Clipper Ship Build Thoughts

From a quick search on the internet. Whether this is accurate or not I do not know.

An extreme clipper was a clipper designed to sacrifice cargo capacity for speed. They had a bow lengthened above the water, a drawing out and sharpening of the forward body, and the greatest breadth further aft. In the United States, extreme clippers were built in the period 1845 to 1855. British-built extreme clippers include vessels built over the period 1854 to 1870 (Annandale to e.g. Norman Court)

Extreme clippers remained in vogue only a few years. Owing to the depth and sharpness of their floors they lacked stability, and in consequence of the sharpness of the ends those parts did not have buoyancy enough to sustain their own weight—a fact which led to the straining and weakening of the vessel.
 
Early examples of the "extreme" design i.e. sharp entry, raked stem, greatest width abeam, closer to, or slightly aft of amidships and sharp exit were: the Thomas Kemp Baltimore Clipper "Grecian "of 1812; the Baltimore Clipper Ship "Ann McKim", 1832, by Issac McKim, Kennard and Williamson builders; and the schooner yacht "America", 1851 by George Steers.
The Grecian, although captured early on by the British (trapped in shore in the Chesapeake Bay)) was considered by them to be uncommonly fast.
The schooner yacht "America" blew out the competition of the Royal Yacht Squadron. When asked by Queen Victoria " Who is second?" The reply, famously, was "20230630_140437 (1).jpg20230630_133234 (1).jpg20230709_104508 (1).jpg20230709_104341 (2).jpg"Madam, there is no second." Although, later scholarship attributes much of "Americas" ' speed to her lightweight cotton sails, which also held a more efficient airfoil, allowing for greater speed close to the wind.
Ironically, the very aspects that gave the Clippers such advantage in speed, the sharp entries and exits, proved detrimental due to lack of buoyancy fore and aft, causing the ships to "hog" or droop fore and aft,
as well as having a propensity for foundering in strong following seas and rogue waves. Alas many a clipper vanished without a trace possibly due to this issue.
 
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Thanks for the replies. I read an article that said because the Flying Cloud only had a 30 inch dead rise, it was not considered a extreme clipper. Also, I read another article that stated to be considered an extreme clipper, a ship had to have a dead rise of at least 40 inches. I’m somewhat confused. My understanding is the dead rise on a ship is the angle between a horizontal line and the keel. ????

Bill
 
Bill-R said:
Thanks for the replies. I read an article that said because the Flying Cloud only had a 30 inch dead rise, it was not considered a extreme clipper. Also, I read another article that stated to be considered an extreme clipper, a ship had to have a dead rise of at least 40 inches. I’m somewhat confused. My understanding is the dead rise on a ship is the angle between a horizontal line and the keel. ????

Bill
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Bill...the *extreme* category has many interpretations...from many sources.
Several factors come into play when categorizing extreme to medium clippers.

Staghound was McKay's first extreme clipper. She had a 40 inch deadrise...was uncommonly sharp forward and aft. Great Republic had a 20 inch deadrise and she was considered an *Extreme* design. So what is it? Several factors come into play. Entry, exit and cutwater angle...to name a few.
Deadrise is the angle of the floor perpendicular to the keel head. This contributes or retracts from cargo capacity. Not to mention stability. The cutwater contributed to how she Plys the water and any effects caused by entry friction. Extreme clippers had a sharp entry and exit at the load line...and the bulk of their breadth of beam was slightly aft of amidship.

Medium clippers...such as Glory of the Seas had a very flat bottom...8 inches or so and that meant they could carry more cargo. Along with this, they had a blunter entry/exit. This contributed to fore and aft buoyancy....thus reducing the effects of hogging.

Extreme clippers were all about speed....so every engineering Trick/aspect was used to correct hogging do to fore and aft buoyancy problems.

Rob
 
Peter Gutterman said:
There seem to be a lot of weeds to get lost in in the world of Clippers. (Would those be seaweeds?) :rolleyes:
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Indeed there is......and since the *Era* lasted only 20 years....much talk has gone into what defined a clipper and those which were extreme and medium.
It's hard to find a concrete consensus on the matter....but when you familiarize yourself with the general aspects...you can generally identify between the two.

And most of all...can tell what is and is NOT a clipper. Downeaster's, or windjammers followed closely behind the clippers....but cannot be mistaken for a true clipper. Glory of the Seas, which was one of the last true clippers....actually can be labeled one of the first Downeaster's she meets the requirements of both.

What a gossamer web that is weaved........

Rob
 
Thanks Peter and Rob for the information. I spent some time trying to find a definitive answer to my question about dead rise and the best I could do is get several answers. Sometimes I tend to get focused on something that is more of a point of curiosity and end up spending a lot of time. That's what happens sometimes when you are retired. It does seem interesting that you always find the term dead rise being mentioned around the design of clipper ships, but finding out how it is calculated is difficult. I even broke out one of my marine architecture books from 50 years ago and did not find the answer. I did find one possible answer: 180 - (angle of the hull along a horizontal line from the keel) / 2. It will give you a number, but I still don't know for sure what that number represents. I could speculate on what that number is from other information I got from an internet search, but I think I've gotten too boring already.

Sorry for being long winded.

Bill
 
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In the search for "Extreme" under "Clippers" I resorted (logically, I thought) to Howard Chapelle's "The Search for Speed Under Sail".
The answer(s) I found were non-specific, vague and inconclusive. He defines clipper ships as "Large, very fast sailing ships built without much regard to cargo capacity and operating costs, which were limited to the period 1845-1855."
As to what exactly made which of these clipper ships "extreme" his suggestions (because in the aggregate that's all they are) are self-contradictory and, as I said, vague. If you want to see for yourself, see: Chapter Seven, pp. 321-2.
Rob, in post #147, comes the closest. The era defined by Chapelle as a decade, is arguably closer to two, because other clipper ships (e.g. "Glory of the Seas") fall prior to and beyond Chapelle's definition.
 
Bill-R said:
Thanks Peter and Rob for the information. I spent some time trying to find a definitive answer to my question about dead rise and the best I could do is get several answers. Sometimes I tend to get focused on something that is more of a point of curiosity and end up spending a lot of time. That's what happens sometimes when you are retired. It does seem interesting that you always find the term dead rise being mentioned around the design of clipper ships, but finding out how it is calculated is difficult. I even broke out one of my marine architecture books from 50 years ago and did not find the answer. I did find one possible answer: 180 - (angle of the hull along a horizontal line from the keel) / 2. It will give you a number, but I still don't know for sure what that number represents. I could speculate on what that number is from other information I got from an internet search, but I think I've gotten too boring already.

Sorry for being long winded.

Bill
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Here is a crude example. The greater the angle of hull the greater the deadrise.

F267C754-7290-42A2-8848-1657CB3FACA7.jpeg
 
So say the deadrise is 40”. That means if you go out from the keel till you can count 40” till you touch the hull …. You can also establish the angle, by drawing your third line of the triangle.
 
Howard Chapelle’s Search For Speed Under Sail Dates from 1967. In it he investigates the various reasons for ships being “fast.” He is writing as an Engineer. Naval Architecture is recognized as a branch of engineering. You will, therefore, not find romanticized terms; Tall Ships, Windjammer, etc among his descriptions. My guess is that he considered the adjective Extreme to have been an 1850’s marketing term to attract premium cargos and chose not to repeat it in his book. In 1967 the science of hydrodynamics was still empirical. One either copied a known fast design or carved a model and tested it in a towing tank. The theory of complex fluid flow was understood and equations were written but the math was not available to solve them. Finite element techniques awaited the development of powerful desktop computers linked to understandable graphic displays.

The book Spans a time frame of approximately 100 years and limits itself to merchant vessels and privateers. Over the 100 years, ships changed. They became larger mostly by being longer. As I have previously posted longer displacement hulls (hulls that do not plane) have higher top speeds than shorter ones. The 1812 era privateers were also built for a different job than the Clippers. Raiding a convoy and escaping from a much larger warship required superior windward performance. The Clippers were built to take advantage of prevailing winds, being better understood by the work of Mathew Fontaine Maury. Performance while reaching resulted in fast voyages. Beating to windward was to be avoided where possible.

It is possible to draw several conclusions from Chapelle’s Book:

The Clippers did not descend from the similarity named Baltimore Clippers. The hull forms of the two are different.

In addition to stowing more cargo the flat floored hull form provided much more initial stability allowing more sail to be carried in strong winds.

The much longer hulls allowed finer hull lines, and increased the top speed possible.

Fast vessels throughout the 100 year time span had straight quarter beam buttock lines aft. This would be consistent with minimizing flow separation.

Roger
 
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