Why do you say this? It is true that stability curve makes no sense but a value of about 130º or even superior for an AVS is pretty good, the hull design has nothing new or interesting but it seems adequate to me and the boats are heavy contributing for the overall stability. Besides they sailed extensively offshore with a good proven record regarding seaworthiness.
So, why do you find them dangerously unstable?
Good to see some feedback
I guess I should have said could be dangerously unstable.
Tad's estimate for 130 degrees was without the cruising load and added equipment that tends to accumulate on a boat and that reduces stability considerably more than the half tanked minimal hull consideration, he had mentioned that to Brent before. It could reduce the limit of positive stability easily by 30 degrees. An inclining test on a cruising boat with all gear extant and in position is the real test. It's one you'd expect Brent would really want to know about having mislead so many of his clients for so many years telling them the design is stable to almost the full 180 degrees.
I've done a lot of stability studies on sailboats and the inclining test is often a real eye opener for the owner. The published stability curve from production boats is an ideal and they may not even make allowance for the gear the boat is actually sold with, let alone the owners additional cruising gear. Some designers work up all sorts of extras in their weights study some just treat it like a bare boned racing boat.
ISO STIX labelling is becoming something of a standard requirement but what you think of STIX is another matter and many designers aren't happy that it accurately reflects the seaworthiness of a sailboat.
The longer a boat the bigger the sea it can cope with, with a lower risk of being inverted, and the stability can be reduced accordingly. Considering Brent has common designs for 27 to 36 feet and more recently a 40 footer and he promotes them for high latitude offshore sailing then stability is the real key to safety.
Here's a good illustration of the 98 Hobart fleets inversions and their length relative to limit of positive stability superimposed on the UK requirements for sailing boats carrying public.