`Download BOX.GF for use with this example.

proj BandArea
read box.gf  `length=50m, beam=20m, depth=10m
`only override the Shape Factors if you want actual area instead of effective area
comp * /sf:1  `GF needs to be reread to restore original SFs

`define wind heeling moment with zero pressure gradient
variable pressure=0.1
wind (pressure) {pressure}
\pressure={ pressure:2} {wunit}/{lunit}^2
hmmt wind /band:0.02

macro bandarea
 \\--Depth={depth}--\
 hmmt report
 \system variable windf={ windf:2} {wunit}
 variable area
 set area={windf} div {pressure}
 \             band area={  area:2} {lunit}^2
 set area=10 minus {depth} times 50            `formula specific to BOX.GF at trim=0
 \           actual area={  area:2} {lunit}^2
/

tr 0
dr 4.0
.bandarea
dr 4.05
.bandarea
dr 4.1
.bandarea