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help reading dimensions on an old blueprint

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help reading dimensions on an old blueprint

Old 06-06-2011, 01:13 PM
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Default help reading dimensions on an old blueprint

I picked up a blueprint for a small skiff that was hand drawn in 1982. The dimensions are listed different than I have ever seen. They are shown "1-8-4" My understanding is the first digit is feet, the second inches, but the last I don't know. Would it be 1/4s or 1/8s or something different entirely? Thanks in advance for the help
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Old 06-06-2011, 01:18 PM
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got me on that one maybe a fraction of a inch
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Old 06-06-2011, 01:53 PM
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Originally Posted by ADAM87 View Post
I picked up a blueprint for a small skiff that was hand drawn in 1982. The dimensions are listed different than I have ever seen. They are shown "1-8-4" My understanding is the first digit is feet, the second inches, but the last I don't know. Would it be 1/4s or 1/8s or something different entirely? Thanks in advance for the help
Those numbers look like standard fare from a table of offsets - back in the day when hulls were actually lofted.

There should be a legend telling you what the order is, but standard is Feet Inches 8ths. So, your numbers would be 1ft + 8 inches+4/8 inches
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Old 06-06-2011, 02:42 PM
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I've been around blue prints forever. I've never seen it like that.

I could believe that Mod 2 is correct but what does the print scale out at? All prints are drawn to scale.
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Old 06-07-2011, 04:29 AM
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Here's a good link........http://forum.woodenboat.com/showthre...es-of-offsets&
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Old 06-08-2011, 03:18 PM
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The last digit is 16ths. So the dimension is 1'-8 and 4/16ths" (1/4). This is a common dimension system used to this day by truss designers.
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Old 06-08-2011, 03:42 PM
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Originally Posted by davidd View Post
Originally Posted by buzzellc View Post
The last digit is 16ths. So the dimension is 1'-8 and 4/16ths" (1/4). This is a common dimension system used to this day by truss designers.
The above link agrees with Mod 2 on it being 8th's(and + or - 1/16) and so does one below(had to look it up too)


If there's a "1-8-(8-15)" on the plans anywhere then it would have to be 16ths.


The figures in the grid are measurements that correspond to points on the lines, which are then joined to make the smooth curves that make up the plan. The figures in the grid are in the form "3-8-4" which if you look in the lower left corner of the table of offsets, you can see means "Ft. Ins. 8ths", so 3-8-4 means "3 feet + 8 inches + 4/8 inches".


http://modelshipsecrets.blogspot.com...f-offsets.html
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Old 06-09-2011, 05:29 AM
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Scale on print is 1"=1'0" but I don't see any key/legend for the dimensioning. But I can't see why it would be anything tighter in tolerance than 1/8's. Thanks for the help guys.
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