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Old 01-05-2015, 16:24   #346
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Re: The criteria of "blue"

The OP should also read,
Seaworthiness : The Forgotten Factor [Hardcover] [1996] (Author) C. A. Marchaj: Amazon.com: Books. This book is an eye opener for many reasons. There is some math in the book, simple stuff though, and it can be skipped. It is interesting to note the hull designs, including rudders, that are considered modern, where being built well over a century ago.

While this book does not dive into boat design detail but it is the single best book I have read about cruising:
The Voyager's Handbook: The Essential Guide to Blue Water Cruising: Beth Leonard: 9780071437653: Amazon.com: Books

Later,
Dan
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Old 01-05-2015, 16:33   #347
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Re: The criteria of "blue"

The real issue at hand, and my original question, ....are 'lifting keel' sailboats genuine blue? Let's take the Cheeki Rafiki example, is a lifting keel more or less 'stronger' than what was found on the 40.7 Benny?

(On the newer Seaward 46's, you can lift the keel manually with a wrench.)
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Old 01-05-2015, 16:47   #348
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Re: The criteria of "blue"

Yes.

Marchaj wrote interesting things backed by examples of boats and some theoretical musings. It is a fine book. His books on hydrodynamics of the hull and aerodynamics of the sail are also great read.

Alas.

I think my all time favourite in respect of offshore / cruising writings is OCE by the Dashews. The chapters on structures, engineering, construction, design and surviving a knockdown I can read, re-read and then re-read again. Great pieces from people who sailed, then designed, then sailed what they designed and then they improved things. They live what they pray. If sailing were a Roman-styled religion, the Dashews would be amongst our gods. ;-)

Read some, sail some, write some!

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b.
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Old 01-05-2015, 16:56   #349
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Re: The criteria of "blue"

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Originally Posted by dannc View Post
The OP should also read,
Seaworthiness : The Forgotten Factor [Hardcover] [1996] (Author) C. A. Marchaj: Amazon.com: Books. This book is an eye opener for many reasons. There is some math in the book, simple stuff though, and it can be skipped. It is interesting to note the hull designs, including rudders, that are considered modern, where being built well over a century ago.

While this book does not dive into boat design detail but it is the single best book I have read about cruising:
The Voyager's Handbook: The Essential Guide to Blue Water Cruising: Beth Leonard: 9780071437653: Amazon.com: Books

Later,
Dan
Thanks Dan
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Old 01-05-2015, 17:43   #350
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Re: The criteria of "blue"

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The real issue at hand, and my original question, ....are 'lifting keel' sailboats genuine blue? Let's take the Cheeki Rafiki example, is a lifting keel more or less 'stronger' than what was found on the 40.7 Benny?

(On the newer Seaward 46's, you can lift the keel manually with a wrench.)

Lifting keels are predominantly used by serious cruising boats - so they have blue credentials. There are several variants on the same theme though.

Some are just fins and the righting stability is derived from a low center of gravity set deep in a ballasted hull. Advantage is that there is not much noticeable difference with keel up or down so you get minimal CG change in either mode and therefore you do not need to worry about boat trim so much and get a benefit down wind through less drag on the fin coz its not needed for boat stability. - you can lift it up.

Then you get the other type that carries the counter weight in the keel itself like a normal keeled boat. Advantage is that because you can carry the weight lower the righting moment is greater and the boat will heel less. On this type of keel you have to incur some drag cost down wind though else it gets a bit wobbly. Runs closer to the wind but another disadvantage of a weighted swing keel is that you change the CG of the boat when the keel is up or down and at all points in between.

The connection mechanism is inside a cassette in the hull and you get variants of design here also. Swing keels are on an axis an offer some shock resistance if they connect underwater with something. The other type is as we see in the Seaward 46rk written about today which is a lifting keel. To lessen the CG issue mentioned they rise up and down in a tall sleeve but offer not much shock resistance as they can not of course swing backwards. That Seaward had the keel nearly ripped out as i think the skipper may have used it to try and pin himself down when the boat was heading out of control to the shore.

For my money I would get a fin swing keel but you would lose room in the salon and be limited for choice on salon configuration coz that keel has to of course sit center line. Also with the fin swing keel I would loose some righting moment but I think it is the strongest, safest and the least complicated compromise all round.

I like the idea of a dynamic keel but not the idea of lifting a lot of weight that could also become lateral pendulum and require complex engineering to prevent it.

So in summary with a fin swinging keel your question about strength is negated some what because the fin has minimal weight. the keel is in effect inside the boat which means in shallow waters you can run with full sail. With a weighted swinging keel though you dramatically change the righting characteristics when the keel is up so you might fall over if there is a strong blow. Would need to use less sail or just motor.
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Old 01-05-2015, 19:00   #351
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Re: The criteria of "blue"

Wasn't the trimaran a good blue water boat... until it got torched?

http://endacunningham.ie/wp-content/...waterworld.jpg

Sent from my SAMSUNG-SGH-I747 using Cruisers Sailing Forum mobile app
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Old 01-05-2015, 20:18   #352
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Re: The criteria of "blue"

Do we think the Garcia 45 is the modern day Baba 40 ?
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Old 01-05-2015, 21:48   #353
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Re: The criteria of "blue"

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Originally Posted by paulanthony View Post
Lifting keels are predominantly used by serious cruising boats - so they have blue credentials. There are several variants on the same theme though.

Some are just fins and the righting stability is derived from a low center of gravity set deep in a ballasted hull. Advantage is that there is not much noticeable difference with keel up or down so you get minimal CG change in either mode and therefore you do not need to worry about boat trim so much and get a benefit down wind through less drag on the fin coz its not needed for boat stability. - you can lift it up.

Then you get the other type that carries the counter weight in the keel itself like a normal keeled boat. Advantage is that because you can carry the weight lower the righting moment is greater and the boat will heel less. On this type of keel you have to incur some drag cost down wind though else it gets a bit wobbly. Runs closer to the wind but another disadvantage of a weighted swing keel is that you change the CG of the boat when the keel is up or down and at all points in between.

The connection mechanism is inside a cassette in the hull and you get variants of design here also. Swing keels are on an axis an offer some shock resistance if they connect underwater with something. The other type is as we see in the Seaward 46rk written about today which is a lifting keel. To lessen the CG issue mentioned they rise up and down in a tall sleeve but offer not much shock resistance as they can not of course swing backwards. That Seaward had the keel nearly ripped out as i think the skipper may have used it to try and pin himself down when the boat was heading out of control to the shore.

For my money I would get a fin swing keel but you would lose room in the salon and be limited for choice on salon configuration coz that keel has to of course sit center line. Also with the fin swing keel I would loose some righting moment but I think it is the strongest, safest and the least complicated compromise all round.

I like the idea of a dynamic keel but not the idea of lifting a lot of weight that could also become lateral pendulum and require complex engineering to prevent it.

So in summary with a fin swinging keel your question about strength is negated some what because the fin has minimal weight. the keel is in effect inside the boat which means in shallow waters you can run with full sail. With a weighted swinging keel though you dramatically change the righting characteristics when the keel is up so you might fall over if there is a strong blow. Would need to use less sail or just motor.
thanks a lot for explaining that to me. in my case, i won't be crossing any oceans where i could get stuck in some awful weather. someone once said, 'the most dangerous thing on a boat is a schedule.'
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Old 02-05-2015, 07:26   #354
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Re: The criteria of "blue"

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thanks a lot for explaining that to me. in my case, i won't be crossing any oceans where i could get stuck in some awful weather. someone once said, 'the most dangerous thing on a boat is a schedule.'
Sounds like a quote worth remembering.
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Old 02-05-2015, 08:26   #355
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Re: The criteria of "blue"

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...
Alas.

I think my all time favourite in respect of offshore / cruising writings is OCE by the Dashews. The chapters on structures, engineering, construction, design and surviving a knockdown I can read, re-read and then re-read again. Great pieces from people who sailed, then designed, then sailed what they designed and then they improved things. They live what they pray. If sailing were a Roman-styled religion, the Dashews would be amongst our gods. ;-)

Read some, sail some, write some!

Love,
b.
I have read three of the Dashew's books, including Offshore Cruising Encylopedia, and it was a first class act on their part to release for a free download their storm tactics and weather books.

I really value their opinion. OCE is a treasure trove of information about boats and cruising. I can't remember if it was available for Kindle but I bought the physical book because it is a book that should be on the boat.

Having said that, , it is one thing to take what they say or build, and have someone else build to their standards. Their boat designs are very well thought out and built but getting someone else to replicate what they do would be problematic. We want a trawler, and while I do like the exterior of the FPB 64, I don't like the interior plan and the boat is too danged big. Tis a moot point since we can't afford an FPB 64. The wifey and played the what if we won the lottery game, would we buy the FPB 64, and the answer was no. We really like the boat we want to buy. The FPBs are great boats from a technical and build point of view that really impress me. I just don't want one. Go figure.

The FPBs ARE blue water boats for sure.

Later,
Dan
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Old 02-05-2015, 08:51   #356
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Re: The criteria of "blue"

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I have read three of the Dashew's books, including Offshore Cruising Encylopedia, and it was a first class act on their part to release for a free download their storm tactics and weather books.

I really value their opinion. OCE is a treasure trove of information about boats and cruising. I can't remember if it was available for Kindle but I bought the physical book because it is a book that should be on the boat.

Having said that, , it is one thing to take what they say or build, and have someone else build to their standards. Their boat designs are very well thought out and built but getting someone else to replicate what they do would be problematic. We want a trawler, and while I do like the exterior of the FPB 64, I don't like the interior plan and the boat is too danged big. Tis a moot point since we can't afford an FPB 64. The wifey and played the what if we won the lottery game, would we buy the FPB 64, and the answer was no. We really like the boat we want to buy. The FPBs are great boats from a technical and build point of view that really impress me. I just don't want one. Go figure.

The FPBs ARE blue water boats for sure.

Later,
Dan
Yep. you are quite right. Often what is good for us just does't always taste or look so good.
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Old 02-05-2015, 14:24   #357
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Re: The criteria of "blue"

I've gained very valuable info from this thread (thanks) so I'd like to try to summarize a bit of it for others who are also currently researching the market, feel free to correct. Nothing much new here either so some may want to skip this:

1. Strength
Some aspects of strength can be seen and others can't. Skegs and rudders are a great example of the former (now we know what to look for); bulkhead attachment, skin thickness, equipment attachment, etc, may require careful research or a good surveyor. Yachts built to a standard should have sufficient hull strength, so make enquiries.

2. Layout
This was well highlighted in the discussion. Think how those split levels, sharp corners, lack of handholds, ballroom saloons would look in rough weather with water coming down the hatch and clobber falling out of lockers, not how they look at the boat show.

3. Stability (the most controversial aspect so far)
This is important and blue demands more of it than non-blue.
Capsize Screening Factor (CSF) is a near-meaningless measure that takes no account of weight distribution.
Angle of Vanishing Stability data should be available for most modern yachts, either from IMS data or ISO (if not then suspect the worst or ask). It varies between 100-140 (though 170 and even 180 do exist!). The general consensus (read Doane and others) is that 120 is a minimum for blue, considerably less for non-blue (a little less if you choose to go super-large but still critical for anything less than a freighter). Note that about half the yachts for which data is available fail to meet this requirement of blue.
STIX is more controversial, but being required info for any builder selling to the EU, it is a commonly available measure that some may find useful for comparison of a factor which is otherwise very hard to quantify - downflooding angle may be obvious but many other components of this complex measure are not, so take it or leave it but at least it should be discussed as one factor available for comparing different designs of blue. 35 (or is it 38?) is the cut-off for blue, but some say 40 should be the figure. Check it out - you'll be surprised which yachts don't make the grade, some by a very large margin!

4. Incompetent builders
Look for tell-tale signs of incompetence (fuel vents on outside of hull!!!) then walk away.

5. Cruising style
Some cruisers plan to cruise a particular area with which they will in time become very familiar, others have mentioned very adventurous plans(!). Deep fin and spade (or lift keel in some areas) may prove more suited to the former cruising style, full keel and barn door rudder, or long cruising fin and substantial skeg (not those skinny ones!), may be better suited to the other group, where grounding is "inevitable" (it's not if, but when), as the main difference between spade and barn door will be the ability to continue after some serious encounters with coral.

Is this a fair summary or am I still showing bias? What have I forgotten?
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Old 02-05-2015, 15:02   #358
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Re: The criteria of "blue"

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(...)

1. Strength
Some aspects of strength can be seen and others can't. Skegs and rudders are a great example of the former (now we know what to look for); bulkhead attachment, skin thickness, equipment attachment, etc, may require careful research or a good surveyor. Yachts built to a standard should have sufficient hull strength, so make enquiries.

(...)
Yes.

Strength is essential. And as much as it is essential, it is often misunderstood. Too bad so very few sailors are pilots.

Strength starts on the designer's desk, and this designer's skills and experience are of paramount importance. We may always look up to racing designers for this. A designer who only designs cruising boats may (not = will) derive strength from different paradigms than the racing designer.

So to say, we can have light and strong or we can have heavy and strong. The huge difference between the two being that the light one will be easily driven while the heavy one will be slow and effort-hungry.

Not to say any of the combinations is better than the other, only to point out that where the strength is derived from will have major consequences in respect of how the boat sails and how difficult it is to sail long (possibly ocean) passages in it.

b.
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Old 02-05-2015, 15:54   #359
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Re: The criteria of "blue"

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..... Is this a fair summary or am I still showing bias? What have I forgotten?
In this BW Criteria Summary... I would add MAINTENANCE HISTORY to the list.

In my early years of yacht delivery I discovered that a weak but well maintained boat was far more reliable than a strong but neglected one.....
Poor maintenance has an accumulative effect to destroy any quality build.
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Old 02-05-2015, 16:18   #360
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Re: The criteria of "blue"

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In this BW Criteria Summary... I would add MAINTENANCE HISTORY to the list.

In my early years of yacht delivery I discovered that a weak but well maintained boat was far more reliable than a strong but neglected one.....
Poor maintenance has an accumulative effect to destroy any quality build.
and the defects can cost a bucket load of money to rectify.

A while back there was a poll on CF asking the age of people's boats... a fair percentage were 30 year old or more.

That fine by me but I imagine many of those boats have been owned by the pollees for quite a long time. Mine for instance is 28 yo but I have owned her for 21 years.

I would suggest considerable caution be exercised by anyone considering a v old boat... good design/build or not... all too often they may be getting sold by someone who lost interest quite some time back.

As my number one pup said a while back re 'stuff' in general.... 'old people think everything has value while in fact - these days - a lot of stuff has negative value and you will have to pay someone to take it off your hands'

Holds true for boats as well......
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