Small Boat Keel Types

[N4061]

Question for the experts related to keel types. I'm learning different keel designs serve different purposes and the more keel in the water results in more water surface (drag) and likely slower speeds. I also understand a full keel may be less responsive. So far so good?

If looking for a smaller boat (under 22') to learn and sharpen the sailing skills what are the pro's and cons of the Cat style designs. From what I see they offer largest beam to LOA ratio (2:1) but you have to have a keel that is movable (up / down) which takes up space in the cockpit. They use large rudders and a single sail up front.

Are these boats harder to sail than say an Aileron 20' (long and skinny with a smaller keel) and beautiful to look at?

John

[zstine]

Keels: In general I think of a keel as a foil having 'ballast' which serves 2 purposes, balancing the sideways forces from the sail to allow the boat to track forward and providing righting moment. I generally don't consider non-ballasted centerboards and daggerboards as keels, but that's semantics. Length to width Aspect Ratio (where length is vertical) is the primary measurement that dictates performance of a keel. Full-length keels being very low aspect ratio generally perform poorly to windward and add a lot of drag compared to a deep-thin high aspect fin keel you see in high performance boats. High performance keels will pair high aspect with a lead bulb to lower the ballast CG and increase righting moment.

Cat boat vs Aileron 20... First a cat-boat is a style of rig and hull that doesn't have a defined keel style. Traditional cat boats are open deck, wide beam, shallow draft. The movable keel of a catboat is called a centerboard and many are not ballasted keels. So many of the Catboats, if knocked down, are not self righting. However, there are 'cat boat's' that have fixed ballasted keels, such as Nonsuch. Cat boats only have a mainsail and I suppose are easier to sail than an Aileron in that respect, but they won't sail into the wind nearly as well as the Aileron, so making way to weather may be harder.

An Aileron has a ballasted keel and is self righting. So from that perspective of having to balance the heeling moment with moving crew weight, the Aileron is more forgiving than a traditional centerboard catboat. Of course a centerboard is easier to trailer, if you plan to do that. An Aileron would be harder to get on a trailer with the fixed keel. They are very different style boats.

If you intend to learn to sail on this in order to 'move up' than I would suggest a sloop rig. They are the most common rig in smallish boats and perform well to weather. If you are trailering the boat or operating in shallow water, then a centerboard may be beneficial. Some centerboards are housed in a stub-keel that is ballasted and self-righting or the boat has lead in the bilge area to provide righting moment... not that there's anything wrong learning on a sailing dinghy like I did.

[N4061]

Thanks for the quick response. I had to look up a few words but got it. Sound like I will lean towards an "Aileron" style boat and not worry about trailing it. Below is what I found on-line:

A sloop is a sailboat with a single mast typically having only one headsail in front of the mast and one mainsail aft of (behind) the mast. Such an arrangement is called a fore-and-aft rig, and can be rigged as a Bermuda rig with triangular sails fore and aft, or as a gaff-rig with triangular foresail(s) and a gaff rigged mainsail. Sailboats can be classified according to type of rig, and so a sailboat may be a sloop, catboat, cutter, ketch, yawl, or schooner. A sloop usually has only one headsail, although an exception is the Friend