Psycho Warren

iTrader: (5)

what software package was that??
youve missed my point, of course you can just judge it in your head by guesswork from past experience, but combined with the speed distance calculations you can calculate the closing speeds, time and hence distance you will have to overtake and then check it with your judgement to see if its big enough.

And obviously you NEED to know the figures in your head otherwise you wont do the maths before you get home

remember though in the last few years of my career, it was by "bread and butter" job to be doing speed distance calculations, sohcahtah and pythagorus in my head while still looking out the periscope. So no calculator, and nothing to write on. You have to do it there and then so learning the numbers in your head so you dont have to think is essential. You could have 7 or 8 targets your looking at and you need to keep track of them all including knowing information such as:
Bearing,
Range,
Angle of the bow (what angle they point at you)
Height of main mast (to use in calculations)
approx speed
Distance off track (roughly how close they will come)
Look interval (how long until you have to dive from periscope depth if they turn towards you and try to run you over)

and on top of that you need to be able to use the maths and figures to calculate closest point of approach, time of the attack (ie how long it takes for torpedo to get there), time to intercept, time to CPA etc etc.

All that while still maintaining a look out on the periscope....

So yes IMO it is reasonable to use such calculations to get exact overtaking data. Although i wouldnt advise it unless your mental maths is very good and your well practised.

Its also a good "bollocks" check to ensure your judgement is sound when the maths proves it right.

Obviously if your maths is shit then dont try it

Although interestingly i taught it to an autistic teenager to help him judge distances when driving and to help him make decisions and he has now passed his driving test and drives round perfectly safely! So not useless at all.

155lee

iTrader: (10)

that must be the only maths calculation that if you get wrong the answer = death!

saph in dorset

it was catia V5 which is made by dassault (spelling) i use this at work when designing aircrafts and is an excellent piece of software.

Rob_DOHC

iTrader: (4)

Thats ridiculous mate,

stamp and hope seems to work faster and better. what equation do you use to factor in lag?

**EDIT**

just read this

My brother was a navigator on subs and had to do this too,

But still,

Rob_DOHC

iTrader: (4)

How does it compare with solid works? i've been using alibre for the last few days and its pretty good too.

Rob,

cjwood555

Catia offers better FEA facilities and is designed for large, complex assemblies. It's quite complex for doing a basic 5/10 part assembly due to the hierachical structure.

Rob_DOHC

iTrader: (4)

cool just did a google looks good, very similar to solid works, being as they are both made by dassult its not really that surprising!

Mark V8

iTrader: (2)

If you dont like Trig or Pythagoras try this .....

FREE SolidWorks 2D drawing software

http://www.3ds.com/products/draftsight/

I use it at work for quick 2D stuff rather than use SolidWorks.

Mark

Psycho Warren

iTrader: (5)

i dont need to factor in lag because from experience i know i can accelerate to 60mph from 40 by the time im alongside the vehicle im overtaking so the calculations are based on the vehicle in front from a distance perspective. makes the maths easier as then im using a simple 60mph to calculate which is much easier as 6's are dead easy with time being measured in 6's too.

id agree its rediculous for the average guy but with practice you can use it to affect quite well especially on roads where you know how long the straights are so can easily work out the times involved. means you can be clear and past confidently while most people would be still thinking about it. you do have to think at least 1 corner ahead though.

cool! Id just taken over as navs when i fell ill. Done it before on my previous boat though.

he still serving??
in a worst case scenario yes. but thats why you do the calculations again and again and again so your confident enough to get it right. plus the "control room team" are supposed to do a bollocks check as you give your answer to highlight any discrepancy so an error should be picked up.

its a high pressure environment when things go tits up, but then you get paid alot for a reason.

all the periscope drills are aimed at making you a good commanding officer as during your training you are subjected to all the worst case scenarios in simulations and exercises where you have to resolve the situation or you fail. After all you want a CO who doesnt kill his crew!!

it all stems from the good old days in WWII when you had no combat computers, and had unguided torpedos, so you had to do all the calculations in your head and had to get it spot on or the torpedo would miss the target ship. Think back in world war 2 you could have been firing at a ship from well over a mile away using pure mental maths.

you only had a rough estimate of the ships speed and a distance calculated from an estimate of its hieght. the rest you did in your head. you have to take into account both the time it takes your torpedo to travel to the target and the distance the target will move in that torpedo travel time, so that you can fire the torpedo ahead of the ship at the right angle to get a direct hit.

even then it wasnt an exact science so often you had to fire a spread of torpedos.

also remember if the ship detects you they will alter course fucking up your maths for a minute or so. Ironically though a course change is good for calculating their exact distance. if they move course while torpedos are in travel then you could miss.

in the modern world its not so much about sinking nazis or commies anymore but about ship safety as a large ship would cause a lot of damage if it hits a submarine at periscope depth.

you start training to do periscope drills before you ever get near a real submarine. As a very junior officer you are trusted with a lot of responsibility albeit you dont make the big decisions you just call for help if a ship looks dodgy and as you get to navs and watch leader in effect you make all the main decisions by veto (ie the captain is told and only stops you if its wrong) and are trusted to get it right.

even in peacetime you can as in my job as navs be on the periscope managing 7 or 8 medium to close ships and doing all the maths to keep the submarine safe. takes a lot of practice but is very satisfying. BUT thats only ONE part of your job!! Youll be also giving conning orders to steer the submarine and following a navigation plan and doing the chart work when your oppo has taken over the periscope for you. Plus of course you have other roles in emergencys on top of that and in the worst case you could be doing the whole periscope work while wearing breathing apparatus due to a fire fucking hardwork to stop steaming up and the sweat streaming into your eye stinging like fuck yet you cant rub eye due to face mask yet need to be able to see to look out periscope and keep the boat safe!!!

fun though.

155lee

iTrader: (10)

fuck,so if you get the maths wrong you die,and if you get other maths wrong the enemy doesnt die.
that sounds pretty heavy,i do calculations for pressure at depth,deviated oil wells,different weights of fluids and i found that hard and thats without any guesswork.

Psycho Warren

iTrader: (5)

yep thats the potential consequences if you get it wrong. if your luckly you just hit a sandbank then look like an idiot on national TV as the boat is beached!

madmikeiii

Why not just draw it out on paper then use a ruler to measure it and a protractor for the angles .
Mind if you know the math its better.

Mike

madmikeiii

Have you played a video game lately, all them cars/planes/images are made up of polygons, know I bit off base but !!!!!!!!!!!!!!!!!!!

madmikeiii

that would be nearly 4 minutes of a degree then, or a nano second of a degree course in mathematics or such like lol.

Mike