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View Full Version : Re designing, engineering & testing sailing ships in the 1500's to 1800's - How was this done?


astro
06-11-2010, 01:01 AM
Assuming that most countries with large navies would want some degree of certification on the seaworthiness and performance of ship designs before committing the large funds necessary for new ships, how was this engineering and testing done in the pre-scientific method days?

Where they measured and tested, or just put in the water and hope for the best or what?

Dan_ch
06-11-2010, 06:39 AM
... or just put in the water and hope for the best or what?

Sometimes they were. The most famous is probably Vasa (http://en.wikipedia.org/wiki/Vasa_%28ship%29), which sank after sailing less than 1 mile. From the same link (bolding mine):

In the 17th century, the design requirements and calculations for building a ship only existed in the head of the shipwright. Scientific theories on vessel design or stability had not yet been developed, so important factors like the ship's center of gravity had to be estimated from the builder's experience.
...
Warships of the period, even when properly armed, were highly unstable. A major reason for this was that they were built with high aftercastles to provide a platform for soldiers to fire upon the enemy with small arms. Also, Vasa may have had the additional problem of an upper hull built with thick wale planks that were much too heavy. This might have occurred because of inexperience with two-decker ships or because of the possibility of adding even heavier armaments in the future. However, nothing is inherently wrong with the hull form of the ship; it is within the norms of the period.

Hypno-Toad
06-11-2010, 07:24 AM
Many of the great scientific minds of the enlightenment and early scientific era worked on ship design. Much of the effort was, of course, wrong. But that's par for the course with trial and error. The French were some of the earliest to institutionalize ship research. They built the first towing tanks for testing ship models. And the late 18th century saw scientists and mathematicians all over Europe trying to calculate water resistance on various hull forms. One (Wrong) theoretical approach was to treat resistance as the sum of all the water particles striking the surface of the hull. They began reducing the hull to a surface of triangular shapes and calculating the resistance of each one. and The French govt. started requiring ship builders to supply these calculations on their plans. It was known that the French were doing this and it's one reason why their shipbuilding was highly regarded.

I'm getting all this from: Ships and Science: Naval Architecture in the Age of Discovery1600-1800 by Larrie Ferrerio. It's a good book if you can either understand or ignore the math. I had to ignore it.

Hypno-Toad
06-11-2010, 07:47 AM
I forgot: Here's an awesome site. (http://www.hnsa.org/doc/steel/) It's a scanned and internally linked text on ship design and tactics from 1794. Some of the drawings and plans of masts and spars are pretty cool and it goes into detail on things like rope-making and manuevering ships in formation. It takes a bit of study because the 18th century maritime lingo comes at you pretty hard and fast.

Floater
06-11-2010, 08:52 AM
From the wiki article about the Vasa: "had insufficient ballast". IIRC she had no ballast at all at the time.

This_Just_In...
06-11-2010, 10:31 AM
I don't think many ships came out of the dockyards anywhere near being as efficient as they could be.

From what I understand field modifications took place all of the time. Not to the hull so much, but to the sails, spars and even masts. Remember these ships would made out of wood and there were often several skilled carpenters, sailmakers etc. onboard. Captains would try modifications (not blindly but based on experience) and would be quite pleased if they could achieve a faster speed for some particular point of sailing.

Early hulls were also designed with high bow/sterns (awkward) intentionally - to help with both offensive and defensive combat by providing a way to gain a height advantage against enemies. Of course the high sides negated much of the sailing efficiency. This went away somewhat as cannon power became more efficient and a battle could be won without boarding the other ship.

Hypno-Toad
06-11-2010, 11:44 AM
Here's a wiki link (http://en.wikipedia.org/wiki/Original_six_frigates_of_the_United_States_Navy) about the original six frigates of the US Navy. It has some good detail about ship building with pre-literate methods. Things like the use of models and molds to create full-size pieces.

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