Cooking for 100 aboard ship?

Then you need General mess manual and cookbook for use on board vessels of the United States Navy from 1904. The Internet Archive edition is available in several formats, including Adobe Acrobat .pdf, plain text, and even a flip book that allows you to turn the pages as they appear in the printed edition.

And it's not all beef broth and boiled oatmeal; in 1904 the sailors could still have plum duff:

Soak 25 pounds of stale bread in cold water and drain dry.
Add 25 pounds of sifted flour, 5 pounds of suet chopped fine, 3
pounds of raisins, 5 pounds of sugar, 4. pounds of currants, 2
pounds of prunes, 3 tablespoonfuls of salt, 1 teaspoonful of ground
cloves, 1 tablespoonful of ground cinnamon, and 1 wineglassful
of vinegar, and mix all thoroughly with cold water. Turn the
bags inside out, drop them into boiling water, render out slightly,
and drop into dry flour, dredging them thoroughly. Turn the
bags flour side in and fill them with the pudding, securing the
opening firmly, drop into the copper in which water is boiling
and cook for at least two hours. If there is sufficient time, the
pudding will be improved by boiling three or four hours.

The 1902 edition is also available online from the Navy Department Library, but only as a single web page, which takes a very long time to load.

The Internet Archive has other cookbooks; searching for cookery will bring up screens full, as it appears in many titles of older cookbooks as well as being the current Library of Congress subject heading term.