During the proposal stage of a project clients offend require "quick-n-dirty" design calculations. There quite a few free tools on the internet, which can be used for this purpose. We have assembled a few useful links to those tools.
Besides that we have developed our own online tool for the design of offshore lifting sets in accordance with the DNV 2.7-1 rules. It includes the dimensioning of the pad eyes, shackles, slings, masterlink and fore runner.