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Full or fin keel?

191K views 846 replies 107 participants last post by  mstern 
#1 ·
Can somebody pro/con a full vs. fin keel for a newbie (will learn to sail on said boat) and taking it thru the Caribbean? All I can seem to come up with so far is fin keel is better to the wind, and a full keel will protect your rudder.
 
#375 · (Edited)
Re: Full or fin keel? Quotes from Robert Perry

Robert Perry's, "Yacht Design According to Perry" (2008, pp. 118-122) has a short chapter, titled "Full Keels" which complements the descriptions above. Expositions are lucid and reader-friendly. And a firm point of view, aligned to an extent with Paulo's, and contradicting some (see points on "stability" and "tracking") -- a position which supports an evolution away from the full/modified-full keel toward at minimum, a hybrid keel, properly and creatively designed and engineered (a provocative topic in itself).

Here are some extracts:

"A full or modified full keel has several disadvantages, one of which is that it lacks the aspect ratio to develop good flow across the chord for lift. In order to achieve an appropriate thickness ratio on a long-chord keel, you have to make it excessively thick, which gives too much added displacement and frontal area. If you reduce the thickness ratio to achieve acceptable displacement and frontal area, the keel may become too thin to keep flow attached and will stall at early angles of attack. Stalling eliminates the keel's lift and causes drag. The good news is that when a full keel stalls and loses life, you're still left with all that planform area to prevent the boat from being shoved sideways. I use a 7 to 9 percent foil thickness ratio for my modified full-keel designs."

"… wetted surface has a severe negative effect on boat speed in light air, therefore an effort should be made to reduce wetted surface. From my perspective though, the biggest disadvantage of a full or modified full keel is the additional displacement it adds to the canoe body compared with a far less bulky keel. On the other hand there are pragmatic benefits … "enough internal volume to house the ballast" "room left over for a tank or two" "contributes to a lower VCG" (most of these boats "use cast iron at 450 lbs/cubic foot (or even less dense materials) rather than cast lead at 700 lbs/cubic foot and in doing so fail to take full advantage of their keel volume to lower the VCG. Lead is always better. It's nice to have a big, long keel on which to rest your boat when you haul out. People also say that a full keel [incl. modified full] protects the rudder, but I wonder. Most full-keel boats still have the heel or gudgeon of the rudder at the lowest point, so there is still a chance of damaging the rudder when you hit bottom. I design the rudder bearing or "Gudgeon" to be at least 4" above the lowest part of the keel to help prevent damage.

I do not regard having the propeller in an aperture [in such keels] to be an advantage … The worst boats to operate in reverse are [such] boats… Of course you may sail in waters littered with lobster and crab pots, or maybe your boat sits on the mud at low tide. A full keel is also a strong shape to have in a catastrophic grounding or if you are pounding on a beach. Haulouts with crude gear may be easier…"

"A sailor must balance these virtues against the full keel's performance vices. To me performance is paramount. This is not to say that all full/modified full keels are slow. Starting with the Tayana 37, I made an effort to separate the full-keel shape as much as possible from the canoe body by reducing the garboard radius and increasing the span. My Taishiba series boats all sail beautifully, and I'm sure that Chuck Paine's similar full-keel boats do also. Look, for example at the new Cabo Rico 45 … [possibly] an example of a modified full keel or the very elusive modified fin keel."

"…given the amount of volume in a full keel, all else being equal, a full-keel boat will be less stable through the normal sailing range, 0 to 30 degrees of heel, than a fin-keel boat. Picture the midsections of a full-keel boat and a fin-keel boat with both boats heeled 20 degrees. The immersed portion of the fin-keel midsection is almost entirely to leeward of the centerline, where it contributes to righting moment via buoyancy. The windward portion of the hull is mostly out of the water, where it, too, contributes to righting moment via gravity. The immersed portion of the full-keel midsection, on the other hand, is still perhaps 40 percent to windward of the centerline, where it contributes to further heeling… technically expressed, the volume of a full keel reduces the righting arm (the distance from the VCG to the transverse center of buoyancy). Thus, not surprisingly, I get a lot of calls from owners of older full-keel boats complaining about lack of stability."

"The stiffest boats are those with deep, high-aspect fin keels with some type of bulb at the tip. It's all about getting the VCG low… On the other hand, it's important to remember that bulbs in themselves are not hydrodynamically desirable. A clean fin has far less drag… A relatively thin, high-aspect fin will have less frontal area than most other keels, which can reduce drag and add up to a downward wind speed advantage, but the thinness comes at a price. [It] poses a structural challenge due to the short chord where the fin attaches to the hull. A short fin makes it difficult or impossible to spread the fin loads over a big section of the hull. You wouldn't want to bounce a fin like that off a reef for a day or two, nor would you want to sit the boat's entire weight upon it when you haul out. Short-chord, high-aspect fins are unsuitable for most cruising boats, which hold durability as a primary desirable feature."

"Remember, more stability means a boat that will stand up to its sail better and present a more efficient keel shape to the water. People like stiff boats… It's often argued that a full- or modified full-keel boat has better directional stability, which is often referred to as "tracking ability." My experience is just the opposite. I have found that the further I can separate the keel form the rudder, the better a boat tracks… I'm a believer in the 'feathers on the end of an arrow' theory. In other words, keep the rudder as far aft as possible."

"… [L]imiting yourself to more 'normal' cruising keels, you arrive at hybrid keels like those in the accompanying illustration. This is an external keel for the 57-foot cruising sled 'Mobisle.'… I have used this hybrid keel shape on three of my 'cruising sleds.'… Obviously you want to limit draft on any cruising boat, and this severely ties the hands of the designer."
 
#376 · (Edited)
Re: Full or fin keel? Quotes from Robert Perry

Thanks for posting. Interesting and informative read.

Robert Perry's, "Yacht Design According to Perry" (2008, pp. 118-122) has a short chapter, titled "Full Keels" which complements the descriptions above. .. a position which supports an evolution away from the full/modified-full keel toward at minimum, a hybrid keel, properly and creatively designed and engineered (a provocative topic in itself).

Here are some extracts:

"…given the amount of volume in a full keel, all else being equal, a full-keel boat will be less stable through the normal sailing range, 0 to 30 degrees of heel, than a fin-keel boat. Picture the midsections of a full-keel boat and a fin-keel boat with both boats heeled 20 degrees. The immersed portion of the fin-keel midsection is almost entirely to leeward of the centerline, where it contributes to righting moment via buoyancy. The windward portion of the hull is mostly out of the water, where it, too, contributes to righting moment via gravity. The immersed portion of the full-keel midsection, on the other hand, is still perhaps 40 percent to windward of the centerline, where it contributes to further heeling… technically expressed, the volume of a full keel reduces the righting arm (the distance from the VCG to the transverse center of buoyancy). Thus, not surprisingly, I get a lot of calls from owners of older full-keel boats complaining about lack of stability."

"The stiffest boats are those with deep, high-aspect fin keels with some type of bulb at the tip. It's all about getting the VCG low… On the other hand, it's important to remember that bulbs in themselves are not hydrodynamically desirable. A clean fin has far less drag… A relatively thin, high-aspect fin will have less frontal area than most other keels, which can reduce drag and add up to a downward wind speed advantage, but the thinness comes at a price. [It] poses a structural challenge due to the short chord where the fin attaches to the hull. A short fin makes it difficult or impossible to spread the fin loads over a big section of the hull. You wouldn't want to bounce a fin like that off a reef for a day or two, nor would you want to sit the boat's entire weight upon it when you haul out. Short-chord, high-aspect fins are unsuitable for most cruising boats, which hold durability as a primary desirable feature."

"Remember, more stability means a boat that will stand up to its sail better and present a more efficient keel shape to the water. People like stiff boats… It's often argued that a full- or modified full-keel boat has better directional stability, which is often referred to as "tracking ability." My experience is just the opposite. I have found that the further I can separate the keel form the rudder, the better a boat tracks… I'm a believer in the 'feathers on the end of an arrow' theory. In other words, keep the rudder as far aft as possible."
Regarding this:

"The stiffest boats are those with deep, high-aspect fin keels with some type of bulb at the tip. It's all about getting the VCG low… On the other hand, it's important to remember that bulbs in themselves are not hydrodynamically desirable. A clean fin has far less drag… A relatively thin, high-aspect fin will have less frontal area than most other keels, which can reduce drag and add up to a downward wind speed advantage, but the thinness comes at a price. [It] poses a structural challenge due to the short chord where the fin attaches to the hull. A short fin makes it difficult or impossible to spread the fin loads over a big section of the hull. You wouldn't want to bounce a fin like that off a reef for a day or two, nor would you want to sit the boat's entire weight upon it when you haul out. Short-chord, high-aspect fins are unsuitable for most cruising boats, which hold durability as a primary desirable feature."

Bob Perry, even if he considers very short fins (I call them foil bulbed keels) advantageous in what regards sailing qualities, sees them unfit for cruising boats, based on lack of durability and structural difficulties. Nevertheless they are incresingly used in fast cruising boats.

I agree with what Bob says about the structural challenge to be bigger however many boat builders resolved that with an elegant structural solution: A carbon or steel large frame where the keel is attached and that receives also the loads from the stays. This way all the keel loads are distributed by the hull and the attachment point is incredibly strong. The keel construction has also to be different from the more traditional ones to give more resistance to that thin foil. Several methods are used being the most strong a machined piece of solid steel where the lead bulb is attached.

Of course this has a disadvantage: price but an increasingly number of manufacturers are using the system among them: Salona, Comar (Comet), Grand Soleil, X-Yachts, Luffe, Arcona.

Regards

Paulo
 
#377 · (Edited)
There are certain basic atributes that apply to all full keels and others that apply to all fins (as I have mentioned earlier) each have advantages and disadvantages....but taking the best attributes of the best designed fins and comparing them aganst the worst of the full (which appears to be happening cumulatively) just isn't fair and/or defeats the purpose ofthe thread. A well designed full has these same advantages in performance over a poorly designed fin while keeping the traditional advantages of the full (in all fairness I will point out this works both ways). I pursonally prefer a well designed full...that said in a honesty there a a few fins I would be happy with.
 
#379 ·
I think by asking this question,first you have to ask yourself what type of sailing you are going to do.If you want to cross oceans and want a proven multi functional design chose full keel.
If you are going to hang around the coast chose fin keel
 
#380 · (Edited)
I am now just really realizing that I no longer have a boat good for gunkholing :(. (full-keel Morgan Columbia 40)....could be worse though since she drafts only 4 and a half...

.....but for island-hopping...say... thru the Bahamas and the "thorny" on down which I hope to do someday soon...I am glad to have a train-tracking, full-keeler that can hold a course on a 1-2 or 3 day leg without always having auto-helm turned on...but instead just lashing off the wheel...and I can possibly take 15 minute nap,if single-handed (with multiple set alarms) and hold a course too without autohelm..I have never had an auto-helm/auto-pilot on any of my former boats...so this is new ....and am not familiar with auto-pilots yet...but for now...gimme a full-keeler..or cutaway-forefoot...One day when I'm older ;) and can afford a marina and need maneuverability...I'm sure I might spring for .5 kt faster fin-keeler
 
#382 ·
50 years ago virtually everybody sailed a full keel boat - whether daysailing, coastal cruising, or crossing an ocean. They raced them as well.

The last decades have seen many changes to design, some from racing rule influence, some from design knowledge.

Today more boats with fin keel and aft rudders, either on a skeg or a spade, are crossing oceans than full keel boats.

As the keels were shortened to reduce wetted surface the forefoot was cut back and the rudder moved forwards, ending up close to mudships in some boats. This doesn't make for a very efficient rudder and added to its location it was usually raked forward at a steep angle.

The aft rudder was the solution. Leaving the keel to be designed as an efficient foil.

I agree with Paulo and the Maestro - the feathers should be on the end of the arrow.

And as with everything there are both good and not so good designs of either type.
 
#383 ·
This discussion could be tightened up a bit, I think, if we could get away from vague terms like "Full" vs. "Fin" and focus on the relevant parameter: aspect ratio. This is basically depth divided by chord (length in the direction of water flow) A more formal definition involves area but is just a refinement.

A "Full keel" boat has a low aspect ratio underwater profile, maybe 0.5 depth to chord, and a "Fin keel" boat has an underwater aspect ratio of at least 1:1, and as high as perhaps 7:1 in the various Open class racers.

The sail plans usually follow these trends, low aspect ratio (think CCA or "America") on full keel hulls and tall rigs on the more racy vessels.

If you look at the L/D curves in C A Marchaj's Theory and Practice of Sailing (best book ever, on the subject, IMHO) you see that there is no question that the high aspect ratio system is best in terms of absolute performance, i.e. getting to windward. (I won' t get into going downwind as damn near anything can do that.)

The L/D ratios at optimal angles of attack are very high for high aspect ratio foils, whether air or hydro, and correspondingly lower for low aspect ratios. This is just simple physics -- the end, which is a leak, is smaller and farther away.

The thing which is important as to this discussion, i.e.which is preferrable, is to be found in examining how the L/D ratio varies with angle of attack. Keep in mind that angle of attack is the angle between the apparant wind vector and the span of the foil. It is determined, hopefully, by how you steer, but also by wind shifts, pitching, rolling, yawing of the vessel, elsticity in the rig and on and on.

The L/D plots for high aspect ratio systems have very high peaks BUT this high performance peak occurs over a very narrow range of angles of attack.

The same plot for a low aspect ratio system shows a broader range where the L/D is not as high as before, but does not change so severely.

So, what's best?

If you love clawing to windward and ekeing out a 1/32 point advantage over a competitor and are willing to stand white-knuckled at the helm to do it then the high aspect ratio, i.e."fin-keel" is the way to go. But bear in mind that if you get out of the groove with either the sail plan or the detached spade rudder, either or both will fall off of that peak in the L/D curve, i.e "stall" and you may well end up ass-over-teakettle with your boat wondering what the hell you were trying to do.

If you'd rather let the boat sail herself for the most part, the broader range of the low aspect ratio is more appropriate. The extreme of this is the old Tahiti ketch with the helm lashed and the skipper sipping rum all the way across the Pacific.

Having said that, there are qualifications:

There are some very nice designs out there which offer a sensible compromise -- but they are all pretty old and therefore not very fashionable. To my mind the epitome of yacht designs of this sort was in the postwar years but before the CCA and subsequent rules began to seriously deform common sense. These boats had tall, but not preposterous rigs, deep but not overly long "full" keels, strongly cut away in the forefoot and after body (aspect ratios around 1:1, thus somewhere in the middle of the current arguement) but blended structurally, and hydrodynamically -- look at the bottom of a C Morgan boat to see what I mean -- also perhaps a bit structurally sounder than the more recent bolt on fins.

I think the unfortunate trend in modern yacht design is that the buying public seems easily beguiled into thinking that the design principles of a Volvo 60, manned by a bunch of professional athletes standing watch on watch and probably terrified nearly every second (but loving it, I am sure) is somehow the right thing for the average guy and his mate, or vice versa, who want to go to sea.

I kind of don't think it is and will offer two observations to support this:

1. Most of these wide beamed, high aspect ratio fin-keeled (with spade rudders) and similar tall thin rigs spend their time as patios.

2. When you do see them sailing they usually do so with an enormous amount of twist in the sail rig -- Harken even advertises windward sheeting mains'l travellers to promote this -- so as to lessen the "twitchiness" of the high aspect rig referred to earlier. With a twisted foil, there is always at least some part of it working properly -- but never all of it. If they could figure out how to make twisty fin keels and twisty spade rudders we'd see fewer "crash jibes," "death broaches" and all the other terms recently invented to describe the behaviour of these things.

Paolo and/or Polux opines that the NAs design and the builders build these sort of vessels because that is what the buying public wants. I suspect that he is right but that the buying public is, as usual, seriously stupid, at least in the short term -- did we really need tail fins on our cars in the 70's?

And I remember a recent (year or so ago -- that's recent to me) in Cruising World where all the Senior Editors chose their own ideal cruising boat. There was not a single modern design in the lot. They were mostly of the type I described above or perhaps a bit later when the "Brewer Bite" became fashionable. None of the types heavily advertised and reviewed in the same pages, ironically.

In the end -- to each his own -- but do some research and have a bit of a clue as to what to expect from the physics of the various design parameters.
 
#384 · (Edited)
....
I think the unfortunate trend in modern yacht design is that the buying public seems easily beguiled into thinking that the design principles of a Volvo 60, manned by a bunch of professional athletes standing watch on watch and probably terrified nearly every second (but loving it, I am sure) is somehow the right thing for the average guy and his mate, or vice versa, who want to go to sea.

I kind of don't think it is and will offer two observations to support this:

1. Most of these wide beamed, high aspect ratio fin-keeled (with spade rudders) and similar tall thin rigs spend their time as patios.

2. When you do see them sailing they usually do so with an enormous amount of twist in the sail rig -- Harken even advertises windward sheeting mains'l travellers to promote this -- so as to lessen the "twitchiness" of the high aspect rig referred to earlier. With a twisted foil, there is always at least some part of it working properly -- but never all of it. If they could figure out how to make twisty fin keels and twisty spade rudders we'd see fewer "crash jibes," "death broaches" and all the other terms recently invented to describe the behaviour of these things.

....
The one that know me know that I am a firm believer that each sailor should have a boat adapted to his sailing tastes and not otherwise. The big choice in the boat market, specially on the European one is a clear sign that choice exists. Boatbuilders that make boats that no one wants go bankrupt and out of the market. It is as simple as that.

This thread is not about choice of sailing style but about the means to provide that sailing style. What I have been saying is that even for the ones that like heavy boats (and that are some still made today) a fin keel or a modified fin keel on those boats makes everything a full keel would do, only better.

This is not about the choice of the type of boats (performance cruiser, voyage offshore boat, coastal cruiser, heavy, medium or light sailboat or the type of sailing each one prefers, this is about sail design: the best solutions to attain a mean that is, a given type of sailboat.

Regarding what you say concerning the difficulty of sailing fast performance boats directly derived from racing boats, it seems to me that you are the one that is partial. I do understand and see as natural that others have different sailing options regarding the ones I prefer. It is you that think that for offshore work all the boats should be like the ones you prefer for that kind of sailing.

Just to show how wrong you are about sailing difficulty I will post here what Eric, the happy owner of a brand new Pogo 12.50 (the cruising version of a racing 40class boat), said about its first sail on its boat (I hope he doesn't mind).

…..

Last week we sailed the boat over to Nieuwpoort, which was a cold but nice and very valuable experience. I will be happy to discuss this in more detail later, but the bottom line is: the boat dislikes pointing or sailing dead downwind, keeping up the speed is the issue and then the VMG is always very correct. It is quite a different way of sailing compared to more traditional designs.

I mentioned before the statement of an experienced class 40 sailor: it's just like a big 470 dinghy. I've been sailing a 470 for almost 30 years and could not agree more. "Sail the boat under the mast" and first try to build up the apparent wind. Then you get exhilarating sailing everywhere between a close and a broad reach.….

The initial (form) stability is as spectacular as the 4m50 wide (and honestly quite disgraceful) beam. Even with myself and my two basketball centre players of sons on the same side, the boat hardly moves.

Under sail, more than 20° of heel only slows the boat down. But before you get there, you have already enjoyed the enormous power of both the hull (form stability) and the 3m deep, leaded keel (weight stability).

Between l'Aber Wrach (North Brittany) and Cowes we kept all the sail (full main + solent) up in 25 knts on a broad reach. With nice, long, 3m high waves and gusts up to 35 knts the average speed was around 14 knts with some wonderful long and thrilling surfs up to 21 knts, without ever feeling out of control.

So our first experience after 450 NM with the 12.50 is: WYSIWYG.

A big 470 with visually basic, but functional and in fact quite comfortable accommodation for our crew of 6.

Eric
To make things clear that boat option is not the one I favor to myself, not because it is too radical in what regards sailing but because it has an interior "too clean" for me and because on the type of sailing I do I make a lot of upwind sailing that is not the strong point of that boat. But if I was circumnavigating, following the trade winds you can bet that it would be that the type of boat I would chose…and I am not implying that would be the right choice for you or any other that prefer slower heavy boats with a different sea motion.

Regards

Paulo
 
#385 ·
Paulo:

Thanks for the response. But your statement, "It is you that think that for offshore work all the boats should be like the ones you prefer for that kind of sailing," is off the mark. I never try to tell anyone what they should do. Gave that up long ago. I was pointing out the physics implications of the various design choices.

The post by EricKLYC is interesting. I would note the following:

"... but the bottom line is: the boat dislikes pointing or sailing dead downind."

"... it’s just like a big 470 dinghy."

"... on a broad reach... without ever feeling out of control." Well, I should hope so, given that on this point of sail most would be taking a nap.

This all just confirms my points that these things are "big dinghys."

I would also observe that almost anyone who goes for a first sail in a brand new boat is ENTHRALLED.

What I think this discussion needs, and what I tried to provide, is some guidance to the prospective buyer as to what sort of behaviour he or she might expect from a boat by considering some quantifiable and specific parameters of it's design, namely the aspect ratios of its underwater form and sailplan. There are many other design parameters as well, of course, but they are off topic.

What you or I or anyone else prefers is irrelevant. The point is to understand how a boat is likely to behave given these measureable parameters, and whether that is what the prospective thinks he or she might want.

You seem to want to deal in vagueries, opinions and personal attacks. I have little patience for any of that.
 
#387 ·
..

"... but the bottom line is: the boat dislikes pointing or sailing dead downind."

"... it's just like a big 470 dinghy."

"... on a broad reach... without ever feeling out of control." Well, I should hope so, given that on this point of sail most would be taking a nap.

This all just confirms my points that these things are "big dinghys."
You seem to forget some relevant facts and it is not hard to understand why:D

Regarding this:

"... on a broad reach... without ever feeling out of control." Well, I should hope so, given that on this point of sail most would be taking a nap.

You seem to forget that the boat was sailing with full sail, 25K wind, gusting 35K, with 10ft waves, averaging 14K with points at 21K. I find amazing that a cruising sailboat can do that without the skipper felling the slightest loss of control, even more so on the first sail on an unknown boat.

Regarding this:

"This all just confirms my points that these things are "big dinghys" you are wrong about that. What Eric is saying is that the boat SAILS like a big dinghy not that is a big dinghy. He knows and I know that his boat has an outstanding final stability with a great AVS. A dinghy has not that and relies on the weight of the sailor not to capsize and when capsized at 90º it will not re-right itself without the help of the sailor's weight. It is not a big dinghy, IT SAILS LIKE A BIG DINGHY.

Regarding this:

"... but the bottom line is: the boat dislikes pointing or sailing dead downind."

You seem to forget what he wanted to say, or maybe you did not understood. He said:

"the boat dislikes pointing or sailing dead downwind, keeping up the speed is the issue and then the VMG is always very correct. It is quite a different way of sailing compared to more traditional designs".

He knows and I know that his boat is faster against the wind, VMG, than most modern performance cruisers, not to mention any heavy old keeler. What he is saying is that the way to sail the boat against the wind is different: the boat goes faster (VMG) if a bit out of the wind (compared with another performance boat, maybe at the same angle as a full keel boat) because it makes much more speed that way and in the end the VMG is better.

The same happens dead downwind and not only with this boat. With any modern performance boat is the same in what regards sailing downwind and regarding VMG and they are faster that way VMG than any older boat.

Regards

Paulo
 
#388 · (Edited)
There's alot of folks in here who are interested in planes also I have noticed so as a one time pilot in my late teens and albeit I had only three solos in small cessnas...this discussion of different boats make me think of different sorts of aircraft....seems that this is like comparing say a Cessna 172 vs. an aerobatic plane...The Cessna 172 is generally alot slower but stable over a wider envelope of conditions...big drag- producing but stable vertical stabilizer(tail) and again a thick drag-producing wing that inhibits speed but allows high lift and high stall speeds...and good stability before it loses that lift in only highly unstable (low-speed or due to high pitch,angle of attack with correlating loss of lift, type conditions.
The aerobatic sport plane like a Pitts with thin short wings can go a hell lot faster..but the pilot has to be on top of things because of the built-in instability stemming from the thinner less-lift producing wings...greater speed of landings (stall speeds),etc...turbulence will also likeley affect the aerobatic plane more...as well as having smaller cargo capacity,fuel capacity,etc...Meanwhile the Cessna will carry four and alot of gear a fairly long way but at much slower speed..You pick...depending on what you want out of your (plane)boat...In this case obviously, the Cessna is the light cruiser and the Pitts is the "racer"...
 
#397 · (Edited)
Thought it looked very familiar of late...there's been alot of discussion of valiant 40's lately...They have alot going for them certainly. I think that photo may have even been posted on another thread recently...I guess it is not that tubby really...especially compared to catalina 400 or Morgan OI's...
My old Morgan Columbia 40 is 10' 6" on the beam...39' and change loa...She comes in a bit over 7 knots theoretical..The bow itself may not have wave-piercing slender-entry...but being narrow...the whole boat does have wave-piercing form...also gives back some maneuverabilty lost by the full keel too...She has lots of storage and tankage... some reserve bouyancy with her overhangs...etc Agreed, they all have their plus and minus...one just has to find the boat that's right for you.....
I have felt lucky to get every boat I have had...And often just as happy to see 'em go...I said goodbye to my S&S Columbia 29 with some regret..but I'm over it..same thing with the Seafarer24..a fine daysailer and capable of occasional and select coastal work...Some day I'll want one of those back perhaps...I get old boats on the cheap...as long as they got some sailing left in them...I sail 'em as much as I can and then sell them for more or less what I got 'em for when something better comes along...I don't think there's much new under the sun , newer sailboats are still slow. Just often less comfortably so... IMHO. Now I got a boat I'd like to keep for awhile I think...that the guy in the 40-foot trawler is going to have a harder time sloshing me about in on the weekends...and while not discussed often...that kind of "performance" counts for alot in busy SW Florida channels...
 
#398 ·
Yes beam has increased a lot in the last few decades. I think the Valiant is a great design, not super light but not massively heavy either, and a good performing boat in most if not all conditions. A Valiant 40 won its class in the Swiftsure race out of Victoria last year.

Even though it would be fun to sail a Pogo or one similar they wouldn't be my choice for an offshore boat.
If I could have my ideal boat built it would be moderate displacement, virtually no overhang, narrow with balanced waterlines, fin keel with spade rudder right aft, interior similar to a 35' boat - but about 45' long. A smaller Sundeer.
 
#403 ·
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 :)
 
#404 ·
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.
 
#406 · (Edited)
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.
.
 
#408 ·
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
 
#407 · (Edited)
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.

Dave
 
#452 ·
Dave, evolution does not always mean "better". Things "evolve" for different reasons...in the case of a sailboat, evolution might mean that boats become cheaper, appear flashier, have a shinier finish and require a blazer to sail.(sorry but cant help but put in the picture of the beneteau the arch in here)



Also as others have pointed out, there were fin keeled boats 100 years ago, it has nothing to do with the technology not being available.

As far as your paragraph

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.
I'm trying to imagine a catalina 30 out here off the Oregon coast compared to my Westsail 32 and coming to the conclusion that what you say is completely wrong. The person in the Catalina 30 is going to have to have far better sailing skills than the person in the heavier older design. That light fin keel boat will require much more attention to keep out of trouble.
 
#409 ·
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.
 
#410 · (Edited)
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.
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.

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
 
#411 · (Edited)
PCP :

Why on earth would "lighter on the helm" attract anyone on a long haul?

I remember 27 days with a long keel and heavy helm.

I would not trade it for anything.

But then again, maybe if I had a lighter helm my boat would have been more fun, or "sail better" or something?

Try a long haul sometime on that Benetau. Steer it manually too. Then try a long keeler with a heavy helm. It'll be educational. But don't compare the two ships around the marks on a day race, or you will find that you will like your Benetau so much that you will never touch a long keeler ever again.

Better still, take your Benetau out into a mid Atlantic gale, wait for the rollers to build, and run before them off the quarter. When you do, you may find helm sensitivity is not one of your priorities. Nor speed.

I have done a long haul with a long keeled ship. By contrast, a single afternoon with a deep fin convinced me it was not for me. It was fun, but I wouldn't want to own it. That decision was nothing to do with the age of the ships, or materials, or computers.

No. Deep fins are simply not for me.

I don't like them.

Give a ship like this a fair trial...

http://sailboatdata.com/viewrecord.asp?class_id=3306

.... in the rough stuff, running before a big sea.

You may get to like that keel more than you think.
 
#412 ·
PCP :

Why on earth would "lighter on the helm" attract anyone on a long haul?

I remember 27 days with a long keel and heavy helm.

...
An heavy helm does only mean that the boat is not well balanced. Some full keel boats have an heavy helm even with a rightly balanced sails.

A boat with a light helm does not mean that it has an inferior tracking ability or that it stays less on its course, just that you need to make less force to maintain or alter course and therefore will require less energy from the autopilot.

If you have the sails balanced (as any good sailor would have) on a well designed boat, as most on these days, you can let go the wheel and the boat will continue happily its course.

Regards

Paulo
 
#413 · (Edited)
I want to do a yawl-conversion on my 18,200 lb Columbia 40 full-keeler...gonna be awhile though...need to address the steel skeleton though should just be preventative...like drenching it with rust-inhibitor...will eliminate it altogether down the road..and then the hydraulic-armed centerboard...same thing for now...rust-inhibitor...then I don't know until further examination of the components... but need to fix and re-enforce the foredeck first actually...got a sweet drop-forged 6"x6" base ss sampson post from old-school days I am gonna put there...yawl-conversion eventually as I said is a possibilty,,and might not be too much more costly than a self-steering system or a new but usually questionable autopilot...I know that being narrow at 10' 6" the boat will be a failry wet ride at hull speed(7.16 kts) but she should be fairly stable surfing and she can punch through oncoming chop I am sure...and the thing is like the rock of gibraltar at anchor in 20 mph winds...sippin rum...wish I was on her now...I love her...Yes..am still in honeymoon stage...don't ruin it...fin-keelers are fine...whatever..:rolleyes: Just happy with what I got...and that is.... a boat I feel can go alot of places...
 
#414 ·
PCP :

By "lighter on the helm", they mean that it needs less input at the helm to change course. They are not talking about sail balance.

I would be very interested to see that Benetau of yours hold its course on a broad reach.

Hands off with no autopilot?

My long keeler won't.

That Benetau must be quite a ship to hold a broad reach hands-off.
 
#416 ·
As far as manuvering in tight spaces I find heavy displacement has it's advantages. Put it in reverse and throw the helm over one way and just as you are starting to move backwards, put it in forward and throw the helm over the other way, this allows you to turn the boat on it's own axis...I have even seen it done with a 100' schooner (and no bow thruster).
 
#418 ·
If you are planning on SW Florida and key and Bahamas, you need a shallow draft boat. Period. DOn't listen to these guys with 7-9 foot drafts in the NE or PNW. I have about 5'10 (6 foot after all the pots and pans) and I run aground ALL THE TIME!! And I know the area very well.

You are starting in FMB. Unless you don't mind sitting a lot and waiting for a tide or running aground in the miserable mile, go shallow draft. Six foot max. THis is typically a wing keel. SOme modified fulls will work too.

As far as the the theoretical debate about which is better, for racing and deep water, I would always go fin. But for cruising anywhere that has shallow water, 6+ is tough, and anything at 7 for much of the area I have been is a waste of time. That has been my experience. I personally would never own a deep draft boat which rules out most fins for me. I don't like 6'!

I know the area you are in. Trust me. I have seen 3' draft motor boats run aground all the time.

Brian
 
#420 ·
boy Brian, if you run aground a lot down there with NO tide change, I do nto want to know how you would do up here in the northern climes with 12-15+ foot tide changes. I see 7.x-22.x' at my slip on extreme tide change days on the depth guage!

at the end of the day, one needs a keel that works for them, hull shape that works for them, hull strength for conditions they will meet etc. Not sure a hershoff(sp) 12.5 will make a good ocean going rig in many conditions, even tho designed by a known great architect, full keel etc. that open cockpit will probably kill it! if the light scantlings do not in the mean time.

Marty
 
#438 ·
Hey Marty,

The difference is that (for example) Dad has 22 feet under his keel at low tide. I generally have about six inches. We measure our water depth in inches under the keel down here! I generally anchor in about 7-10 feet of water. You have to get many miles offshore to even hit 20 feet of water! Anything over 6 and you simply will be very restricted on where you can go down here. I say, pick the keel for where you plan to cruise or how you intend to use the boat. In some areas, draft makes no difference. In some areas, it does.

BTW, hopefully we can meet up one of these days. Beautiful area.

Brian
 
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