What weighs 10,000lbs is six feet tall and is grey all over? Whatever it is it doesn't sound very attractive unless of course you love sailboat designs which I do. The answer is the deep keel of the Sabre 456. We had one in the yard just before Christmas and it shipped with it's hull to San Diego, California where it is now being attached and the boat being readied for the January Boat Show.
Keel design is all science but to my eye it's also art. The profiles created by Jim Taylor for this and all of our current designs are truly beautiful and what makes this huge chunk of lead so amazing is the way that it moves the boat through the water. To the unknowing observer sailboat keels just keep the boat upright and that is of course true. But their shape makes the boat sail to windward and resist side slip too. It provides lift just like an airplane wing. Modern keels are an amazing piece of technology.
I have keel discussions a lot. One thing I have learned from 30 years in the sailboat business is that old books don't go out of print so that expert advice given in 1980 is still out there today. The problem is that old books don't adjust for technology. I am frequently asked to compare shallow versus deep keels and that's pretty easy these days because shallow keels, due to technology and the advancement of design, can perform very well for the typical sailor. The center of effort is about the same since the keels typically have additions in the form of wings or torpedoes on the bottom. Most (and I mean >99%) of all sailors would not be able to steer their boats consistently enough to adjust for the tiny difference in pointing angles of today's designs.
The sole exception is that if a boat is going to race most days and if the water is always deep enough then go with the deepest keel that you can. There will be a tactical advantage to the deeper keel that would help to defeat a competitor who could not point as high. So if you are in this league then go deep. Otherwise let your home port, your cruising grounds and your docking situation be your guide.