Using an Excel spreadsheet,
I constructed a Reinman sum approximation of the
integral calculus needed to calculate the Righting Moment of the Weekender
sailboat hull.
The math is not very complicated. First a cross sectional area model of the
hull at each station line was constructed on a one inch by one inch grid with the
stations all stacked on top of each other like a loaf a bread. The density of
the materials occupying each square at all the stations, times the one foot
length between the stations, were added together in each cell on a "stations"
worksheet. Then the cells were "rotated" around the center of gravity on
another worksheet using the standard ( x' = x cos a + y sin a,
| y' = -x sin a + y cos a ) equations for coordinate transformations in a
Cartesian plane. Finally, the densities of the materials in each of the rotated
cells were summed vertically with 62.5 lbs/ft^3 subtracted for any cells below
the inclined waterline. Each vertical sum was multiplied by the distance from
the center of gravity, and the products summed horizontally to determine the
final righting moment at that particular angle of heel.
I added a Spin up / spin down button to move the angle of heel by three degrees each time the botton is pressed to make gathering righting moment data easier for constructing the graphs.
Unfortunately, the button stops working when the worksheet is saved to disk, and the workbook is subsequently reopened.
It used to be that the button could be "reactivated" be popping into design mode, and editing the button properties. But now, the button has to be deleted and recreated from scratch to get it to work at all, and the button stops working the next time the workbook is opened.
I suspect that the button definition just gets "lost" in the spreadsheet. Two of the worksheets are large . 200 cells by 200 cells = 4000 equations each, and one of those sheets has a three stage conditional format, so the total is more like 20,000 multi-line equations.
I have protected most of the cells on the worksheets from inadvertent changes, but that has not caused me problems with buttons in the past.
What's wrong?