Marine architects answer the questions that get asked of them. Because few captains ask them questions, the architects tend to be ignorant of the answers. If every boat owner/captain in the fishing fleet assailed their marine architects with the hard questions about icing and flooding, we’d probably have more answers than we do now. But few people challenge the stability data they’re given.
After the El Faro sinking, our company detailed a captain to ask our marine architect questions about survivability in case of various flooding contingencies on our boats. The captain was surprised to find the marine architect didn’t have the answers. Turns out stability and survivability from flooding aren’t the same thing, at least as far as some computer stability program are concerned. As with marine architects, computer stability programs answer a narrow set of questions. If you don’t ask more questions, the architects/programs will never come up with the answers.
Moreover, marine architects don’t like working with soft data, and the weight of the ice is not directly proportional to the thickness of the build-up. Icing can be spongy, or hard as cement, and it makes a difference in the weight. MAs don’t like to make guesses on this stuff, so there is a tendency to avoid the question.
RE; vessel icing; it’s always asymmetrical. It’s always heaver one one side than the other. Stability programs should have models in them that take into account heavy lateral icing on either sides, as well as very heavy icing on the bow.
I’ve dealt with severe icing as captain, and as a shoreside person dealing with the consequences of icing. One bitter lesson: iced-over tank vents are dangerous, at least on vessels 2500 tons and smaller. Once the tank vents ice-over you can’t transfer liquids to compensate for listing due to lateral icing.
If the vent runs through a freezer compartment, you’re not likely to get that ice out until the weather gets warmer, and even then reckon in days, not hours. The ice gets in the piping, aspirated in as sea-mist as the tank pants from rolling. Vents that run through non-freezer compartment are not going to be much different. I remember fueling a vessel with an iced over vent to the fuel tank. We blew a seam in the shell plating because of the built-up pressure.