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Author Topic: What's the difference between................  (Read 5434 times)

justboatonic

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What's the difference between................
« on: May 16, 2008, 09:49:22 PM »

..........a nautical mile and a (landlubbers) mile?  :embarrassed:
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Colin Bishop

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justboatonic

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Re: What's the difference between................
« Reply #2 on: May 16, 2008, 11:27:17 PM »

Hmmmmmmmmmmmm, thanks but I thought this was the part of the forum to ask questions  ???
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banjo

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Re: What's the difference between................
« Reply #3 on: May 16, 2008, 11:34:00 PM »

Look it up! http://science.howstuffworks.com/question79.htm

I am sure that that exclamation mark got in there by accident....
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sheerline

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Re: What's the difference between................
« Reply #4 on: May 16, 2008, 11:40:47 PM »

One landlubbers mile = 1.150782 wetmiles O0
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Bunkerbarge

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Re: What's the difference between................
« Reply #5 on: May 17, 2008, 12:08:18 AM »

..........a nautical mile and a (landlubbers) mile?  :embarrassed:

One's wet and the other one is dry!! ::)
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banjo

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Re: What's the difference between................
« Reply #6 on: May 17, 2008, 12:09:41 AM »

 O0
140 grit is wet and dry

 :D
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Colin Bishop

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Re: What's the difference between................
« Reply #7 on: May 17, 2008, 09:51:44 AM »

Quote
Hmmmmmmmmmmmm, thanks but I thought this was the part of the forum to ask questions   

And to encourage research. :)
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Bryan Young

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Re: What's the difference between................
« Reply #8 on: May 17, 2008, 03:44:17 PM »

A more "serious" answer would be that a land mile is a "statute mile" meaning its length was decreed by knowledgeable politicians and enshrined in law (hence "statute"), and measures 5,280 ft. A "Geographical" mile (bet you didn't know that one even existed!) is a length of the equator equal to 1 minute of arc and is 6,o87.2 ft. (this is the measurement that defines time). The Nautical mile is the length of 1 minute of arc on a meridian. If the earth was a sphere then the nautical mile would be the same as a geographical mile. But it aint. So if a nautical mile was measured at the N.Pole it would be 6,107.8ft, while at the equator it is 6,046.4ft. So it was averaged out at 6080 ft as a standard. Too much information? Sorry. But the question was asked!. BY.
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FullLeatherJacket

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Re: What's the difference between................
« Reply #9 on: May 17, 2008, 03:53:58 PM »

O0
140 grit is wet and dry

 :D

So is my G&T - in that order, too - but I have a cunning plan................. ::)

FLJ
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sheerline

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Re: What's the difference between................
« Reply #10 on: May 18, 2008, 09:22:51 AM »

Very thorough Bryan, amid all the frivolity and fun we have on here, it's answers like that which make Mayhem the best site going. Looking into some of the other sites, this one always comes up trumps! O0
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Hagar

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Re: What's the difference between................
« Reply #11 on: December 01, 2008, 11:45:36 AM »

He is a link to a site that I find quite usefull.
http://www.convertworld.com/en/

it is also possible to change the language to your prefered tonge

This tells me that 1mile = 0.87 sea miles or 880 fathoms or 1.7x10to the power of 13 lightyears   %%



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BobF

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Re: What's the difference between................
« Reply #12 on: December 01, 2008, 11:53:59 AM »

Serious question, from some one who should already know the answer but does not.
Is that why a speed at sea is not measured in MPH? as the sea mile is longer.
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amdaylight

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Re: What's the difference between................
« Reply #13 on: December 01, 2008, 02:56:24 PM »

Serious question, from some one who should already know the answer but does not.
Is that why a speed at sea is not measured in MPH? as the sea mile is longer.

Yes that is the reason.

Andre
over yonder in Portland Oregon
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portside II

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Re: What's the difference between................
« Reply #14 on: December 01, 2008, 02:59:20 PM »

Thats probably right Bob , but heres one for you techy's  how do you work out fuel economy on the sea due to the flow of the tides and would the nortical mile be longer or shorter??.
daz
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boatmadman

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Re: What's the difference between................
« Reply #15 on: December 01, 2008, 06:12:32 PM »

Fuel economy is expressed in gals/hour, or tonnes/day

Ian
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Bryan Young

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Re: What's the difference between................
« Reply #16 on: December 01, 2008, 06:50:39 PM »

Serious question, from some one who should already know the answer but does not.
Is that why a speed at sea is not measured in MPH? as the sea mile is longer.
No it isn,t. A "mile" to you is an arbitrary thing decided by politicians. A "nautical mile" is based on a lot of things that are geographically based. Something else to blame the politicians for!
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Notes from a simple seaman

Bryan Young

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Re: What's the difference between................
« Reply #17 on: December 01, 2008, 07:02:20 PM »

Thats probably right Bob , but heres one for you techy's  how do you work out fuel economy on the sea due to the flow of the tides and would the nortical mile be longer or shorter??.
daz
The Engine Room always gets to port before the rest of the ship. And the engineers are always the first off on shoreleave...whether or not the ship has actually arrived at its destination. The main problem is deciding on how much "slip" the props have. Bunkerbarge is the expert here but although they (the engineering staff) can "guess" at the slip, they can only compute it via the ships actual progress over the land (in this case; the sea bed). So if the ship has travelled "x" miles and the engine room has travelled "y" miles and the navigation staff can say with some certainty that such and such tidal stream has had an effect then a %slip can be arrived at. Tidal streams really only affect a ship when close inshore but ocean currents do have an effect although generally too minor to worry about. Clear now? BY.
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Notes from a simple seaman

boat captain

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Re: What's the difference between................
« Reply #18 on: December 01, 2008, 07:39:28 PM »

Talking about nautical miles and fuel consumption.  When on builders sea trials, all vessels go on a measured nautical mile.  This actually consists of several runs consisting of a 2 mile run up to the measured mile, the run on the mile, and a 2 mile run plus turning distance to start another run.  The idea of doing several runs is to take into account wind speeds, and current flows.

After each pair of runs at different shaft speeds or variable pitch propeller settings are completed, the calculations are averaged, giving you shaft horsepower, fuel consuption and knots at known shaft speeds or pitch settings and whether or not the vessel reaches her design specification.

There are various measured mile runs around the coast we used the Isle of Arran mile mostly due to it having very deep water, thus giving more accurate readings.

I hope this is of interest to everybody.

Joe   :-)) :-))
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ivorthediver

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Re: What's the difference between................
« Reply #19 on: December 01, 2008, 08:00:50 PM »

Sorry to eavesdrop on the conversation ..But I totally agree with "Sheerline" [answer 10] as apart from the Knowledge gained from this site ..of which there is shed loads for people like me....... I love the banter....... but I pay a heavy price for it ......as a type 1 diabetic
people who know me well get nervous when i laugh out loud ...whilst reading some of the comments.....and start shoveling digestive biscuits in the corner of my mouth.... in case i am having..."a funny turn".

so once they have left me in piece I have to have another injection to offset the biscuits forced down my throat....   %%
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Bunkerbarge

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Re: What's the difference between................
« Reply #20 on: December 01, 2008, 08:52:13 PM »

I'm afraid Bryan you are a bit off the mark with your slip description.

Traditionally slip was calculated by using the actual distance travelled through the water, measured by the speed log, against what you should have theoretically travelled and basically a screw design a propeller can determine how far you should have gone by multiplying the pitch by the total number of revs in a given time.  Nowadays we use an electronic speed log but do the same thing with the reading.  After each passage I get an actual through the water figure off the bridge and compare it with the total number of revs we have turned during the passage.

Using a simple calculation that involves correcting the pitch in metres to a reading in nautical miles all the engineers are interested in is how far we have actually travelled through the water against how far we should have.  The difference generates the slip figure as a percentage and is used to determine such things as the condition of the hull and when to clean it.  Typically when we have a dirty hull we can be looking at 22-23% slip but when it has just been cleaned we would be talking of maybe 18-19%. 

It doesn't sound a lot but it makes a big difference to fuel consumption and we look at cleaning the hull approximately every two months.
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Colin Bishop

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Re: What's the difference between................
« Reply #21 on: December 01, 2008, 09:15:41 PM »

How do you clean the hull? Surely not by drydocking that frequently? Presumably the hull is also coated with antifouling?
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portside II

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Re: What's the difference between................
« Reply #22 on: December 01, 2008, 10:13:29 PM »

Come on Colin , have you not seen that advert for mouthwash  {-)  {-) .
daz
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catengineman

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Re: What's the difference between................
« Reply #23 on: December 01, 2008, 10:54:11 PM »

The Engine Room always gets to port before the rest of the ship. And the engineers are always the first off on shoreleave...whether or not the ship has actually arrived at its destination.




OUCH! :}

sowhat have you got against us dirt birds?

but hey ho why worry as to what is what when there is beer in the nearest pubs tap  :-))
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BarryM

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Re: What's the difference between................
« Reply #24 on: December 01, 2008, 11:16:55 PM »

The Engine Room will always make port first because the Deck Gang are always slow off the mark..... %)
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