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Old 26-07-2010, 14:35   #16
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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.

P.S. Bilge 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.
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Old 26-07-2010, 14:43   #17
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after running aground .. a wing or bulb keel can become stuck or wedged in coral or rock.
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Old 26-07-2010, 14:47   #18
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Yeah Dockhead. You hit some great points.

I'm having a really difficult time deciding on my next boat primarily for the keel reasons - I'd want to sail in high lats and low lats. I want very fast speed but I want comfort.

Full Keel - traditional cruiser
Modified Fin Keel - performance cruiser
Fin keel partial spade; round sections - racer/cruiser
Fin keel full spade; round sections - racer/cruiser
Fin keel full spade; flat sections - cruising sled

I want them all...
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Old 26-07-2010, 14:54   #19
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with a full keel you'll get two very important things to a cruiser.

1. It ain't gonna fall off
2. You have a REAL bilge, not one of these 4" deep 'dustpan' jokes of a bilge
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Old 26-07-2010, 14:58   #20
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Dockhead, Thank you very much!

Now someone please give a post like that in favor of fixed keels. LOL

I really want to build a fixed keel only because it will be easier to transport over land after I'm finished. At the same time I don't want to limit myself because of that issue.
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Old 26-07-2010, 15:17   #21
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Originally Posted by SaltyMonkey View Post
Yeah Dockhead. You hit some great points.

I'm having a really difficult time deciding on my next boat primarily for the keel reasons - I'd want to sail in high lats and low lats. I want very fast speed but I want comfort.

Full Keel - traditional cruiser
Modified Fin Keel - performance cruiser
Fin keel partial spade; round sections - racer/cruiser
Fin keel full spade; round sections - racer/cruiser
Fin keel full spade; flat sections - cruising sled

I want them all...
Well you get into rudders, which is another can of worms . . .

Spade rudders are efficient for the same reason that long high aspect fin keels are -- aspect ratio. Some seaworthy heavy cruisers including Hallberg Rassey use them on some boats. Another is they are "balanced" -- they have hydrodynamic surface ahead of the axis of rotation which helps balance the resistance to turning and so acts like power steering.

I don't like them myself because of the risk of breaking them. Oysters combine modern bulb keel with a full skeg rudder, giving up any balancing for the sake of strength. That's probably would I would choose if I had such a choice. My Moody has a partial skeg and semi-balanced rudder -- a compromise, to go with her bulb keel. The Hylas 54 -- a legendary blue water boat designed by the great German Frers -- also has a bulb keel and partial skeg semi-balanced rudder, looking much like my Moody below the waterline. The strength issue is solved on the Hylas with an engineered weak spot which allows the unsupported part of the rudder to break off in case of hitting something.

So anyway, spade rudders don't necesssary go hand in hand with modern keels -- look at Oysters. Nor would I call my own boat a "performance cruiser" -- despite the bulb keel, she is a heavy long-distance blue water cruiser, which happens to have a certain turn of speed thanks to modern keel design, but whose main design value is seaworthiness and stability.
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Old 26-07-2010, 15:18   #22
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Lets not confuse wing keels with bilge keels:

Wing keel:




Origami version of the Bilge Keel:



Another bilge keel


Who designed this 2nd and 3rd boat? I like that!
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Old 26-07-2010, 15:29   #23
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Originally Posted by dreamer38851 View Post
Dockhead, Thank you very much!

Now someone please give a post like that in favor of fixed keels. LOL

I really want to build a fixed keel only because it will be easier to transport over land after I'm finished. At the same time I don't want to limit myself because of that issue.
I'll give you a powerful argument in favor of long keel boats -- they're cheap. That was the way a good boat was built before yacht designers figured out hydrodynamics and there are plenty of them around.

That's really the main question, actually. If you really need a heavy seaworthy boat and you have a limited budget, you might not have any other choice.
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Old 26-07-2010, 15:53   #24
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That's really the main question, actually. If you really need a heavy seaworthy boat and you have a limited budget, you might not have any other choice.

Budget is not really an issue. It's not like a can go out and buy a $500,000 boat tomorrow or ever. But I know I can build one hell of a 45' steel boat for less than $100,000. Maybe a lot less.

Now if I win the lottery during the building process (I dont play the lottery so it will be hard) who knows what I will do. LOL
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Old 26-07-2010, 15:58   #25
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Originally Posted by dreamer38851 View Post
Budget is not really an issue. It's not like a can go out and buy a $500,000 boat tomorrow or ever. But I know I can build one hell of a 45' steel boat for less than $100,000. Maybe a lot less.

Now if I win the lottery during the building process (I dont play the lottery so it will be hard) who knows what I will do. LOL
Hey, the odds of winning the lotto are essentially the same whether or not you buy a ticket!

Jim
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Old 26-07-2010, 16:11   #26
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Salty Monkey provided a great photo of a wing keel. I used to think they were faster to windward but found the deeper fin keel boat for boat can outperform them in the Catalina brand.
Can you imagine getting that thing stuck in the mud? Jeez!!

regards,
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Old 26-07-2010, 16:18   #27
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Fixed Keel?
Yes, that's what we've been talking about. We haven't even talked about swing keels or daggerboards and unless they are trailerables there is no point discussing them in your question concerning you want a large steel boat. If you want a boat that is transportable easily on a large flatbed then full keel is best.
regards,
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Old 26-07-2010, 18:17   #28
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Hey, the odds of winning the lotto are essentially the same whether or not you buy a ticket!

Jim
That's funny, and 99.99999% true!

Vic
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Old 26-07-2010, 18:21   #29
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Well, ok, on a flatbed bilge keel would be easiest but not on a big steel boat? Bilge keelers can weigh in on this one. I haven't experienced any large steel bilge keelers.
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Old 26-07-2010, 19:30   #30
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You wanna 45' boat that transports easily on land? What is that about? Are we talking weekend inland lake sailing here? If you need to move it, do it once. When it's wet, that's it, done.
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