Safe Loading — Subpart C

Calculation of Maximum Displacement

Look carefully at Figure 3-A. You have measured the net dimension between the float-plane and the boat on each of the vertical lines at each station; now enter them in the blank form located in section 4.1. Then enter the beam at each station. Remember this is the full calculation beam and not the half-beam. Enter the calculation length (L). Figure 4 shows a detailed look at the manner in which the stations A-A, A, B, C and D are laid out and measured.

FIGURE 3 A - Determination of Boat Displacement - Detailed

We are now ready to calculate the displacement in pounds. In Figure 4 we have a worksheet to compute the Simpson’s Rule formula and arrive at the cubic capacity which, when multiplied by the weight of a cubic foot of water, will give us the boat’s displacement below the float-plane. It’s a good idea to make extra copies of these blank forms. Fill in the values measured and run the equations to get cubic capacity.

When you finish the calculations on these forms, the displacement of the boat measured inside a mold has been determined. This figure, known as the maximum displacement, is used to calculate the maximum weight capacity.

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