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  #31  
Old 03-17-2013
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Re: Modern design + full keel?

I am looking at a boat now with a drop keel. What do you think of these , I don't see any of the modern boats with them.
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Old 03-17-2013
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Re: Modern design + full keel?

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I am looking at a boat now with a drop keel. What do you think of these , I don't see any of the modern boats with them.
Drop keels have a place also. I believe J-boats builds a version, as do Jeanneau, Beneteau in the smaller sizes, ie under 35' or so. Hake is another builder of ALL CB style boats. Ovni?!?! is also a builder, as are numerous other European builders. Generally speaking, there are not too many north american modern design builders.

marty
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  #33  
Old 03-17-2013
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Re: Modern design + full keel?

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Originally Posted by John B View Post
I am looking at a boat now with a drop keel. What do you think of these , I don't see any of the modern boats with them.
When you say "drop keel", I assume you are not talking about a centerboard. There are 2 basic types of drop keels: swing keel and daggerboard. There are a number of swing keel boats that have been made over the years, but when you get into the 30+ ft range, the Clearwater 35, Seguin 40, Feeling 416 DI, and Southerlys come to mind in the swing keel genre. The Hake designs represent the daggerboard option. I believe the Southerly and Hake boats are available new, but the Clearwater and Seguin are not in production and I don't know about the Feeling.

FWIW, I own a Clearwater 35, which I acquired 17 years ago, primarily for its extreme shoal draft (1' 10" with keel and rudder retracted). With this kind of draft, the anchorages are bigger, more slips are availble, you can take shortcuts others can't, and you have more gunkholing options. There are no performance compromises when the keel is down. In fact this boat is less tender and more weatherly than most boats in her size range.

The real compromise is in reduced interior volume--although I have 6'3" headroom--and a main cabin that has an unorthodox layout to accommodate a keel trunk that extends to the coachroof. You might also consider that the swing keel and swing rudder add complexity (and therefore added initial cost) with the potential for additional maintenance.

A daggerboard in the shape of a fin keel with a ballast bulb (e.g., Hake) may provide a more efficient foil than my swing keel, but would likely sustain more damage in a hard grounding than my keel (which would swing up on impact). Not to pick on Hake: a hard grounding with a fixed keel might be worse than a hard grounding with a daggerboard, depending on the trunk design. A stand-out advantage of either swing keel or daggerboard is that you could--in most cases--self-rescue in the case of a hard grounding by retracting your "landing gear".

IMHO, you would consider such a boat if you really needed the shoal draft, otherwise you ought to keep it simple. For the much of the East coast and the Bahamas, it makes sense, but perhaps not so much on the left coast.
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Old 03-17-2013
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Re: Modern design + full keel?

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Originally Posted by fallard View Post
When you say "drop keel", I assume you are not talking about a centerboard. There are 2 basic types of drop keels: swing keel and daggerboard. There are a number of swing keel boats that have been made over the years, but when you get into the 30+ ft range, the Clearwater 35, Seguin 40, Feeling 416 DI, and Southerlys come to mind in the swing keel genre. ...
I don't know very well your boat but for what I have understood, like the Southerly, it has about half of the ballast on the keel half on the interior.

There are another type of swing keel that is used on some recent sailboats, one that has all the ballast on the keel, being the keel also more full at the bottom to lower CG. Those keels also maximize ballast by having normally a big draft when down. A 35ft can have a draft with the keel down of 2.80m. That gives it also a very good upwind performance.

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  #35  
Old 05-05-2013
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Re: Modern design + full keel?

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Originally Posted by Jeff_H View Post
And if we are going to be technical about it, an Island Packet is a very long fin keel with a post hung, spade rudder. And I am not sure that I would call that a modern boat. Jus' say'n




But for the most part, I don't know of any boats that have a modern hull form and rig but with a full keel. There are quite a few boats with traditional looking hulls but with modern keels and rigs.

In reality, boat designs operate as a system. Modern hull forms have comparatively little drag and so would not work well with a high drag keel or rig. You would end up with a pretty foul craft with all the liabilities of both schools of thought but that did nothing very well.
Actually, the latter is not true. One of my boats is very much like a classic moth, in design. It's 10'. It was made in 74 and, when I got it, it had a boomed lateen. It was not the original sail. I designed and made a boomed sprit rig for it. It sailed just as well as my Holiday20, which has a Bermuda rig.

Recently, I decided to try for a full keel design so I could get rid of the DB trunk and have more space for comfortable sailing. After a number of designs, all of which were successful, I went from a fin keel to a real modified full keel...meaning that the forefoot is cut away, rather than being from the bow to the stern. The boat sails like a champ. I have no trouble coming about. It points as close as with the DB. But, it also had some benefits, besides additional cockpit space and shallower draft. The boat tracks better in heavy chop and wakes and gusty conditions. In addition, the boat, which is fairly tender, is not nearly so nervous in gusts and it is safer and more comfortable to sail if you get caught in a squall. It doesn't heel nearly so much or so violently when subject to gusts or heavy wind. And it hasn't slowed her down. The DB was 2.5% of the sail area. The shallow full keel is only 4% of sail area, which is often the recommended percent for the underwater foil, anyhow. I have no increased leeway. Now, I do not race around the buoys, so I will say a racer might find the graceful arc she makes, when coming about, less than ideal. However, when sailing normally, you should come about gracefully instead of slamming the tiller over. That's how I learned to sail. It kills your way to come about in that manner and is really just a racer's tactic. I am always getting comments on how well she sails, by other sailors that see me. No one expects her to point so well or handle heavy winds so well. And everyone is amazed how well she sails in airs so light you can't tell there is a breeze. In addition, se tracks better, when rowed ( yes, I put oar locks on her ), with the keel than the DB.
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Re: Modern design + full keel?

I think one big problem is that people look at boat design as a bunch of unrelated elements. Traditional sails only get used on older hull designs. Full keels are only used on older hull designs. Then they try to compare these elements as if all things are equal. But that really is like comparing apples to oranges. No matter how good a sprit sail may be on all points of sail, if the boat it's on has a less efficient hull design, it's not fair to compare it to a Bermuda on a racing hull. Similarly, full keels only get put on displacement boats, often with a broad, full bow, as a rule. My boat has very little draft, outside of the DB or the, new, full keel. It is slender. It has a very narrow entry and, then, after the middle where the beam is greatest, it tapers, a bit, to the transom. It is a planing hull, with the hull, aft, being nearly flat. When I sail to wind, I move me weight, even with the middle of the boat, where the DB used to be. This raises the transom out of the water, reducing wetted surface, in the rear, and brings the narrow bow deeper in water. If you really look at the shape the hull is presenting, to wind, the hull is helping the keel to avoid leeward motion. In fact, if I pinch her, I can sail a little closer than 45 degrees to the wind, especially in a good breeze. I have always kept my weight to windward, when tacking, until the bow has passed the eye of the wind and is actually on the new tack, because she is light and doesn't shoot as well as a heavier boat. I still do this when tacking. It works well with the full keel.
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Re: Modern design + full keel?

One thing I forgot to mention, and should point out, is that my rudder is hung off of the transom, as is normal in a dinghy, and the keel stops at the waterline, when the boat is sitting on the water without weight leaned towards the stern. This means that, although the keel travels nearly half of the water length, there is a foot between the end of the keel and the beginning of the rudder. This may have some effect on how the keel functions. It may give it some of the properties of a shallow fin keel, since, most often, full keel boats have the rudder mounted on the keel.
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Old 05-05-2013
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Re: Modern design + full keel?

and what is that modern boat of yours with a full keel that is able to do a little better then 45º against the wind?

and regarding this:
Quote:
Originally Posted by captain jack View Post
Actually, the latter is not true.
can you be a bit more specific about what is not true:

this:" Modern hull forms have comparatively little drag"

or this: "and so would not work well with a high drag keel or rig"

or both?
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Last edited by PCP; 05-05-2013 at 06:40 PM.
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Old 05-05-2013
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Re: Modern design + full keel?

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Originally Posted by PCP View Post
and what is that modern boat of yours with a full keel that is able to do a little better then 45º against the wind?
PCP is right.

FWIW, I own a boat with a (real) full keel - and there is no way on this planet it could ever hope to perform as well as a cut-away-forefoot keel and especially a fin keel!

...but that's not why I own a boat with a (real) full keel and not why they are built like that in the first place.
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Re: Modern design + full keel?

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Originally Posted by Hartley18 View Post
PCP is right.

FWIW, I own a boat with a (real) full keel - and there is no way on this planet it could ever hope to perform as well as a cut-away-forefoot keel and especially a fin keel!

...but that's not why I own a boat with a (real) full keel and not why they are built like that in the first place.
Hartley, don't take me wrong there are great boats with a full keel and even if today it is difficult to find a baldly designed modern boat, there are plenty of fin keel boats badly designed.

But this thread is about modern designed boats with a full keel, or better about the nonexistence of them.

Jeff explained pretty well why they are not an option in contemporary boat design.

Regards

Paulo
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