to the exact point can be repeated. Make sure the point is at the net-side edge of the boat opening (eg, on the inner edge of a lacing track, or inner edge of a lacing rail) as we will be offsetting the net lacing gap from this point.

2. Make a sketch

Make a sketch of the layout showing all numbered points in their approximate location on the sketch.

3. Take a picture

Take a picture of the entire opening so that we can see the general layout.

4. Pick 3 points

Pick (3) of the numbered spots approximately equally spaced out and label them (A), (B) and (C). I would suggest two adjacent corners and roughly mid-point of the opposite side. The exact location of them does not matter.

5. Take measurements

Take measurements from point A to all other points. Ensure the tape measure is measuring from “X” at point A. You want these measurements to be within 1/8” if possible, although within ¼” is typically workable. If you have a helper this is much easier, however, if you can anchor the tape measure at the point you can do this alone. The dimensions are to be entered at each point in the form (Dimension from A, Dimension from B, Dimension from C). If possible, please note the dimensions in just inches). For example, on the diagram tab point 1 is labeled (0”, 78-3/8”, 63-1/4”) because it is 0” from point A (point A is on point 1), 78-3/8” from point B, and 63-1/4” from point C.

6. Repeat measurements

Repeat this from point B & C. When you are done you should have something that looks like the first picture on the diagram tab.

7. Scan and send

Scan and send your sketch with the dimensions and also attach the picture(s) of the net.