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A couple of newbie questions
On Sun, 18 Jan 2004 03:28:28 -0500, "Gary Warner"
wrote: "Joe Parsons" wrote: A nautical mile is also, precisely, 6,076.12 feet. [HAIRSPLITTING=ON] That's not precise--that's rounded to two decimals. A nautical mile is, by definition, precisely 1,852 meters, as mentioned above. That converts to 6,076.11549 feet (which still is not precise!). [HAIRSPLITTING=OFF] [HAIRSPLITTING = ON AGAIN] Actually, the statement, "A nautical mile is also, precisely, 6,076.12 feet." IS precise. It may not be exact, but it is precise. [HAIRSPLITTING = OFF] Spliting of hairs Actually, precision is how you define precision - it is a fairly flexible term. One can be precise to two places or ten places - it all depends on how the number is used. Thus, I choose to be precise to 3.88451 feet - 6,080 feet it is. ;) /Splitting of hairs Later, Tom S. Woodstock, CT ---------- "My rod and my reel - they comfort me." St. Pete, 12 Lb. Test |
A couple of newbie questions
also wrong, but what the hey it is simple and complete.
Where exactly is it wrong? among other things, there is no reason whatsoever that a boat MUST go over top of a wave rather then through it, and a sin function does NOT explode at zero degrees. |
A couple of newbie questions
gene, be stupid if that's what you want. who cares.
Obviously, since you are *so* much more intelligent that we are and we have nothing to contribute to your most important life, it would be best if you went back to where you were for the most of 2003... (away from here). Lest you forget that we are dirt under your feet and nothing but an irritant destined to spoil your cardiovascular health, please re-read: http://tinyurl.com/2uuuc Then go back...... Byeeeeeee..... -- Grady-White Gulfstream, out of Southport, NC. http://myworkshop.idleplay.net/cavern/ Homepage http://www.southharbourvillage.com/directions.asp Where Southport,NC is located. http://www.southharbourvillage.com/autoupdater.htm Real Time Pictures at My Marina http://www.thebayguide.com/rec.boats Rec.boats at Lee Yeaton's Bayguide http://www.cafeshops.com/recdotboats Shameless Commercial Plug for Lee's Rec.Boats Clothing |
A couple of newbie questions
The concepts being wrestled with here are "precision" and "accuracy".
Precision implies repeatable results to some number of decimal places plus or minus an uncertainty factor. Accuracy implies the correct answer in absolute terms. ================================================== === On Sun, 18 Jan 2004 11:37:42 GMT, Short Wave Sportfishing wrote: On Sun, 18 Jan 2004 03:28:28 -0500, "Gary Warner" wrote: "Joe Parsons" wrote: A nautical mile is also, precisely, 6,076.12 feet. [HAIRSPLITTING=ON] That's not precise--that's rounded to two decimals. A nautical mile is, by definition, precisely 1,852 meters, as mentioned above. That converts to 6,076.11549 feet (which still is not precise!). [HAIRSPLITTING=OFF] [HAIRSPLITTING = ON AGAIN] Actually, the statement, "A nautical mile is also, precisely, 6,076.12 feet." IS precise. It may not be exact, but it is precise. [HAIRSPLITTING = OFF] Spliting of hairs Actually, precision is how you define precision - it is a fairly flexible term. One can be precise to two places or ten places - it all depends on how the number is used. Thus, I choose to be precise to 3.88451 feet - 6,080 feet it is. ;) /Splitting of hairs Later, Tom S. Woodstock, CT ---------- "My rod and my reel - they comfort me." St. Pete, 12 Lb. Test |
A couple of newbie questions
On Sat, 17 Jan 2004 17:30:05 +0000, DSK wrote:
Lou Dempster wrote: Could someone please tell me what a knotical mile is in comparison to the standard mile. Also what does D/L limited speed: 10.08 kt. and Disp. Hull Speed: 5.90 kt. mean. I am just fooling around with a hull designer and would appreciate any info. Well, other have answered the nautical mile question, so I'll try the other two. Displacement hull speed is the highest speed a given hull can reach when limited to it's wave train. What this means is that the boat is fully supported by displacement of water (as opposed to planing, where the boat is supported by hydrodynamic force of water going by under the hull) and so therefore it has to push water out of the way, making waves. A less obvious point is that the water has to come back together again as the boat passes.... in traditional hull design, the key to designing a fast boat was always said to be to minimize the stern wave. Displacement hull speed is determined by waterline length. The further apart the bow & stern waves are, the faster the connected wave train can move across the surface. At 5.9 knots, the crests of the bow and stern wave are about 18' 4" apart, so I bet that is the waterline length of the hull you are designing. I'll agree that this is a great explanation of "hull speed" and will only add that it is theoretical. "Displacement" boats often exceed "hull speed" in certain conditions without planing. But hull speed is an excellent "mark" to do calculations with. If you're doing around hull speed with, say, a certain engine and prop combination, don't expect to go much faster if you you add more hp, etc. If you're nowhere near hull speed, doubling hp may close to double your speed. But as you approach hull speed, it takes more and more hp to go any faster. (For a sailboat, replace hp with "sail area, wind speed, etc.") Lloyd Sumpter "Far Cove" Catalina 36 - hull speed 7.5kn, has seen 10 |
A couple of newbie questions
On Sun, 18 Jan 2004 08:54:44 -0800, "Lloyd Sumpter"
wrote: "Far Cove" Catalina 36 - hull speed 7.5kn, has seen 10 ============================================= Lloyd, what is your water line length (LWL) ? |
A couple of newbie questions
and will only add
that it is theoretical it is not even theoretical. It is and always was just scientific sounding gibberish. |
A couple of newbie questions
"Wayne.B" wrote in message ... The concepts being wrestled with here are "precision" and "accuracy". Precision implies repeatable results to some number of decimal places plus or minus an uncertainty factor. Accuracy implies the correct answer in absolute terms. ================================================== === On Sun, 18 Jan 2004 11:37:42 GMT, Short Wave Sportfishing wrote: On Sun, 18 Jan 2004 03:28:28 -0500, "Gary Warner" wrote: "Joe Parsons" wrote: A nautical mile is also, precisely, 6,076.12 feet. [HAIRSPLITTING=ON] That's not precise--that's rounded to two decimals. A nautical mile is, by definition, precisely 1,852 meters, as mentioned above. That converts to 6,076.11549 feet (which still is not precise!). [HAIRSPLITTING=OFF] [HAIRSPLITTING = ON AGAIN] Actually, the statement, "A nautical mile is also, precisely, 6,076.12 feet." IS precise. It may not be exact, but it is precise. [HAIRSPLITTING = OFF] Spliting of hairs Actually, precision is how you define precision - it is a fairly flexible term. One can be precise to two places or ten places - it all depends on how the number is used. Thus, I choose to be precise to 3.88451 feet - 6,080 feet it is. ;) /Splitting of hairs Later, Tom S. Woodstock, CT ---------- "My rod and my reel - they comfort me." St. Pete, 12 Lb. Test Not exactly. Precision can be described to how many decimal places you go out. Accuracy is how good is the data. 3.88451 is a precision of 5 decimal places and an accuracy of 4 decimal places. The number can be from 3.884505 to 3.884514 And multiplying does not increase precision, only continues the precision of the input values. 3.21 x 3.21 != 10.3041 is only accurate to 10.30. The rest of the numbers are noise / garbage. |
A couple of newbie questions
3.21 x 3.21 != 10.3041 is only accurate to 10.30.
correct me if I am wrong, but as I remember it 3.21 x 3.21 is only accurate to one decimal because the factors are accurate to only 1 place. I am pretty sure of that but it has been a while since I worried about "precision" and "double precision" numbers. |
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