Estimating Proportions

Choose a vessel introduced in any lesson in this program to draw to scale. It must be a vessel for which dimensions are listed. Use graph paper to make a drawing of your vessel’s profile. Here is a sample profile drawing.

Check the actual height and width of the vessel. If the vessel is taller than it is wide, turn your paper vertically; if it is wider than it is tall, turn it horizontally.Write the actual height and width of your vessel (as available) in the upper right corner of your paper. Do not make your drawing the same size as the vessel.

Determine the scale you can use to fill a large part of your paper with your drawing. For example, you might draw in 1/2 scale or 1/4 scale. This means you divide the height and width of your vessel by 2 (for 1/2 scale) or by 4 (for 1/4 scale). In a quarter scale drawing, the ratio of actual measurements to scale-drawing measurements is 4:1. Indicate the scale of your drawing in the upper right corner of your paper.

Begin by drawing a line down the center of the paper to represent the axis of your vessel. Calculate the proportional height of your vessel and mark off the top and bottom on your axis line. Compare the width of the mouth of your vessel with the height of the vessel. Mark off half the estimated width of the mouth on both sides of the axis. Compare the width of the foot or base with the width of the mouth. Mark off half the estimated width of the foot or base on both sides of the axis.

Next locate the widest part of the vessel. Estimate its location. Is it exactly in the middle? Higher? Lower? Compare the distance from the mouth to the widest part with the distance from the widest part to the foot or base. Make a mark on the axis to locate this widest part. Calculate the proportional width of your vessel and mark off half that distance on both sides of your axis line.

Compare the width of the mouth of your vessel with the width of its foot or base. Estimate and mark off the widths of the mouth and foot or base. Mark off half these estimated widths on both sides of the axis.

Next find the narrowest part of the vessel. Compare the distance above and below the narrowest part to locate it on your axis. Mark half the estimated width on either side of the axis. Depending on the complexity of your vessel you may want to locate and estimate other key parts of your vessel.

Draw a line connecting marks along one side of your vessel. Observe carefully how gradually or how abruptly the profile bulges in and out. When you have drawn your profile as accurately as you can, fold your paper along the axis. Place your folded paper on a light table or against a window. Trace the other half of the vessel.

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