Instructions
Imagine your boat divided into slices of equal thickness (as if you were slicing a loaf a bread) and number the slices from one end of the boat to the other. Estimate the volume of each slice (multiply its height and weight by its thickness), then multiply the volume of each odd-numbered slice (except for the two end slices) by two and the volume of each even-numbered slice by four. Add the resulting figures to the volumes of the end sections to determine the total volume of your boat.
Add the mass of your boat to the mass of the air contained in the boat (air mass is 1.2 oz. times the boat's volume in cubic feet), and divide this figure by the boat's volume. Ensure this figure is less than the density of water (62.4 lbs. per cubic foot or fresh water; 64 lbs. per cubic foot for salt water); otherwise, your boat may sink. Use this density measurement to ensure your boat's density remains below that of water even when your boat is fully loaded.
Use your boat's volume to calculate the boat's displacement (the amount of water that the boat causes to move or shift when afloat). Multiply the volume of the portion of your boat below the waterline by the density of water (62.4 lbs. per cubic foot or fresh water; 64 lbs. per cubic foot for salt water). Subtract the boat's weight from its displacement, and divide this figure by five to determine the maximum safe load for your boat.
Measure your boat's sinking depth (the proportion of your boat will sit below the waterline). Multiply the density of water and your boat's volume, then divide this figure by your boat's length multiplied by its height and the density of water. Apply this information to the design and building of new boats to ensure that sensitive electronics or other elements are safely above the waterline, or working parts of the engine below it, when the boat is afloat.