Southerly yachts

[Fourbees]

I always look at the angle of vanishing stability (AVS) when wondering about ocean-worthiness. On the Southerly 110 it is a massive 160 degrees with keel down (and over 150 even with it up). The comparably sized Hanse 350 has an AVS of 133 degrees, the much bigger Bavaria 50 Vision only 121 degrees. Some RCD A boats have even less! I know what I'd rather be capsized in! Test sailed a Southerly 110 and she was steady as a rock in F7.

 

[lw395]

AVS alone doesn't tell you much. A log with a nail in it can have an avs of 179.99... degrees!
Also most are quoted without roller headsls, radar etc etc.
Its just one more number that needs to be taken into consideration with many other things.

 

[Fourbees]

I agree AVS is not everything, but it's an interesting point of comparison. I look at the whole of the stability curve as well; what I don't understand is STIX - is it any use as an indicator? Why don't all manufacturers quote it?

 

[lw395]

It's a shame that stix has come along and made it harder to compare new yachts against older designs. The old SSS number has its limitations too. I think the more interesting thing is the ability of a yacht to keep going (and make to windward?) in heavy weather, rather than its propensity to turn over. I don't know how you predict or measure this.

 

[boatmike]

You can't! There is no single mathematical formula that will predict a boats performance. Any hydrodynamicist or yacht designer will tell you there are always compromises. I have always been a traditionalist regarding monohulls and there is simply no alternative to a long waterline with long keel, fine entry, narrow beam etc for seagoing comfort and passage making. Such boats are however bloody horrible to steer around a marina, have cramped accommodation and no good at all at creek crawling. The Southerly is excellent at creek crawling, easy to handle, copious accommodation but will never hold a course to windward in a gale like a long keeler. As most people know, I now sail a cat. Thats not perfect either but I love it because an old fart of 65 like me has done his share of sailing to windward in gales of wind and likes his creature comforts. It's a compromise though.....