What other options does one have besides GLM, and what are the pros and cons?

Other software is available for this purpose. Most of it is less accurate because GLM is one of the few that use geometrical vessel models directly. Most others are based on tables which are essentially approximations valid over limited ranges. In spite of this GLM, is typically less expensive for the software license. Model building and configuration costs vary according to the amount of time it takes. In some cases the time required to configure GLM is as little as two hours. This is because GLM uses the same data from computer files that many naval architects use to create trim and stability books.

Making spreadsheet is another option, which may be attractive if you have expertise with spreadsheets. It will take some time and will never be as reliable as a computer program designed specifically for this purpose. It will also lack the convenience and the graphics of a well- designed special-purpose program. In order to get the weights and free surface effects of tank loads, it will be a complex spreadsheet and complex spreadsheets are notoriously difficult to debug and maintain.

Doing nothing is sometimes an option but seldom a good one. Relying on experience and intuition about stability does not always result in safe loading.

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