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Paulo , forgot to mention, I said this before, but I sail my own boat
at 15 to 17 degrees heel too. I can do it with whatever sail I choose to keep the boat at that heel. I get within 2/10 of my target speeds.
Point being? yes , your manufacturer is actually telling you that is the ONLY range the boat is food for .... yes, another compromise. and I am sure the list goes on...

No one forces you to sail at 30 degrees heel. I agree if your boat is not easily driven , you may be forced toward that end of the envelope. But to actually have to do it is typically unnecessary and certainly not comfortable.

You may ask however , how one of these boats you want so much would behave if you were forced to sail at 30 degrees. You may find them unmanageable. Something I don't have to be concerned with not having a wide transom. Did you say that could be handled with twin rudders? (chuckle)
 

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Jeff, in reading Paulo's reprint you state that I "obviously" have not sailed a boat similar to yours.
Please tell me which boats of these (35-40 ft range) are closest to yours I have also raced hot dogs mostly, offshore on a couple too

J35, Express 37, C&C 37R, Schock 40 TFCC, Farr 40, Santana 35, Creekmore 33 I think, J40 (too heavy) Farr 36 one ton 1980? , J-105

Having sailed and raced these, tell me if you think I am qualified to forward
any findings of facts?
(chuckle)


None of these are particularly similar to my boat. The J-35, and J-40 are derived from 1970's era MORC thinking adapted to larger boats. They have much flatter bottoms, with their center of buoyancy further forward fuller bows and the more pinched transoms that was typcial of boats of that era and genre. The J 105 is only slightly improved next generation thinking and optimized as one-design race boats.

The Santana 35, Creekmore 33, Farr 36 One Ton, and C&C 37R are all IOR derived designs with very different hull forms and comparatively miserable motions. The Farr 40 is probably closest, but these were built as full blown, grand prix level, one-design race boats with their designs evolved from IMS thinking of their day. In terms of speed, as well as overall hull and rig design, they are very advanced designs compared to my boat, but my boat was designed primarily as a performance cruising boat, they were solely designed to be raced.

Probably the closest of the designs on your list is the Express 37. This is one of my favorite boats from that era, and one which is faster than my own boat on almost all points of sail. But I did not choose to buy an Express 37 partially because it was more optimized for reaching and running, and racing. They also have less tankage. With regards to this dialogue, as much as I liked the Express 37, I was concerned that the Express 37's fuller bow sections gave it a less comfortable motion in a short chop (especially beating) than the boat I chose to buy, which has a very different rig and a very different hull form with a finer bow, higher ballast ratio, and its center of buoyancy moved further aft.

If I could afford to build a custom 38 foot design today, I would probably want less wetted surface, a slightly narrower beam at the deck line, more eliptical hull sections, a slighly narrower stern, a bulb keel, a larger fraction rig, a little more freeboard, a slightly lower house, better ventilation, a little larger fuel capacity (although I typically use about a tankful of fuel per year which is probably a good thing), a dedicated shower, maybe an aft stateroom instead of the double quarter berth. But then again for what I do and where I sail, the boat works great for me.

Jeff
 

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I also have a beef with statements about having great advancements after IOR , I say hogwash. Static curves for one got worse
kev
Some knowledgeable information on IOR sailboats:

"Often accused of prohibiting great boats by encouraging mediocrity, the IOR …boats did not offer exciting performance off the wind, which was another reason for evolution away from the IOR.

..Peculiarities of IOR designs result from features that increase actual performance more than they increase IOR length, or other odd rules; IOR hulls bulge at girth measurement points; a reverse transom moves a girth measurement point to a thicker part of the hull; waterline length is measured while floating upright, so large overhangs are used to increase waterline sailing at speed; the stability factor ignores crew, so IOR designers assume lots of live ballast.

… The IOR encourages high freeboard and high booms and prohibits keels wider at the bottom than at the top (bulbs). The IOR, in sum, encouraged heavy boats that lacked fair lines and clean hull forms.

…..…. The IMS took the actual hull lines and analyzed their continuum, essentially eliminating funny bumps or hollows in the ensuing yachts and generally rendering much cleaner, faster lines that were far more exciting, safer to sail, ... "

International Offshore Rule - Wikipedia, the free encyclopedia

"While there is justifiable nostalgia today for the old IOR level rating of the IOR 1/4 ton. 1/2 ton and 1 ton class, change was necessary, as the IOR could and did result in some unseaworthy boats being designed and built."

Sailboat Handicap Rating Systems

Regards

Paulo
 

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paulo , you are referring to the end of the IOR not the early seventies
But aside from that boats designed after that had worse curves.
like LPS of 105 deg.. laughable . Now stop with the disinformation. You are a hopeless romantic.


Jeff, You certainly study this, however I don’t believe
These subtle differences provide more than slight performance
advantages and all of them have their own set of compromises.

You and some others slam the comfort formula but what gets me is you (they) don’t forward a definition of comfort. So therefore , until a definition is established, you have no right to criticize some ones work . My stand is comfort says that when weight and moment of inertia both in pitch and roll is decreased, higher accelerations are generated and that is not comfortable.

I have listed a Farr 40 and a J40 , now there is a huge difference, the J-40 being noticeably more comfortable, however on a J-35 or an express 37, I would bet If you blind folded me and sailed me around I would have some difficulty knowing which boat I was on. In that performance bracket I may be able to detect the C&C ,which is actually 39 feet I believe, but I would not put money on that either. I do remember the cockpit of all those boats are uncomfortable and unacceptable for my standards.

Since the 70’s There are only two big design changes in these newer boats. The most popular boat which launched the new design trend was the J-35, and that trend is weight reductions and wider transoms, makes for faster off wind speed. That design trend was nothing new , it was no breakthrough development. All it amounted to was extending dinghy design into bigger boat design. No different than Mark Soverel extending surfboard lines into sailboat hulls , just big dinghys like a 60 year old Flying Dutchman …..
. Racing here and everywhere is downwind . No one except myself and some other lone wolves where ever they exist want to race up wind.

As for comfort, meaning to me, among a few other things is being able to cut a wave in half without bracing myself ; big and heavy wins. If you like to shoot through or over the top of a wave fine, but if you call that comfortable, then you will have to redefine what comfort actually is. Comfort is low accelerations in my book and that is also the criteria for the
Comfort index formula we are arguing. The math in the comfort index supports low accelerations and also statistical data of wave mass vs: boat mass.

I will close with saying I have sailed 50 or so boats up to the C&C 61 Sorcery by far the most comfortable , My Ericson 46 rating second, and more comfortable than a Swan 46 because I don’t pound, same for Baltic 48 and way more comfortable than a SC 50. I won’t tolerate pounding. These boats today have no forefoot They track miserably , and wear out autopilots, pound pound pound

One thing I don’t do is confuse comfort with excitement, like you Paulo
A last note , cruisers spend a lot of time on anchor. That’s important too.
Paulo, you are dreaming if you think those boats are quiet below.
You can pull the sales job on your wife all night, and in the end when she forgives you, You can at least name the boat “Love is blind”

I say your comfort argument It is a joke, just brainwashing yourself magnifying tiny variations into a feel good.

Mass and moment wins hands down , the formula is good

Now i am off for 4 days to split some waves in two, You guys can carry on
in bliss.

Oh Paulo , how are you doing with the curves ??

I have a few more names by the way :

Fanny Slapper, Black and Blew, knuckle pounder, Midnight serenader

Now jeff, don't get in a puff, Paulo and you are all big guys now.
 

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BTW Paulo

The J-35 needs all 1650 lbs crew allowance to make it's numbers
so much for your IOR data.
The newest boats today need rail meat, they do nothing but sit and switch sides. THE SC 50 needs 12 on the rail
Who are you kidding ??

The pot should not call the kettle black
 

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Back in Post 73 I proposed a definition of a boat that offered desireable moion comfort. I suggested that a boat design that had desirable motion comfort characteristics would be a boat met some basic criteria in terms of balancing the shape of the boat (bouyancy distribution) and the weight distrubution within the boat so that the boat minimized both the amount of motion and the acceleration/ decceleration felt by the crew.

And we agreed in principal that the amount and rate of change in speed of motion that a boat experiences is related to the amount of energy that is imparted into the boat, the ability of the boat to store that energy, and the ability of the boat to dampen (disburse) that stored energy. A design that offered comfortable motion would be one that attempted to moderate these sometimes contradictory factors.
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Yes Jeff remember your post, and I agree in the details you have
enough variables to play with and agree with your approach and
that your concepts are in the right direction I also see you are not just going to buy into anything that is not vigorously challenged and analyzed.

however, I would pose the question of
how this optimization, which I would refer to as 2nd and 3rd order effects,
weight and moment being the first order effect,, anyway I would ask
how far the 2nd and 3rd order effects get buried in the randomness
of a developed sea.

Could you actually detect these more subtle design changes out there?
What may be clearly detectable on smoother water with lets say a
steady chop, both direction and amplitude. This is just a thought.

Don't get me wrong, I believe designs can be optimized for particular venue
and purpose, and so I say new "designs" are evolved for down wind speed.
That sells.

In your boat upgraded design which you propose, I don't think you have
anything in mind other than performance to satisfy your own requirements.
So you are not designing it for some profit volume incentive and therefore compromise to that end. example of that approach would be Bose speakers.



I can give an example of my venue application here.

We sail out of LA Harbor to Catalina Island regularly with our club members
and land a few miles to the west of the Isthmus , so it is an upwind climb
and if you get off the dock after 12 noon, you are in for a rough ride.
Making it on one tack you will be going up in six foot, some 7 foot breaking
and now and then a set of 8's. This is hard on the wind with the skirt inside
if you can do it. This goes on for a good 3 hours. Summertime afternoon winds develop a short wavelength rugged chop with breaking tops.

The option is to this is leave earlier and motor in no wind, maybe get an hour of sailing in. or crack off put in a few hitches, and get there at dark

To give an example , on my 41, all my sheet lines hung up in the forepeak
with clove hitches ended up in a heap on the sole. Even I was pounding on the big ones.
and my foredeck soaking wet. But in the end it was still fun, and in the cockpit , we were quite dry and having fun. We also have the gloating feeling that when we take a mooring can, we did this in one tack, most boats won't or just can't. We keep our gloating to ourselves however.

Anyway, this is the type of sailing I expect a boat can do and still be balanced and not get beat up.
OK now I have to go, cheers
 

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paulo , you are referring to the end of the IOR not the early seventies
But aside from that boats designed after that had worse curves.
like LPS of 105 deg.. laughable . Now stop with the disinformation. You are a hopeless romantic.
....
You say seventies? Boats in these days were not changed every two year's. Most of them were raced for many years. Many boats from the early 70's and mid 70's were racing on the 1979 Fastnet.

Take a look at what they say about IOR boats of that time and also to the large improvements that the IMS brought (over IOR) to the design of better and safer sailing boats.

Jeff as been saying that, I am saying the same, it looks everybody agrees on this...except you.:)

"In the infamous 1979 Fastnet race, 5 boats sank, 24 boats were abandoned, and 15 lives were lost. This tragic loss was largely attributed to the "tortured" hull forms that had arisen out of designers' attempts to manipulate key IOR measurement points and to the relatively low ultimate stability of the latter generation IOR yachts in comparison to traditional sailing yachts of the time and even those of a few rule-generations earlier.

Designers had carried rule-beating to the extreme of producing less seaworthy yachts.

What followed was the development of the VPP (Velocity Prediction Program) which would be used as the basis for the current IMS/ORC. The VPP that formed the basis of IMS arose out of the Irving Pratt Ocean Race Handicapping Project undertaken at MIT by J.E. Kerwin et. al., and was a monumental step forward for the sport as a whole."

Untitled Document

The CCA’s Technical Committee joined forces with the Technical Committee of the Measurement Handicap System to see what caused the Fastnet disaster. Several experts in the field of yacht design and marine engineering became central players in a study that was to last for five years. Karl Kirkman, chairman of the Sailboat Committee of the Society of Naval Architects and Marine Engineers, yacht designer Olin Stephens, Richard McCurdy, Chairman of the Safety At Sea Committee of the United States Yacht Racing Union, and Dan Strohmeier, who was a former president of SNAME, all undertook the various tasks of analyzing the design attributes, weather attributes and safety preparations. The primary focus of the study was to determine how and why so many boats capsized.

In 1985 a final report was issued by USYRU and SNAME’s Joint Committee on Safety From Capsizing. The 66-page document, which is available from the United States Yacht Racing Union (P.O. Box 209, Newport, Rhode Island 02840), details the research undertaken by the joint committee and offers several broad conclusions that help illuminate what is safe and what is not in hull and yacht design. While the focus of the work was primarily to assess the capabilities — the likelihood of capsize — on boats designed under the various racing rules, IOR, IMS and the old CCA rule, the conclusions should affect the way all sailors think about design.

The conclusions of the report, in brief, are:
……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………..
Some modern boats, which have been designed to the IOR, …. may remain inverted following a capsize.
…………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………….
The lessons learned from the 1979 Fastnet cast a pall over the design evolutions of the IOR.

The work done by the Joint Committee on Safety From Capsizing is a monument to the thought that has gone into yacht design during the 1980s.

The outcome has been a consensus among the leaders in naval architecture, in race organization and among the leading boat builders.

At the beginning of the 1990s, sailors looking for suitable, safe boats in which to go to sea inherit the benefit of all the thought and work that has taken place.

New boats coming into the market are being conceived to be stable in bad weather, to be sea kindly and to be rigged for short-handed sailing. Safety, although not heralded by boat builder’s promotion or by the sailors, is the big winner.

And, as the IOR slowly fades away, to be replaced by the IMS, sailors around the world will find ever increasingly that boats brought to them by designers and builders conform to the latest and best thinking in the safety at sea category.

Choosing a Safe Sailboat | features.boats.com

Regards

Paulo
 

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Interesting article-

Seems like for safety and easy motion they favor
long
Skinny
Deep
full keel
attached rudder
Now I wonder what rule produced those boats. :laugher
Interesting article, I agree with you on that. But it is truly amazing that you have concluded that George Day is defending Skinny, Deep, Full Keel, attached rudder, as the ideal cruising boat for all cruisers.

The article is so good that I will post the most significant parts. Please read it again, and have in mind that I have nothing against that kind of boats. If I don't particularly like IOR boats, I like very much the typical fast cruiser from the 30's to the 60's.

"Choosing a Safe Sailboat
Finding the right boat for you and your family

The choice of a boat in which to sail and cruise depends on many factors. Boats are in many ways emblems of ourselves. They reflect our sense of taste, our affluence, our experience and, most importantly, our plans for where and how we will sail……

Sailing should be fun and owning a boat is a large part of that fun. Choosing a boat that suits you and your family should place the notion of fun high on the list……

The trend to light, fast hulls that has dominated cruising and racing boats since the late 1960s, has provided sailors with boats that offer a high level of performance and ample accommodations. The evolution of hull design from full keels with keel-hung rudders has been a function of building materials and engineering as much as it has been due to innovation on the part of designers.

In the 1880s Nathaneal Herreshoff, the Wizard of Bristol, developed what may be the first small sailing vessel with a fin keel and spade rudder. He discovered that the performance of such a hull configuration outperformed every other design option of the time. Yet, a split keel and rudder did not find its way into wide use until the advent of fiberglass materials and the engineering made possible by the material.

Traditional boats of today, boats with full keels, keel-hung rudders and their propellers in an aperture, are descendants of working craft from a hundred years ago. The design is noted for its sea kindliness, it’s ability to carry heavy loads, and its slow and deliberate motion through the water. The design type evolved at a time when all boats were built of wood. The simple engineering dictates of constructing a seaworthy sailing vessel in wood led designers and builders to craft the full-keel designs we know today.

In fact, the reason Nathaneal Herreshoff’s early fin keeler did not lead to similar designs in larger, ocean going vessels was simply because the materials required to make such a vessel strong, seaworthy and safe did not exist at the time.

Yet, small boat design quickly followed Herrshoff’s lead. ... But it was not until the l960s that larger boats, ocean sailing boats, could be engineered safely using the split design type.

William Lapworth’s Cal 40, designed in the early 1960s, led the way by acquitting itself as a very fast sailing boat around the buoys, a winner of offshore races and, importantly, a safe and sea kindly vessel. The design of the Cal 40 was made possible by the extraordinary strength and forming abilities of fiberglass construction. The material permitted imaginative designers to seek new ways to make sailboats go fast, and new ways to combine speed and comfort.

The concepts behind the split keel and rudder design type gained even more notoriety and popularity when Olin Stephens created the successful America’s Cup defender Intrepid. Unlike her competitors in that season, Intrepid had a stubby fin keel, a bustle under the after quarters and had her rudder mounted at the end of the bustle well aft. Intrepid was unbeatable.

The success of the Cal 40 and of Intrepid opened many designer’s and builder’s eyes to the performance advantages of the fin keel, spade rudder design type. It was not long after that such designs became the standard, both among modern cruising boats and the racing fleet.

There is little argument today that the split keel and rudder configuration produces boats faster than configurations of the more traditional type. If speed is the first prerequisite in a boat, then lightness, minimum wetted surface and a spade rudder/fin keel design is the way to go. Yet, for those who will be sailing in conditions other than pure drag racing around the buoys there are other considerations that must go into the selection of the right boat.

The sailor who is contemplating sailing long distances along a coast or making offshore passages must look for design qualities that enhance seaworthiness, stability, the ability to carry the loads of gear, water and fuel and the ability to be handled by a small — often two-person — crew, as well as speed through the water……

The lessons learned from the 1979 Fastnet cast a pall over the design evolutions of the IOR. The work done by the Joint Committee on Safety From Capsizing is a monument to the thought that has gone into yacht design during the 1980s. The outcome has been a consensus among the leaders in naval architecture, in race organization and among the leading boat builders.

At the beginning of the 1990s, sailors looking for suitable, safe boats in which to go to sea inherit the benefit of all the thought and work that has taken place. New boats coming into the market are being conceived to be stable in bad weather, to be sea kindly and to be rigged for short-handed sailing. Safety, although not heralded by boat builder’s promotion or by the sailors, is the big winner. And, as the IOR slowly fades away, to be replaced by the IMS, sailors around the world will find ever increasingly that boats brought to them by designers and builders conform to the latest and best thinking in the safety at sea category."

Choosing a Safe Sailboat | features.boats.com

Regards

Paulo
 

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I like very much the typical fast cruiser from the 30's to the 60's.
Me too ;)- that's why I bought one. :D

here's the relevant parts:

In 1985 a final report was issued by USYRU and SNAME’s Joint Committee on Safety From Capsizing. The 66-page document, which is available from the United States Yacht Racing Union (P.O. Box 209, Newport, Rhode Island 02840), details the research undertaken by the joint committee and offers several broad conclusions that help illuminate what is safe and what is not in hull and yacht design. While the focus of the work was primarily to assess the capabilities — the likelihood of capsize — on boats designed under the various racing rules, IOR, IMS and the old CCA rule, the conclusions should affect the way all sailors think about design.
The conclusions of the report, in brief, are:
  • Larger boats are less prone to capsize than smaller boats.
  • A dismasted sailboat is more likely to capsize than a boat carrying her full rig.
  • A boat has an inherent stability range, ie. an angle of heel past which it will capsize. That stability range can be calculated from the boat’s lines and specifications.
  • Some modern boats, which have been designed to the IOR, or are designed to be particularly beamy, may remain inverted following a capsize. Boats with a stability range under 120 degrees may remain inverted for as long as two minutes.
  • Boats lying sideways to a sea, particularly light, beamy vessels, are more likely to capsize than boats that are held bow to the sea or stern to the sea. It follows, then, that boats that are sailed actively in gale conditions and breaking seas are more likely to avoid capsize than those left to lie untended, beam to the seas.
and here

Traditional boats of today, boats with full keels, keel-hung rudders and their propellers in an aperture, are descendants of working craft from a hundred years ago. The design is noted for its sea kindliness, it’s ability to carry heavy loads, and its slow and deliberate motion through the water.
and here

There is little argument today that the split keel and rudder configuration produces boats faster than configurations of the more traditional type. If speed is the first prerequisite in a boat, then lightness, minimum wetted surface and a spade rudder/fin keel design is the way to go. Yet, for those who will be sailing in conditions other than pure drag racing around the buoys there are other considerations that must go into the selection of the right boat. The sailor who is contemplating sailing long distances along a coast or making offshore passages must look for design qualities that enhance seaworthiness, stability, the ability to carry the loads of gear, water and fuel and the ability to be handled by a small — often two-person — crew, as well as speed through the water.
Don't get me wrong, I'm not "dissing" IMS. It really was an improvement. Universal rule and CCA rule produced a lot of good sea boats too. (with very high AVS's as well as good sea keeping abilities)
 

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Paulo , forgot to mention, I said this before, but I sail my own boat
at 15 to 17 degrees heel too. I can do it with whatever sail I choose to keep the boat at that heel. I get within 2/10 of my target speeds.
Of course you can. But I am not the kind of sailor (nor my family) that will sail a boat to 2/10 of its target speeds. With the cruising boats that are influenced by Open boats design, you can do 7/10 of the target speed with 17º of heel and 9/10 with 20º of heel. That is a huge difference in heel and in comfort.

No one forces you to sail at 30 degrees heel. I agree if your boat is not easily driven , you may be forced toward that end of the envelope. But to actually have to do it is typically unnecessary and certainly not comfortable.
Here we agree. But that has not only to do with the boat being easily driven.
It was mainly to do with the way the boat gets the initial stability to sail.

On large transom boats (Open inspired) the initial stability comes from hull form, and there is a lot of it at small angles of heel. On a narrow boat, initial stability comes mostly from the righting moment provided by the keel, when the boat is heeled, and it is needed a lot of heel for that force to be enough to provide the necessary initial stability for sailing at speeds near the boat potential (30º heel).

You may ask however , how one of these boats you want so much would behave if you were forced to sail at 30 degrees. You may find them unmanageable. Something I don't have to be concerned with not having a wide transom. Did you say that could be handled with twin rudders? (chuckle)
That is ridiculous. Yes, most of them have twin rudders and they are very stable going upwind. They will point less than 5º than a traditional cruiser racer, but have more sail power available (more initial stability) and can go faster at 40, 45º of the wind.

Regards

Paulo
 

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PCP said:
On a narrow boat, initial stability comes mostly from the righting moment provided by the keel, when the boat is heeled, and it is needed a lot of heel for that force to be enough to provide the necessary initial stability for sailing at speeds near the boat potential (30º heel).
yeah, that sounds about right. :D
 

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Me too ;)- that's why I bought one. :D

...

Don't get me wrong, I'm not "dissing" IMS. It really was an improvement. Universal rule and CCA rule produced a lot of good sea boats too. (with very high AVS's as well as good sea keeping abilities)
I agree with all of it. What he is saying is that there are a lot of personal choices you have to make. There are a lot of diferent types of boats that are seaworthy and the comfort and the way you like to sail, the way you have fun and enjoy sailing, is a personal choice.

In the last post you were saying that :

Seems like for safety and easy motion he is favoring favoring long Skinny Deep full keel attached rudder. Well, those too, but not only those.;)

Regards

Paulo
 

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I agree with all of it. What he is saying is that there are a lot of personal choices you have to make. There are a lot of diferent types of boats that are seaworthy and the comfort and the way you like to sail, the way you have fun and enjoy sailing, is a personal choice.

In the last post you were saying that :

Seems like for safety and easy motion he is favoring favoring long Skinny Deep full keel attached rudder. Well, those too, but not only those.;)

Regards

Paulo
I agree with that. :cool:
 

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Cormeum, (what is your first name?),

I could easily fall in love with one of these:


The photo was taken by my, last year in Porto Conte, Sardinia. We were anchored near by.

They are pure beauty to my eyes. They heel a lot, but who cares, love is irrational:D (my wife find them also beautiful). It is not the fastest type of boat around, but I am sure that sailing it would be very agreeable. But putting one of those in tip-top condition and maintaining it like that, would be out of my league.

Regards

Paulo
 

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Paulo are you actually serious with your 2/10 of target remark?
Please re read my statement

When I say I come "within" 2/10 that means if my target says I should be
making 8 knots with 16 kts true wind at 50 degrees, getting "within" 2/10
means I will be making 7.8kts

Do you actually think I would only be doing only 2 kts? meaning 2/10 "of" 8kts?

You mention:

"With the cruising boats that are influenced by Open boats design, you can do 7/10 of the target speed with 17º of heel and 9/10 with 20º of heel. That is a huge difference in heel and in comfort."

3 degrees is a "huge" difference heel and comfort??
You just said these boats are optimized for that heel, then why are they not doing 100% of their targets?

Not only are you not technical and obviously can't properly interpret a static curve, you attempt to school me and quite frankly
you sound like you have not gotten beyond a sales brochure.
 

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Regarding these wide transom boats that sail on their leeward chine ,
I guarantee you they will not repeat NOT sail with 30 degree heel.
unless they have twin rudders, I have purposely overpowered my boats
to over 40 degrees, and it remained balanced and manageable.

You can never do that and I dont care if you have 4 rudders.
You need to sail one of these or at least talk to an owner.

Then you say this " That is ridiculous. Yes, most of them have twin rudders and they are very stable going upwind. They will point less than 5º than a traditional cruiser racer, but have more sail power available (more initial stability) and can go faster at 40, 45º of the wind."

This statement makes no sense at all.

your continued digging up opinion defending these downwind race boats and theorizing these designs make for comfortable and safe cruising boats is simply foolish.

At least you should admit the compromises and stop selling these highly compromised designs to others . We all know you are sold hook line and sinker, you should leave it at that .

You also have never approached the FACT that after the IOR , static curves got worse , You continually duck this question.
The Hanse 430 curve is as bad as the worst of the late IOR curves.

The high righting arm is because it is a larger boat. It rolls off early into the danger zone. What that means is it will snap roll to a beam sea and very likely dig it's leeward rail on a big beam wave.

Wide transoms are needed for heavy air down wind work, we all know that
Foe cruising purposes where likely you are depowered, that wide transom becomes a liability.
 

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Paulo are you actually serious with your 2/10 of target remark?
Please re read my statement

When I say I come "within" 2/10 that means if my target says I should be
making 8 knots with 16 kts true wind at 50 degrees, getting "within" 2/10
means I will be making 7.8kts

Do you actually think I would only be doing only 2 kts? meaning 2/10 "of" 8kts?
Yes, you are right, I misunderstood what you have said. But what you have said and are still saying doesn't make sense.

In a boat like yours, that has a soft stability curve, the difference between 20º of heel and 30/35º roughly corresponds to 1/3 of the righting moment that is used for sailing. That is, about 1/3 of the boat "sailing power".

Pretending that 1/3 of the power will only bring the boat from 7.8 to 8.0k is absurd. You know, I sail, members of this forum are sailors, we have boats and we know that on most boats (boats designed to offer the best performance at 30º of heel) a difference of 10º of heel (and the sail power needed to accomplish that) will translate in much more than 0.2k, as you say.

In my old boat, that would be translated in about 1.5K. Of course, we are talking about sailing upwind.

Three weeks ago I have said to you:

"Post those curves of old boats that are "far superior" and we can talk and see about that."

And you have replied:

Not hard at all, My Performance Package is on board , I can scan it
or take dig photos and send as jpeg i guess.
It is not a massaged curve either like some do in hopes of getting a
category 0 or 1.
......
I will need a day or so, will see the boats tomorrow, so in the meanwhile , why don't yo do some reading since now I am working for you here . then we can amp it up a bit , if you like.
.....Kev
Three weeks later I am still waiting for the Ericsson 46stability curve. Post it, as you have said, and I will show you that the difference in righting moment between 20º and 30/35º of heel roughly correspond, in your boat, to about 1/3 of the "sailing power".


You mention:

"With the cruising boats that are influenced by Open boats design, you can do 7/10 of the target speed with 17º of heel and 9/10 with 20º of heel. That is a huge difference in heel and in comfort."

3 degrees is a "huge" difference heel and comfort??
You just said these boats are optimized for that heel, then why are they not doing 100% of their targets?
Here it is you who is misunderstanding me. I am comparing the comfort in sailing at 17º or 20º, close to the boat potential, with the comfort of sailing a boat that will only go near its potential near to 30º.

Of course, I am being honest talking about 7/10 and 9/10 of the boat speed potential (upwind) at 17º and 20º of heel, in a large transom boat, optimized to sail at 17º of heel. I don´t think we can say the same about you, when you talk of a having 8/10 of the speed potential (upwind) at 20º of heel, in a boat optimized to sail at 30º of heel. That's a 0.2k difference

Regards

Paulo
 

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Paulo,.

I take data continually with calibrated instruments, everyone is calibrated
I regularly make the numbers I post. I live for taking data and pursuing closure between theory and practice. This is what we engineers live for,
how we were born
so I would appreciate you not attempting to call me a liar.
Your assumption that heel and speed are linearly related only confirms the fact that you are not technically qualified to participate here, yet you persist.

The heel to speed relation is NON LINEAR. just like having to triple or quadruple the horsepower to just double the speed of your car.

You are constantly confused because you don't read thoroughly.
I left a trap and you failed. I said 2/10 of 8 kts was 2 ..... And it is not
It is 1.6 kts and that passed right over your head.


I did not post my curve because the Jpeg would not upload , for what ever reason , doesn't matter , you never responded until now, but I will do it again , just to show others what a healthy curve should look like.


I will post the data at my convenience, but aside from that I cannot converse with non technical people.
 
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