Model Boat Mayhem
Technical, Techniques, Hints, and Tips => Other Technical Questions... => Topic started by: justboatonic on May 16, 2008, 09:49:22 pm
-
..........a nautical mile and a (landlubbers) mile? :embarrassed:
-
Look it up! http://science.howstuffworks.com/question79.htm
-
Hmmmmmmmmmmmm, thanks but I thought this was the part of the forum to ask questions ???
-
Look it up! http://science.howstuffworks.com/question79.htm
I am sure that that exclamation mark got in there by accident....
-
One landlubbers mile = 1.150782 wetmiles O0
-
..........a nautical mile and a (landlubbers) mile? :embarrassed:
One's wet and the other one is dry!! ::)
-
O0
140 grit is wet and dry
:D
-
Hmmmmmmmmmmmm, thanks but I thought this was the part of the forum to ask questions
And to encourage research. :)
-
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.
-
O0
140 grit is wet and dry
:D
So is my G&T - in that order, too - but I have a cunning plan................. ::)
FLJ
-
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
-
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 %%
-
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.
-
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
-
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
-
Fuel economy is expressed in gals/hour, or tonnes/day
Ian
-
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!
-
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.
-
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 :-)) :-))
-
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.... %%
-
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.
-
How do you clean the hull? Surely not by drydocking that frequently? Presumably the hull is also coated with antifouling?
-
Come on Colin , have you not seen that advert for mouthwash {-) {-) .
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.
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 :-))
-
The Engine Room will always make port first because the Deck Gang are always slow off the mark..... %)
-
Cleaning is done with divers who operate a pair of very large rotating brushes. The brushes are drawn into the hull by water pressure and the rotation creates forwards movement as well. The diver simply hangs on to the device by the steering wheel and controls its progress acros the hull. The whole thing is driven hydraulically via a diesel engine driven hydraulic pump on the quayside with all the hoses bound together in an umbilical cord. The detail is finished off with much smaller rotating brush units.
The paint nowadays is more like a fibre glass resin and is a long way from the old anti-fouling paints that are now so unpopular with the environmentalists. This stuff is sprayed on and is basically there for life, forming a resin coating, but of course not being anti-fouling it does need regular cleaning, especially if the vessel does not do regular high speed runs and operates in very warm waters. Just like us!!
-
The Engine Room will always make port first because the Deck Gang are always slow off the mark..... %)
Try telling that to a dip dab :}
Deck germs recon that us engineers are just unwanted ballast %% that is untill thers no light, water or some work to be done ! {-) {-) {-)
:} time to hide O0
-
anti-fouling paints that are now so unpopular with the environmentalists
Ii didn't know that, what the problem with anti-fouling?
By the way...... how do anti-fouling paints work?
-
'Traditional' anti-fouling as used until fairly recently contained substances which killed the molluscs and weed which wanted to adhere to the hull. The problem was that these same substances leached into the seawater and thence into the food chain and onwards into us. :(( Dry-docks shotblasting or HP waterwashing the hulls of vessels painted with the now banned compounds have to make special arrangements to dispose of the old coatings. Coatings nowadays have to be chemically inert and (I think) most seem to rely on a smooth finish to which the barnacles etc. cannot adhere. Some are self-polishing which become smoother in service but these are only effective on vessels making regular fast passages (no use on tourist barges). %)
I recall operations with a vessel which was used as a testbed by a paint company which painted test squares of differing antifouling on the underwater hull. After a few months in service, the difference in performance of the coatings was obvious.
Thus, for all those hobby sailors still using that old tin of anti-fouling you found at the back of the shed, be aware that you can now be suspended by the schronicles if detected.
Barry M
-
Modern yacht anti foulings are still copper based but no longer contain the toxic chemicals they used to. They still work by leaching and exposing copper which kills marine life which is why you are not permitted to fish in Marinas.
-
See http://www.ukmarinesac.org.uk/activities/recreation/r03_03.htm
BM
-
Hi Bryan Young. If I remember correctly the Statute mile was 'established' at 5280 feet because the mile had been a bit variable around 5000 feet before that. I suggest that it was a knowledgable bloke who said lets get this right for everybody and told the Law makers what to do.
I would take issue with the words knowledgable and Politician occurring in the same sentence though.
Regards Roy
-
I'm pretty sure that this thread was started off as a light-hearted query. It's getting too serious now. Bunkerbarge is absolutely correct in what he says, but given the amount of modern technology at his grease filled fingertips I'm not surprised that "slip" can be more accurately measured than in days of yore. So, while agreeing with him, my rather obsolete reasoning remains (sort of) correct. As far as the engineers getting off on shore-leave first: this comment does have a precedent. We were tying up in Belfast at about 2am during a rotten night and we were having an awful job getting the bow ramp positioned....when a very junior engineer just barged into the wheelhouse demanding of the Captain "What time is shore leave, skipper?". As you can imagine, this did not go down very well and has remained in my memory bank ever since.
I have always enjoyed the banter between us "fish-heads" and the "clankies"....long may it exist, and as long as the banter stays at banter then it can be enjoyed by everyone. We all have (had) our own skills which came together to make a busy ship a complete working entity. No department could succeed in isolation...and that's what makes a ship work. End of story. BY.
-
Here Here :-)) BY
Ps I wish you had sailed on some of the ships I have had the missfortune to be on with oil and water mentality. at least the last few have been acomplete team venture enjoying the banter that was thrown around dip babs dirt birds deck germs grease monkeys and spare ballast to name the polite ones LOL
I try not to worry over things like prop slip fuel ecconnomy just whether I will live another day {:-{ well you never know when cookie will kill you with his mix of chockfast and soup....
R, and yes I'll take the monkeys fist ashore for you if you want.
-
I totaly agree with Catengine man Take a deckie and put him in the engine room and he will scratch his stern and wander off muttering about noisy smelly things,but put an engineer on deck and and we can do most things a deckie can :D :embarrassed:
-
:} :-))
R,
-
Now if we want to separate the Sailors from the boys send to the top of the main mast on something like The Victory or the Cutty in a storm. ;D And to paraphrase a great movie line "ENGINEERS, ENGINEERS - WE DON'T NEED NO STINKING ENGINEERS" ;) we got SAILS. :-)) :-)) :-))
Andre
over yonder in Portland Oregon
-
" I totaly agree with Catengine man Take a deckie and put him in the engine room and he will scratch his stern and wander off muttering about noisy smelly things,but put an engineer on deck and and we can do most things a deckie can"
Now if we want to separate the Sailors from the boys send to the top of the main mast on something like The Victory or the Cutty in a storm. ;D And to paraphrase a great movie line "ENGINEERS, ENGINEERS - WE DON'T NEED NO STINKING ENGINEERS" ;) we got SAILS. :-)) :-)) :-))
Andre
over yonder in Portland Oregon
PS Martin could you delete the other message "Reply #36"
-
amdaylight
The Victory was one of the few sailing ships that did actually carry an ENGINEER.
His job was to look after the bellows bilge pump!!!
Bob
-
Whatever the digs Deck, Engine and even Sparks and the Chief Steward might have at each other, those of us who have served at sea in a professional capacity are well aware that we all relied upon each other to get safely from A to B.
As Bryan said "We all have (had) our own skills which came together to make a busy ship a complete working entity. No department could succeed in isolation...and that's what makes a ship work."
Nuff said before this thread descends into peurile Yah-boo name calling.
Barry M
-
True now-days there is (with hope in my heart) no more of the *oil and water mentality* that was rife when I first set sail (went to work on vessels) some 33 years ago.
I am now with a great crew on a good ship and we ALL can have a laugh, true they call me gadget man and add that "all will be ok as *Bert* will fix it."
I have sailed with crew where the [deck officers] have slammed the bridge door in my face because I was only an engineer and they did not have engineers in the wheel house
I have learnt to live together alongside any seaman/woman I have even served under a female chief Eng to which I found most pleasing as she replaced a total (donkey).
There was (probably still is) a saying that you should never upset the cook on a ship the truth is you should try to never up set anyone as that makes our short life on this planet more enjoyable.
I am not saying I never get ####ed off with anyone and I know I probably annoy a few within the crew but we ALL work round it and the ship runs smoothly.
And IF my skipper comes on here to contradict me then thats up to him, but he has to remember WHO fixes his models {-) {-)
R,
-
To be really honest about all this lot is one bunch of people that (with notable exceptions) were the RN Officers of an embarked Flight. Insular, arrogant and a total belief that they were gods csen ones and we were just there to ferry them around and do thier bidding. They couldn't see that we were all skilled individuals and that they all came out of the same (Dartmouth) mould. Very few free thinkers among them.
-
I've seen good engineers and I've seen bad engineers, I've seen good deck officers and I've seen bad deck officers, it is all down to the individual at the end of the day.
I have all the respect in the world for a deck officer who can appreciate the requiremnt of wind and tides, plan his passage accordingly, get us there safely using as little fuel as possible and manoeuvre us in and out of port competently and skillfully. Sadly there are very few of them left as most simply watch the automation and stick to a certain speed or, even worse, certain revs. Exactly the same applies to many engineers nowaday who do not venture outside the control room enough and don't get a feel for thier machinery like I used to and rely on the automation rather than thier own senses to tell them when something is going wrong.
Also it may interest you to know that my father was a deck officer and he taught me that you can turn your hand to anything if you have the right attitude.
There again I always maintained he failed the entrance exam for engineering ;)