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Old Oct 30, 2012, 08:54 AM
MMangus is offline
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Sport R/C Flyer/Sailer/Driver
United States, MS, Columbus
Joined Nov 2001
263 Posts
One of the more annoying issues I came across while researching the French ship Le Requin was the difference in displacement and weight. Different sources would list the same number but in a different context, i.e. 220 tons or 220t displacement. When trying to figure out the weight of a 1:48th scale model of the ship, the calculated scale weight kept coming out to around 5 pounds ... much too light from my expirience with 1:144 scale ship models.

It took some digging, but I eventually managed to figure out that before the mid 1800s, ship weight was usually measured in actual weight and not displacement. When iron clads and iron ships revolutionized warships in the late 1800s, designers started using displacement (the weight of water displaced by the hull) versus actual hull weight. Using a similier sized 1:144th 1905 warship hull for comparison, I eventually guestimated a 8 pound model weight for the 1:48th scale Le Requin. The model finished up within a half pound of that guess at 8.5 pounds.

So what does all of this mean? Welp, it seems that depending on who drew what plan and what thier information source was may have confused actual weight and displacement weight. If displacement weight is assumed, chances are the calculated model weight will be lighter than if actual weight was used. Such was the case with the Le Requin. It is probably safe to say that any weights given for a pre-1850 ships is most likely actual weight and not displacement weight.

As a side note on ship evolution; until the mid 1800s, ship evolution could be measured in hundreds of years. It was slow. A ship design was more likely to change to address a practical need versus a performance enhancement. Such as is the Korean Turtle ship, originally designed in the 15th century and built to counter Japanese pirates in the 1500's. Yet over the next 200 years the Turtle ship remained essentially unchanged because there was no reason to change it, no outside influeance to force the Koreans to change the design.

It was not until iron ships and steam propulsion arrived on the scene that ship evolution accelerated to breakneck speed compared to the previous few hundred years.
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