metric Vs english syst.

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sal
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metric Vs english syst.

Post by sal » Tue Dec 04, 2018 12:55 pm

I went to order plans and noticed I can have metric or English measurements -any thoughts on which might be better for amateur building (which may be more forgiving ,more accurate ) ? thanks Sal



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Re: metric Vs english syst.

Post by Jeff » Tue Dec 04, 2018 12:57 pm

Sal, both US & Metric are quite accurate so just go with whichever you are more comfortable with. If you plan to scale up or down then Metric are normally easier to work with!! Jeff

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Re: metric Vs english syst.

Post by jacquesmm » Tue Dec 04, 2018 1:54 pm

Correct and there is a secret: you must choose between the two systems if you order printed plans but the PDF files always include the two sets.
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Re: metric Vs english syst.

Post by Jaysen » Tue Dec 04, 2018 2:42 pm

Does it matter if one buys the CNC kit? I'm thinking about the various parts that need drilled to fit but have a "distance from edge" that needs to be accounted for )mast partner on the v12 for example).
Jaysen wrote:
Mon Apr 29, 2019 3:44 pm
I tried to say something but God thought I was wrong and filled my mouth with saltwater. I kept my pie hole shut after that.

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Re: metric Vs english syst.

Post by jacquesmm » Tue Dec 04, 2018 4:05 pm

No, it does not matter. All dimensions are always the same, it is only the text tolerance that differs.
The kits are cut directly from the CAD files, no dimension text is used.

Let's try to explain that differently and take the opportunity to clear up something.
See the dimensions below:
Image

The dimension on the left is 15.11259, the exact length to the 5th decimal, very accurate. That is what Eric would use in his machine shop but we don't cut plywood to the 5th decimal. The CNC machine uses the first 3 decimals because we need precision for the puzzle joints.
On the right are the dimensions as printed on the plans, with the text rounded up to something practical: 1/8" or 1 mm. Each is sufficiently accurate for our building method. I do not want to give the impression that the builder must cut his plywood with more precision and it keeps the drawings simple.
If you want to compare between systems, the metric is more precise because it is rounded up to 1 mm and 1/8" is about 3 mm but please do not try to draw the panels or cut the plywood with that much precision, it is a waste of time.
We can say that the CNC kit will be more accurate but it does not matter.

That rounding up has consequences and in some cases, builders have noticed discrepancies because I don't use cumulative dimensions, , see below.

Image

The long line is made of 2 segments each exactly 15.060" (15 inches and 60 thousands).
When I show the dimensions for one, rounded up to the closest 1/8, it becomes 15" each but the dimension for the two combined becomes 30-1/8. The "real" length is 30.120" , rounded up to the nearest 1/8, it becomes 30-1/8".
It looks strange but each is correct with a 1/8" tolerance.
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Jaysen
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Re: metric Vs english syst.

Post by Jaysen » Tue Dec 04, 2018 4:11 pm

I completely understand. Thank you!
Jaysen wrote:
Mon Apr 29, 2019 3:44 pm
I tried to say something but God thought I was wrong and filled my mouth with saltwater. I kept my pie hole shut after that.

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Re: metric Vs english syst.

Post by fallguy1000 » Tue Dec 04, 2018 5:27 pm

It is easier to build in metric.

As an imperial system wizard, I can tell you base two has a place in building-houses.

But for boat building, once you get the hang of metric; it's benefits become clear.

My laser level yesterday..went to check the height differences on four corners of the cockpit and they were 680, 680, 684, 686.

In English, 680mm is 26 3/4+, 686 is 27, 684 is 26 15/16 or so. The ability to understand Metric comparitively is much easier.

The one thing that sucks qbout Metric is the best tape I have found is very poor and requires two to operate more than 4 feet away AND it is imperial on the opposing side, so anytime I absolutely need to use the other side of a tape; back to Imperial.

Easier to build it Metric, but it takes awhile to develop any intuition if you are only familiar with Imperial.
My boat build is here -------->

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Re: metric Vs english syst.

Post by Fuzz » Tue Dec 04, 2018 6:18 pm

I used to work in the oilfield drilling wells. You must have accurate pipe measurements to do down hole work. So each joint of pipe is measured before going in the hole and a tally is kept. Can you imagine trying to add up 400 joints of pipe using 1/16ths. 30 feet four and 3/16 inch plus 31feet 2 and 1/2 inch and so on. So instead they measure the foot in hundreds. Reads like this 30.89 plus 31.26 and so on. To me it just shows how much simpler the metric system is.

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Re: metric Vs english syst.

Post by cape man » Tue Dec 04, 2018 6:50 pm

Pop quiz...I work with fish farms (that's the hint :lol: ). We commonly use 0.0038 as a conversion factor in dosing drugs and chemicals. Any guesses on what that equals?

2.72 is another number that equals the same thing but with a different foundation.

I love metric, but am forced to work in ancient English as well.
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Re: metric Vs english syst.

Post by terrulian » Tue Dec 04, 2018 7:04 pm

When I was in high school in the early sixties I was taught that the metric system was coming soon. But no.
I found this bit in an article about what happened to the metric system in the US, which was moving forward under Ford but quashed under Reagan:
But that continental arrogance didn’t play as well in America. Particularly in wounded, late-1970s America, at a time when the economy was hurting and the nation’s pride had taken a few hits. The big push to impose metric under the Ford administration was met with resistance based in part on pragmatism (the taxpayer costs of switching; the general lack of enthusiasm in the populace) and in part on defiant nationalism. “There were those who considered metric conversion to be unpatriotic,” writes Marciano. No less a figure than the director of the National Cowboy Hall of Fame declared metric was “definitely communist.” Stewart Brand decried the “despicable attempts by government to put an entire people on one ‘convenient’ system.” Tom Wolfe accused elites of kowtowing to fashionable Europe, sneering that “we’re still the most obedient little colonials when it comes to things intellectual.” In the end, the anti-metricians won.

And the result was that we crashed a lander into Mars. But we also do other things to the beat of our own drummer. Red, right, returning in the US and Japan; green right returning elsewhere. Also in most places in the world except the United States, the rear brake on a bicycle is on your left hand, not on your right.
Tony
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