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  #401  
Old 04-21-2012
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Re: Full or fin keel?

Some of the pro fin posts use the extremes of the full (and its related cons) to support the pros of their fins (with out mentioning its related cons).
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  #402  
Old 04-21-2012
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Re: Full or fin keel?

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Originally Posted by wolfenzee View Post
Some of the high performance fins....you can barely look down long enough to pick up your coffee with out going off course. My full keel was outfitted with a self-steering vane which was removed because the boat will sail for days on end with a lashed tiller.

My boat is 30loa, 25lwl, 8'9"beam, 5' dafft about15,000lbs....deepest point is at the base of the rudder post (transom hung rudder with slight rake to transom).
This thread is not a about a particular kind of fin keel versus a heavy long keeler. Long keelers are only heavy because at the time they were designed there was not available technology to make them light. Today you can design and build a light full keeler. The reason they do not exist is because it does not make sense. You can design an overall better boat with a fin keel or midified fin keel for any kind of sailing.

Again, this is not about light boats versus heavy boats not about beamy flat bottom boats against more narrow boats with a lot of rocker. You seem to associate fin keelers with racers and performance boats and your comparisons are always between a boat like yours or an heavy full keeler and a light flat bottom race derived performance cruiser. That makes no sense.

As I have said I think that there is not a right boat fore offshore work but several seaworthy types adapted to different sailors and different types of personalities and sailing tastes. For the ones that favor the type of motion and the slower ride of a medium-heavy boat there are plenty offers on the market, narrow and beamy...all with a fin or modified fin keel, or at least all that have a modern designed hull and not a design based on some 40 year's old sail boat.


Even the guys that love so much classic boats that have modern boats designed according their lines (narrow and with a lot of rocker) and have the money to go to a good NA to make their dream true end up with a classic boat with a fin keel and a spade rudder just because it is a better technical solution and I don't mean for racing but for overall sailing.

I love traditional boats and old boats and it make all sense to preserve those boats and even in some cases to build replicas, but not because they sail better. Just because they represent the best it was made at that time. They all will certainly offer great sailing....but obviously not an overall better sailing than a modern designed boat, otherwise modern boats would only be improvements of those designs and not completely different boats.

Regards

Paulo
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  #403  
Old 04-21-2012
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Re: Full or fin keel?

As an ex archer, I have trouble with the feathers on the end of the arrow analogy. The feathers are surrounded fully by the medium they are passing through, it would be a great analogy for a submarine.

I do understand the gain in leverage by moving the rudder to the stern. But in this case the "arrow" is skimming the surface, with only one feather in the medium. And many times I have watched gusts cause boats with stern mounted rudders to lift the rudder out of the water as they ahem - politely - "round up" or what I would call broaching, something I hate. With the rudder lifting out of the water they have no helm control at all. The deep rudder on the end of a full keel does not lift so easily.

That is my personal observation. But what I wonder is, doesn't the turbulence from the fin disrupt the water enough to lessen the effectiveness of the rudder even when it is fully submerged? Isn't all design lift on high aspect foils based on an undisturbed fluid? Don't planes drop in turbulence? Or just the ones I'm on :-)
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  #404  
Old 04-22-2012
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Re: Full or fin keel?

As I understand it, the foil shape of the keel provides the actual lift when the boat is properly sailed at the correct angles and leeway (in relatively undisturbed water - but in reality all of this is working in very non linear 3D so 'undisturbed' is a probably a strong assumption)... the foil of the rudder is a low drag shape but the additional 'lift', if any, is more a function of the slight rudder angle with the optimum weather helm at play.

And I think most broaches happen because the rudder stalls, initiating the broach, after which the rudder may indeed be 'lifted' out of the water - but the damage was done before that. Some fin keelers, esp from certain eras, were indeed 'broach machines' but usually mostly when over-pressed. We've owned a few of these styles of boats and with careful sail selection and decisions, along with course selection, we had few incidents despite sailing over 20 years in a notoriously heavy wind area.

There's lots of room for both camps - I appreciate the saltiness of the full keelers of all sorts, but personally appreciate more the attributes of a lighter, more agile fin keel boat for our region and sailing habits. Quite likely in terms of overall sensibility the various compromises like the famous Brewer Bite, and the modified long chord fins from Bob Perry and the like make the most of both points of view.
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  #405  
Old 04-22-2012
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Re: Full or fin keel?

As this is in the "cruising @ liveaboard forum" rather than a performane and raceing forum....the tracking ability and smoother handling of a full would be preferred.
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  #406  
Old 04-22-2012
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Re: Full or fin keel?

PCP

I love traditional boats and old boats and it make all sense to preserve those boats and even in some cases to build replicas, but not because they sail better. Just because they represent the best it was made at that time. They all will certainly offer great sailing....but obviously not an overall better sailing than a modern designed boat, otherwise modern boats would only be improvements of those designs and not completely different boats.

You are just being silly with comments like that. What on earth does "sail better" mean?

For me, its a long keeled boat every time. I have owned one for 20 years, a Union Polaris 36. If it sank (heaven forbid), I would buy another one.

I have sailed on deep fin boats. They are faster, they point higher, but they are not for me. They don't "sail better" for me. They never will. All that helm correction and tweaking? You can keep it.

Give me a 36 ft boat, 22,000 lb displacement, and a full keel cast into the fibreglass. You can have your deep fin keels, and bolt them on, and you can point higher and go faster. You can even have one of those lovely spade rudders too.

As for "Sail better"?... for you, yes, but not for me, no matter when it was built.
.

Last edited by Rockter; 04-22-2012 at 02:27 AM.
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  #407  
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Re: Full or fin keel?

Quote:
I have sailed on deep fin boats. They are faster, they point higher, but they are not for me. They don't "sail better" for me. They never will. All that helm correction and tweaking? You can keep it.
I owned a Beneteau 393, a very conventional fin and spade. with a bit of careful tweaking with the sail balance, she would sail upwind without a hand on the wheel.

Sea kindliness, etc etc has nothing to with long keels, its a function of the boat design , weight and the way they are driven. Long keels existed because that was the only way the vessel could be built. The technology did not exist to attach a heavy structure to a wooden frame.

Modern fin keels ( which itself is a broad family) are proven better hydro-dynamically and computer modeling has shown that decisively. Id argue that encapsulating a keel is irrelevant in whether its a fin or not.

Yes , I like old cars and old aircraft too. But I don't persist in arguing they are better then the modern computer designed versions.

If you like full keels ( i don't know where anyone is going to buy one new these days) that fine. No doubt you like old Jaguar cars too. But accept that modern naval architects with access to infinitely more knowledge and computation modeling do actually know what they are doing.

modern boats do "sail better", they are more efficient, faster in a given wind strength, more agile, more controllable ( try surfing) and significantly stronger per llb. Modern technology allows such vessels to maintain high speeds and punch through weather, that has older designs breaking up and so they heave to. Yes this is at the extreme end of the technology, but its shows where the trend is and what its capable of.

Upto the late 60s, the concept of taking a small boat across oceans, was generally regarded as madness, undertaken by a few lunatics, some actually knighted for it. This was because the basic craft, of the day ( and hence its design) simply wasn't up the job, and required enormous maintenance and some skill to achieve these tasks. Small boat design evolved from small coastal fishing technology of the day, such technology never envisaged crossing oceans.

Today anyone in a reasonable well fitted out "plastic fantastic" can cross oceans and circumnavigate. why, primarily because the basic technology in the boat is stronger, more resilient, and efficient. Arguably the sailing skill of the owner is less, but the boat makes up for it.

A boat is a machine, technology moves forward, something designed years ago , simply cannot be better or even as good, the knowledge simply wasn't there. Boats like anything else are a product of continuous evolving technology, there is no historical "sweet" spot.


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Last edited by goboatingnow; 04-22-2012 at 06:48 AM.
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  #408  
Old 04-22-2012
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Re: Full or fin keel?

Quote:
Originally Posted by Rockter View Post
PCP

...
You are just being silly with comments like that. What on earth does "sail better" mean?

....
.
This has been a civil discussion and calling me silly doesn't add any value to your point of view and I prefer not comment on about what it says about you.

Sailing better is sailing better, faster in all points of sail, better tracking ability better pointing ability, same sea motion (for the same type of hull and weight), more light on the helm, more responsive, turning better under engine on forward motion and incomparably better on backward motion, in one word, sailing better.

Regards

Paulo
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Re: Full or fin keel?

PCP :

This has been a civil discussion and calling me silly doesn't add any value to your point of view and I prefer not comment on about what it says about you.

Sailing better is sailing better, faster in all points of sail, better tracking ability better pointing ability, same sea motion (for the same type of hull and weight), more light on the helm, more responsive, turning better under engine on forward motion and incomparably better on backward motion, in one word, sailing better.


Then that's fine for you. Maybe in your world, downwind in a big Atlantic swell, day-after-day of it, your boat design is better for you. And you like deep fin keels and you like the idea of them being held on by bolts, and you like the cantilever stresses imposed on a spade rudder. And you clearly like helm sensitivity.

I don't.

No, give me a long keel, give me a keel-hung rudder, and cast the keel into the GRP so I don't have to worry about those keel bolt things. And give me a ship that is slower to respond to sea and helm.

That's for me.

Yea, because it "sails better" for me.

If anyone tells me otherwise, then they are being silly.
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  #410  
Old 04-22-2012
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Re: Full or fin keel?

Quote:
Originally Posted by Rockter View Post
PCP :

[I]This has been a civil discussion and calling me silly doesn't add any value to your point of view and I prefer not comment on about what it says about you.

Sailing better is sailing better, faster in all points of sail, better tracking ability better pointing ability, same sea motion (for the same type of hull and weight), more light on the helm, more responsive, turning better under engine on forward motion and incomparably better on backward motion, in one word, sailing better
.[/I]

Then that's fine for you. Maybe in your world, downwind in a big Atlantic swell, day-after-day of it, your boat design is better for you. And you like deep fin keels and you like the idea of them being held on by bolts, and you like the cantilever stresses imposed on a spade rudder. And you clearly like helm sensitivity.

I don't.

No, give me a long keel, give me a keel-hung rudder, and cast the keel into the GRP so I don't have to worry about those keel bolt things. And give me a ship that is slower to respond to sea and helm.

That's for me.

Yea, because it "sails better" for me.

If anyone tells me otherwise, then they are being silly.
Responds to helm is the same as being sensitive or at least it was what I wanted to say.

Regarding preferring a full keel to a fin fin keel or modified fin keel bluewater boat based on the fear of losing the keel that makes no sense. There is not a single case of a bluewater designed fin keeler boat that has lost the keel, I mean boats like Halberg Rassy, Najad, Malo, Passport, Vailant and many others that are designed thinking in offshore extended sailing.

Regarding that thing of calling me silly for stating the obvious, as you can see by the post bellow I was not trying to say to anyone what kind of boat they prefer to sail. Some even prefer to sail XV century Caravela replicas:



and they would have more pleasure sailing then than sailing a modern boat. That's more than OK to me and I have already said that.

But I am pretty sure that they would not say that they prefer to sail a XV century old boat because it sails better than a modern sail boat. That would mot make sense as it does not make sense saying that one prefers a long keel 50 year's old design sailing boat because it sails better than a modern offshore medium height cruising boat and that is not going to change by the fact that you insist in call me silly.

Quote:
Originally Posted by Rockter View Post
PCP

I love traditional boats and old boats and it make all sense to preserve those boats and even in some cases to build replicas, but not because they sail better. Just because they represent the best it was made at that time. They all will certainly offer great sailing....but obviously not an overall better sailing than a modern designed boat, otherwise modern boats would only be improvements of those designs and not completely different boats.

You are just being silly with comments like that. What on earth does "sail better" mean?...
As for "Sail better"?... for you, yes, but not for me, no matter when it was built.
Sailing better is not a fantasy but an objective thing. As I have said sea motion and boat behavior depends mostly on hull shape and displacement. Has the designer and builders of the Gozzard had said after trying the boat on both configurations (Full keel and modified fin keel):

"In 1999 we modified the keel again (along with a complete redress of the hull structure). This time we further decreased the wetted surface and used a real 64 Series NACA foil section. The new keel was a little shorter (fore and aft), taller and far more defined. Still too large to be called a fin keel but at the same time it could not really be called a modified full keel either. The results were very positive. The biggest improvement is in performance without any noticeable loss of sea keeping ability. In fact the new design is easier to control, lighter on the helm and obviously faster in all points of sail."

I don't like particularly Ted Brewer as a NA (the designer of Gozzard) that seems quite conservative in its designs not exploring new materials and new technical possibilities nor design improvements. Bob Perry has reached the same conclusion not 15 years ago but 40 years ago when he designed the Vialant:



Regards

Paulo

Last edited by PCP; 04-22-2012 at 11:06 AM.
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