If you search the archives
you'll find a lot of information on this.
Keels like sails
and like airplane wings depend on aspect ratio for efficiency. That's why racing
boats have very narrow sharp long keels.
An efficient keel
-- that is, one with a high ratio of length to its width --will let you sail fast, and will let you sail close to the wind
. Sailing close to the wind
is a really important quality in a sailboat.
An inefficient keel
-- that is, a long shallow one -- will be slow and will make it hard to make progress upwind, which can be deadly if you ever need to sail off a lee shore.
A long keel boat is a bit like a square-rigger. If the wind's not just right you wait or motor
. In our old boat we motored at least 70% of the time. In the new boat we sail 90% of the time. That's because, unlike the old boat, we (a) move in light wind (despite more than 20 tons displacement); and (b) we can make useful miles in any direction, including tacking directly upwind, because of how much closer to the wind she sails
The average long keel will track better downwind than the average fin keel. But the length of the keel has little to do with pounding or other kinds of stability. Pounding is a function of forefoot shape, not keel design.
As Salty said, long keel boats are very awkward to maneuver in tight places. They generally don't back up straight, either.
I don't have much use for long keels, personally, and I have more than a decade of sailing on a long keel boat. A fin keel boat can be just as seaworthy
as your average long keel boat if it's built for it. Seaworthiness comes from displacement
and forefoot shape and underbody shape aft and ballast ratio, not from keel design. Some fin keel boats are designed for speed and interior
space without regard to other qualities and are not too seaworthy
, but others are designed with different values in mind and are just as seaworthy as any long keel boat. It's no coincidence that Swan, Hallberg-Rassey, Oyster
, Malo, Discovery, and the other top yacht builders build nothing but fin (or bulb) keel boats.
When I went from a long keel boat to a bulb keel boat last year it was like stepping out of a 1962 Dodge Dart with three on the tree and a slant 6 motor
and into a 2010 BMW with a V12 and a seven-speed transmission
. Hard to describe the difference, it is so enormous; actually the difference was more than in my car analogue. And the long keel boat was a very highly respected one, known especially for its seaworthiness and seakindliness.
If you want to go to high latitudes you want a strong, heavy blue-water boat, not a coastal flyer. These are available with modern keels, although they are quite a bit more expensive than the coastal type.
The modern keel on such boat will give you another safety
advantage -- you can make miles and get out of the way of weather
to a much greater extent, than you can in long keel boat, and you can keep going in rough conditions.
OK, that's the case for fin keels. Let the flames begin.
keels have also been mentioned here. Under sail they perform generally like long keels but have the enormous, humongous advantage of being completely unafraid of being dried out. So for coastal sailing in tidal places they really can't be beat -- they open up all kinds of places you can't get to in other kinds of boats.