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10-20-2011
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Hi Paulo
Very interesting information on hull speed - thanks very much!
David
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10-20-2011
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Quote:
Originally Posted by slap
Paulo -
In a recent post, you gave two different definitions of prismatic coefficient - one was not correct.
This one is incorrect - this one is the definition of block coefficient.
Quote:
Prismatic Coefficient is a mathematical measurement of the relative shape of the bow and stern of the boat. It displays the ratio of the underwater volume of the hull relative to a rectangular block.
And this is the correct one:
Quote:
We express the "full hull" property by the prismatic coefficient, which is the ratio of volume displaced to the product of waterline length and maximum cross-sectional area.
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Slap, I was quoting, not giving definitions and both quotes seems correct to me. The problem here is that is difficult to translate mathematical definitions to words.
In fact both the Prismatic coefficient and the block coefficient are ratios to a box or a prismatic figure as you want to put it.
Block Coefficient... If you draw a box around the submerged part of the ship, it is the ratio of the box volume occupied by the ship.
Prismatic Coefficient... It displays the ratio of the immersed volume of the hull to a volume of a prism with equal length to the ship and cross-sectional area equal to the largest underwater section of the hull (midship section).
http://en.wikipedia.org/wiki/Hull_(watercraft)
These drawings explain it clearly:
http://www.marinetechs.com/Definitions,27
The guy you have said that had given an incorrect definition explains it more detailed (and correctly) on the linked text with this figure an comments:
From the diagram, the longitudinal Cp = Volume / (Am x Lpp) Volume = volume of hull at draft T Am = midship section area (at given draft T, in figure) Lpp = length between perpendiculars.
http://nasailor.com/2011/06/05/boat-...c-coefficient/
Regards
Paulo
Last edited by PCP; 10-20-2011 at 09:12 AM.
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10-20-2011
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Last edited by PCP; 10-20-2011 at 07:32 AM.
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10-20-2011
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New 360º photo for the Salona 38. Inside and outside, lots of views.
360 - Salona Yachts
The design and quality are good but they have to find another upholsterer  . The cushions don't match and that's not the first time that I have saw that on a Salona. How difficult is that?  .
The head on the three cabin boat (this one) is too small. It is a good one on the two cabin boat.
Outside the cockpit is really great, except that table that the only advantage is that it can be taken away and mounted in no time. I know that they are studding a new one, hopefully better looking and with handholds for the ones that sail with the table on (it will also be a removable one).
Also a movie taken by the magazine Vela in the Genova boat show:
Salona 38 new.wmv - YouTube
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10-20-2011
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The same for the Xp 38, I mean, the movie made by the same magazine in the Genoa boat show. They don't have yet a 360º photo of this one.
Xp 38 new.wmv - YouTube
The cockpit is very similar to the one from Salona and I just love the bowsprit. They guys from Salona are working in one for the 38 and I can just wait that it looks as awesome as this one.
The quality looks good but the Salona is warmer and the cabin of this one looks smaller. I guess that is because they have the head not in front but in the boat center and that makes the saloon smaller. This head is bigger than the one in the three cabin Salona (this is also the three cabin version), but smaller than the one in the Salona two cabin version.
Funny, I cannot find on the x yacht site the drawings for the two cabin version. This is the only version?
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10-21-2011
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I have not yet posted about Shipman and that is strange because they are among the sailboats I like more  . If I had a lot of money this would be probably on my short list because they are beautiful, fast, small draft (lifting keel), with great panoramic interiors, a lot less expensive than custom made boats and are designed to be solo sailed. That ability to be sailed solo or with a very small crew is very rare among big sailboats, and the Shipman are big. The Smallest is a 63ft.
On the year that they made that one it won the European boat of the year contest in its category and I remember that the one that was second, the Halberg Rassy 54 had an higher price (or costed about the same?). Anyhow I remember having been surprised by the "low" Shipman price, specially because this is a carbon boat and a Danish one and Danish boats are normally expensive boats (the Shipman is not built in Denmark)
Take a look at some photos of some of their boats:
 The 72fter
 The 80ft
 80ft
Take a look at these movies about the 80ft and the 63ft:
Shipman 80 - official video - YouTube
ASW 2011 Antigua Sailing Week 2011 Shipman 63 boat speed 21kts - YouTube
They say about their boats:
We had a vision.
We wanted to create a sailing yacht for visiting the world’s most attractive cruising grounds that would be indulgently relaxing, comfortable and yet would not sacrifice the feel and speed of a racing craft. She would need to be reliable and seaworthy in all conditions, simple to control and capable of sustaining high speeds under sail or engine for an extended period, with a minimal crew.
It should be of sophisticated design, yet simple to maintain.
It should be fast, but easy to control.
It should be stable, but still capable of exploring shallow bays.
It should make life for the owner easy and stress free.
It should be of sufficient strength, range and equipment to allow a summer in the Med, a winter in the CARIBBEAN and two transatlantic crossings per year, all without effort and stress.
A Shipman is defined as a single-handed pilothouse high-performance yacht.
Fast and strong, seaworthy, easy to sail and handle, functional and good looking, she is the racer's world cruiser.
In recent years, advances in technology have led to dramatic improvements in performance. Offshore multihulls, Open 60s and Volvo racers have smashed all records and set the standards of ocean-going speed to new and incredible levels.
The secret of these racers' speed potential lies in a new technology developed around two materials: CARBON fibres and EPOXY resin. When resin systems are combined with reinforcing fibres such as carbon, exceptional properties can be obtained. The resin matrix spreads the load applied to the composite between each of the individual fibres and also protects the fibres from damage caused by abrasion and impact.
These modern materials give a stronger and stiffer boat and are the key factor in the dramatic increase in performance of today’s racing boats. The use of these exotic materials is the main price-influencing factor (together with the carbon rig) but the only way to lower displacement, bringing easy handling and high performance.
For this reason, these materials have, until now, only been available to those with a one-off budget. But now, Shipman has made a series of important developments in the design and building process to enable the production of a high-tech, high-performance yacht at moderate cost. All Shipman carbon yachts incorporate these new techniques to redefine cruising performance without compromising safety or durability.
But of course if the 80ft is not big enough to you they had proposals till the 150ft sailboat.
Just look at the 130ft boat, that is able to make 9k speed with 6k wind and 12kspeed with 8k wind. About max speed with strong winds I don't know but the small one (63fr) is able to do over 20K. Regarding the max speed on the 80ft, I just don't know but I dare to say that will be a lot more than 20K.
Of course if you want to go faster you have just to have the 150ft
Last edited by PCP; 10-21-2011 at 04:44 PM.
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10-21-2011
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Do you know Shaw boats?
They are designed and made by Robert Shaw and they are mostly racers, interesting and fast boats, with a cruiser-racer on the line and if some think that I post some radical performance cruisers take a look at the numbers of this one:
Principal Dimensions
LOA 10.6m
LWL 9.8m
Beam 3.2m
Draft 3m
Displacement 2800kg
Sail Area
Upwind 84m2
Main 51m2
Jib 33m2
Gennaker 160m2
They say about the 10.6m Cruise/Race
The Shaw 10.6 Cruise/Race is designed for harbour and coastal racing, with the ability to go offshore in races such as Auckland-Fiji. It has a canting keel, and can be cruised or raced short-handed by two crew or fully crewed with up to eight sailors. It has a moderate-volume interior which makes for comfortable cruising without comprimising race performance.
But most of them are coastal racers with the exception of this one , the 9m that is not only designed for coastal racing but as also the ability to go offshore in races such as Auckland-Fiji or the Transpac.
It has a canting keel a forward canard or twin dagger boards and needs a four or five crew to tame it
http://www.youtube.com/watch?v=CONl4...eature=related
But all of them look beautiful to me:
The smaller ones, like this one, are a bit wet to sail even if great fun:
To see what I mean just see this movie, it is hilarious     :
Monkey Business at Airlie 2011 - YouTube
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Last edited by PCP; 10-21-2011 at 08:27 PM.
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10-21-2011
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Quote:
Originally Posted by PCP
...the Shipman are big. The Smallest is a 63ft.
On the year that they made that one it won the European boat of the year contest in its category and I remember that the one that was second, the Halberg Rassy 54 had an higher price (or costed about the same?). Anyhow I remember having been surprised by the "low" Shipman price, specially because this is a carbon boat and a Danish one and Danish boats are normally expensive boats (the Shipman is not built in Denmark
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European boat of the year was...
Shipman 50 concept was born in 2001. The idea of a new singlehanded high-performance pilothouse offshore cruiser was developed by Joergen Bonde, the Danish owner of Shipman Yachts, and Jernej and Japec Jakopin of Slovenian J&J Design/Seaway. The carbon/epoxy prepreg technology was generously transferred by Bill Green of Green Marine in Lymington (UK), and the materials engineering and supply came from Giovanni Belgrano of SP Systems in Cowes (UK). The result surpassed expectations : Shipman 50 was elected the overall winner of European Boat Of The Year 2003 contest by 11 votes coming from 11 participating countries in January 2004. Shipman 50 was faster, more easily handled, stronger and more comfortable than any comparable boat giving new feeling of performance and enjoyment to cruising and club racing. 11 boats were sold to 9 countries. Complete tooling set was lost in a fire on April 11th 2007.
Today several used Shipman 50 are for sale (priced at 700k EUR). As far as I remember new Shipman 72 price was +4 mio EUR and Shipman 63 +2.5 mio EUR. This price tag probably "low" for Russian oligarchs as majority of Shipmans are owned by them.
Take a look at this post of new Shipman 80 launch. Also if interested check blog of this Russian Shipman 72 skipper (he is also Shipman dealer). Unfortunately blog is in Russian, but almost every post comes with nice pictures.
Also take a look at red Shipman 72 'Moksha' gallery and don't forget to check the wall with news like "we broke Moksha's personal speed record maxing out at 22.2knots" 
Last edited by G1000; 10-21-2011 at 10:53 PM.
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