Base Plate Compass, "every" part identified and explained

foreign [Music] hello today I want to show you what all the various parts and features of a base plate Compass are and explain what they're for now the reason for this is this morning I went online and I couldn't find a website or a YouTube video that actually showed you what all the parts are and that includes the compass manufacturer's websites not one single website anywhere on the internet gives you details of what all the parts are on a base plate compass and considering that most people use base plate compasses um it was a bit surprising so anyway what I'm going to do first of all I'm going to go through how to use these ones which are standard base plate compasses and then I'll just explain what the extra features are on these ones which are just base plate compasses with a mirror attached I'll put these down first now all large manufacturers make base plate Composites but none of them actually tell you what all the bits are for how are you supposed to know when you want to buy a new Compass or replace the one you've got how are you supposed to compare the features online before you make a decision if nobody tells you um as an example let's have a look this Brunton Compass I don't know if you can see that that has small holes that run along the top edge of the Brunton Compass now these are epe holes but nobody explains what they're for EP holes by the way are if you take if you if you're using a GPS and your GPS tells you that you're a certain at a certain location you can place one of the holes on your map depending on which scale you're using they've got scales written on them and you will be somewhere in that hole so EP is just estimated position area estimated position error and it gives you a statistical level of confidence in in your GPS position that's all it does this sun toe Compass this one curves up at the back because they say it's more ergonomically pleasing which just means it feels nicer to hold but for today what I'm going to use is I'm going to use this which is just the standard silver Expedition 4 which is probably the most common compass non-military that you used when folk are out in the countryside I'm not on I just have to say I'm not on commission or I don't get payments off any Compass manufacturers or any anybody else in fact so this is just my personal opinion all these companies are my personal property so let's crack on and have a look at the base plate Compass so I suppose the first question would be why they called base plate compasses um it's a very simple answer to that is uh everything is either stamped into printed on or attached to this clear acrylic plastic plate and that acts as the base for the rest of the features on the compass so that's why it's called the base plate Compass so the first item would be the direction arrow which is this feature here this is stamped onto the compass on the base of it and what that does is once you've taken a bearing that is the direction that you would follow you would go in that direction or if you're taking a bearing from something say the corner of a wall or I don't know the top of a mountain then you would that you would point the arrow at whatever it is you're taking your bearing from and then take your bearing that way so that's the direction arrow the next feature is this which is this small Mark here this is a luminous pointer so it glows in the dark and all that does is it takes the place of the direction arrow if you're using the compass in the dark so you'll be able to see that and if you're walking on a bearing you just point that along the bearing and that's the direction that you travel the next feature are these three right angle Marks here with um numbers written along these are Roma scales and they're used to take measurements from a map or you can use them to take UTM coordinates or grid references I've made a video on how to do that so I'll place the uh the link to that in the description box so let's have a look at how you use Aroma scales so this is a one to twenty five thousand map and as you can see there is a one to twenty five thousand Roma scale so if you wanted to know how far it was from this wall corner here to the wall Junction there all you do place your compass place the Roma scale along the wall from here to here and then read the numbers on the compass and as you can see shows this wall is 425 meters from The Junction to the corner and last but not least with Aroma scales you can also use any of these Roma scales for taking very accurate UTM coordinates on a map or grid references if you're in the UK there's a video that I've made on how to do this again I'll put the link in the description box the next thing to look at is the rotating dial or the bezel this particular one has degrees marked around the edge some of them have NATO Mills they tend to be more for military use the way this works is you say you want to set a particular bearing let's say we want to set the bearing of 330 we rotate the dial until it's 330 at the top and then if we wanted to follow that bearing we set off in the direction indicated by the direction arrow so that's what that is the next thing to notice are the orienting lines which are the straight lines inside the compass inside the dial or the bezel what these do is these allow you to orient your compass to your map let's say you're at this particular wall Junction let's find one there's a wall Junction and you want to walk on a bearing of 130 degrees all you do is put the line the black line that runs in the center of the uh the base plate put it onto the wall Junction which is there and then simply keeping it in so it's touching the wall Junction rotate the rotate the entire Compass until the orienting lines are pointing straight up the map so they're pointing straight North so if you wanted to walk on a bearing of 130 degrees you would go in that direction indicated by the direction arrow so that would be your direction and that's what the orienting lines are used for so the next item in hour clockwise rotation of the compass is this this is a ruler an imperial ruler so it's done in inches and you could use that for measuring distances on a map one two one inch to a mile so that's what this is the next item is this thing in the middle here this is the magnetic needle um if it it's it rotates around a frictionless and almost frictionless bearing which is here and it points to magnetic north I know before anybody starts giving comments it technically it follows a horizontal magnetic flux lines but let's just say it points to the Magnetic North Pole it'll keep things simple for the needle to rotate as you can see like that it the base plate needs to be kept reasonably level if it's like this it's it's not going to rotate correctly so for the to allow the needle to rotate keep the base plate quite quite level the next item doesn't really have any effect on the operation of the compass in most cases which are these this little circular these little circular points there what they are their risers and if you look at the base of the compass they're small rubberized silicon um spots what they do is they allow you to when you put the compass onto a map they stop it sliding around and they also stop the base of the compass being scratched if you do move it around on something that's not uh soft they stop the compass becoming scratched so that's risers another item which doesn't really affect the operation of the compass is this this is the lanyard attaching point it just it's just a a strong point on the compass that you can attach a lanyard to it's always a good idea to keep your compass attached to either a pocket or to your rucksack so you don't lose them because they are they're quite expensive so this is the lanyard attaching point this Arrow inside the bezel or the the dial is called the orienting arrow which is there so if you it's used to set your compass once once you've taken a a bearing let's say you want to take walk on a bearing of due south all you would do is rotate the entire base plate until the arrow is directly underneath the magnetic needle and that's what the orienting Arrow does if you want to take a battery want to follow a bearing of 120 you would rotate the entire base plate until the arrow is directly under the needle again and you would then follow the direction arrow along this side of the compass here we have another ruler remember we've got this ruler down here which is Imperial this is a metric ruler marked in centimeters and it can be used to measure distance on any metric map so that's what this is inside the dials you can see these num numbers printed in red in this case on this particular compass and at the end it says e declination and W declination these are your fixed declination scales um most people don't use them but if you want to the way it works is let's say that you take a bearing and you want to walk in I don't know let's say you want to walk Due West so all you do and let me zoom out a little bit oops on the wrong way so I've zoomed out so I want to go Due West so all I do is rotate the entire base plate and let's say that my the area that I live in I have a declination of 20 degrees east all I do before I do anything else is I rotate the entire base plate until the magnetic needle is pointing at the East 20 Mark there and I then rotate the arrow underneath and then my declination is set for that particular time um honestly then it's a there are a lot easier ways to deal with Magnetic explanation I've I've made a video magnetic declination simplified again I'll put that in the description box I'll link to that the next part is this little line here a small line that you can see as you rotate the dial so I'm there can you see the small line that doesn't move that is an extension of the direction arrow so you go it's got a luminous base so it illuminates at night and then you would you could use that with the Luminous pointer it also marks the uh the place on the dial where the bearing is red so if you were taking a bearing of 290 you would set it to there so the index line is directly under the 280. so that's the index line the next thing you can see on this particular base plate is this circular hole with four crosshairs some compasses have triangles some have squares but they all have the same use I'll show you how they work let's say that you wanted to have draw a circle around a very specific point on your map let's say this wall Junction here all you do is you place the circle over the wall Junction and then you use a crosshairs to ensure that the wall Junction is directly in the center of your circle and then you take your pencil or a marker and draw a circle around it these these lines that you can see drawn onto the base plate which is here and here these are called well on the compass manufacturers websites they just call them a line they're actually Parallax lines a parallax is just you would get a different view of something depending on which angle you're looking at it and because the Parallax lines are actually stamped onto the the base of the compass wherever whichever direction you look at this line it's always touching whatever it is on the map so say you wanted to go from this point here to this point here you would Place The Parallax line directly onto it and then you know that that's the uh it's it's actually you haven't got any Parallax errors and from there you could simply take a bearing and that would give you a very exact bearing if this line isn't actually long enough on this particular Compass you can use the line that starts here and continues here it also continues up to one to forty thousand Roma and then for some reason it also lines up directly with the number three so you can actually sorry number three on the one to twenty five thousand Roma so you can actually use the entire compass as a parallax line this point here this circular feature here is a magnifying glass or a magnifier Maps contain lots of very small pieces of information they spend a lot of time drawing these maps you can only cram so much information onto a piece of paper so they tend to be printed quite small sometimes so having a magnifying glass actually helps you read it this small circular depression and the top left of the base plate on this particular compass on other compasses it will be in different location but this is the label holder some specialized compasses such as scientific compasses and Military compasses instead of having luminous pointers they'll actually have a decaying isotope such as tritium which will actually make certain parts of the compass glow so they're a lot they're a lot easier to use at night the label holder would simply have a little radioactive sticker I haven't got I'm sure you can get one on Google somewhere so that's what this little circular depression is so that's all the features and the parts of standard base plate Compass the only other thing that all manufacturers will add to a base plate are these they're they're mirrors they make them into mirror compasses these are particularly useful if you want to take a bearing from something that's a long way away say two miles to the top of a hill somewhere or you can see a building off way off in the distance and you want to take a reasonably precise bearing you can use a mirror Compass or anything it'll help you do that again all the compass manufacturers build in different things into their mirror compasses that they think that their customers will want let's have a look and see at some examples as an example this Brunton Compass as you can see there they've built in there there's a spirit level so when you take a a site from something something you can actually check that the uh the compass is being held level um the sun tower Compass which is this one here they've put a notch an illuminated line leading to the notch on the top of the mirror and that will assist you if you're using the mirror Compass at night they've also if you look on the side here they've built in a scale on both sides and they're at different map scales so you've got one to forty thousand one two sixty sixty two and a half thousand and one to fifty thousand what these lines do is you can place them on contour lines and it will give you the slope gradient it'll tell you how steep that particular piece of slope is just by looking at a map but once again I'm going to use a silver Compass um just because it has more features than other compasses of this type I'm not including things like the Brunton true art 20 which has lots of features but they tend to be very specialized so they use more by geologists and what have you I'm more interested in people who go walking and trekking over the mountains so let's have a look at the mirror itself and see what the features of the mirror are the first thing you'll notice is at the bottom of the mirror is a hole all compasses all mirror compasses have this hole you can see it there it's on the inside now what that's for is if you're looking up a slope and you want to know the angle point the compass up the slope like this you would look through the hole up the slope and then you can read the slope angle on this bit I've made another video I think it's called slope angle with or without an inclinometer so if you have a look at that that gives you a lot more detail about that particular little hole at the bottom mirror I'll put a link again there's going to be a lot of links I'll put a link again in the description box the obvious thing here is the sighting mirror this thing here what this does is this allows you simply to look at an object say I want to take a bearing off a tree over there I would fold the mirror over I would then line the notch at the top of the mirror here up with whatever it is I'm going to take a bearing off and then rotate the compass at the same time I'll show you in a bit a little bit more detail let me zoom in so let's say I want to take a bearing off the center of those the center tree of those three trees all I will do is hold my mirror up in front of me open it until it's 45 degrees and then point the Notch and the the line that runs up the center of the dial and then I then rotate the dial until let me get it let's get it reasonably exact until the needle is over the arrow it's not is it it will be in a minute there you go that's it and then all I do open my compass and simply follow in that direction and that will give me take me to the center of those trees inside the sighting mirror there are sighting lines which is what you would actually look up and then through the notch at so the sighting line the vertical sighting line you would a line up with something and then you would take a bearing the next thing on good quality compasses you also have a horizontal line and what that's for is I just happen to have one of these because I always take one of these up a hill what they do is if you hold the compass at 45 degrees so there it is at 45 degrees and then you then look this way the cross of the horizontal and the vertical sighting line should be directly inside in the middle of the magnetic needle let me zoom in and I'll show you I'll demonstrate so here are the lines this is the horizontal line here on the on the mirror and this is the vertical line so if you close the mirror until the cross made by the horizontal and vertical lines is directly over the center of the magnetic needle that will give you the ideal position to take a bearing one thing to bear in mind between there is another difference between a base plate compass and those with a mirror attack on a standard base plate Compass the index line is here this is the point well zoom in this is the point here this line is the point at which the bearing is red on a mirror Compass it's different because you know the mirror takes up some uh space on the compass so in this case the index line is there this small luminous pointer there so as you rotate the dial set your bearing and then you would look just below the index line which is this point here and then you would read your bearing at that point okay so that's everything there is to know about the parts of the compass it's not an instruction video on how to actually use all the various parts that would take um I don't know 500 videos but at least now there actually is a YouTube video that tells you what all the parts of a base plate Compass is or are the only thing I haven't covered is things like the declination adjustment screws the inclinometer and stuff like that because they're not actually on all compasses thanks for watching

Channel: The Map Reading Company

Views: 463,151

Keywords:

Id: LVf0v0TqoOg

Length: 22min 1sec (1321 seconds)

Published: Mon Apr 17 2023