Question: I recently had an interesting discussion about stability with a cruising yacht owner, and I thought this topic would be of real interest to any high latitude sailor. And I also suspect that you would have traversed this terrain long ago and have an opinion.
After the 1979 Fastnet race, the Joint Committee on Safety from Capsizing made the following recommendation: “The most significant contribution to the resistance to wave-induced capsize would be to increase the roll moment of inertia of yachts”. For a sailing yacht, adding mass at the top of the mast would increase roll inertia more than adding mass anywhere else (hulls are normally designed to support a given keel weight and depth, and adding additional weight to the keel is not recommended).
At the same time, various regulatory agencies and yacht racing bodies have firm guidelines, even rules, to ensure the highest possible Angle of Vanishing Stability (also know as Limit of Positive Stability). For a monohull, removing that same mass that we placed at the top of the mast, would have a more beneficial effect on the LPS than shifting the same amount of mass anywhere else on the boat.
Unless I am overlooking something, there’s contradictory advice here. To prepare a yacht to resist wave-induced capsize, do I favour an increase in roll inertia, or do I favour an increase in LPS? If I favour LPS, I would probably end up doing things that would diminish roll inertia (like keeping weight close to the deck).
Do you favour one approach more than the other, and why?