View Full Version : Transit Compass
I'd just like to say a big thank you to pteron (http://www.bushcraftuk.com/forum/member.php?u=206) and sargey (http://www.bushcraftuk.com/forum/member.php?u=96) for the Astro Navigation workshop (http://www.bushcraftuk.com/forum/showthread.php?p=711483#post71 1483) they ran at the Moot, it was very useful.
One thing that came out of it for me was the use of certain compasses that could also be used to measure altitude.
One very nice tool for this we were shown was the Brunton pocket transit (http://www.brunton.com/product.php?id=146) which is far beyond my budget unfortunately. A little poking around brought to light a new Composite version (http://www.brunton.com/product.php?id=66) which is considerably cheaper (and lighter too) but alas, still a bit rich for my blood.
Anyway, I was looking for something completely unrelated on Dealextreme when up pops this wee beastie (http://www.dealextreme.com/details.dx/sku.37796).
2980
It appears to be a Chinese knock off of the Brunton with a price of around £26.... It's got to be worth a try at that price I reckon.
So my order is in and I'll let you know my impressions when it arrives.
would I be right in thinking when you say altitude you mean estiamting your height relative to a know feature? If so any compass with a clinometre can be used - to a great orr lesser accuracy, such as the Silva type 15
or Suunto MC2
This link has some good brieft descriptions:
http://www.zoom-one.com/distance.htm
Gailainne
08-08-2010, 17:56
You beauty, like you I've been looking around for a light weight or pocket version to play with, even the Davis Mk3 sextant, £50 tho :(. Looking forward to hearing how you get along with it. Interestingly it looks like it has bubble levels to help you with alignment. Reading the review it looks like it needs tweaked, and is easy to do.
would I be right in thinking when you say altitude you mean estimating your height relative to a know feature?
As I understand it, altitude in astronomical terms is the angular height of an object over the horizon, azimuth would have been a better term.
If so any compass with a clinometer can be used - to a great orr lesser accuracy, such as the Silva type 15
or Suunto MC2
This link has some good brief descriptions:
http://www.zoom-one.com/distance.htm
That is indeed true, and we were also shown these. The Brunton type though really has this job nailed.
The other factor is that I have binned so many liquid filled compasses due to air bubbles that I really hate them now.
The Brunton is the best non liquid compass I've ever seen.
This is cheaper than the Silva 15 or Suunto MC2 and if it's even half as good as the Brunton I'll be very happy.
That's a brilliant compass. It's the original version of the M2 Artillery compass http://www.olive-drab.com/od_soldiers_gear_compass_m2.ph p and very precise. I bought one back in the '80's and it was a extremely pricey.
Doesn't look bad for the money and the fix for needle weight and dampening etc written in the review seems straightforward.
would I be right in thinking when you say altitude you mean estiamting your height relative to a know feature?
It's the angular altitude of something with reference to the position of the instrument. It's basically being used as a spirit level with a sight, and the angle between the very accurate spirit level and the sight is measured by a precision protractor.
Doesn't look bad for the money and the fix for needle weight and dampening etc written in the review seems straightforward.
If anything, the fact that I can open the thing up and tinker with it makes it even more appealing for me.
I like things that I can fix or adjust myself without having to send half way across the world to get serviced.
It's the very thing that hacks me off about liquid filled compasses that gets a bubble just because I get it cold or climb a mountain, Gods forbid I ever fly with the damned things...
with you now. The compass might be worth a punt.
Let us know how you get on with it Wayland.
Will do, I'm just wondering if it will get held up in customs.
I'm guessing there will be some duty to pay. (And probably an exorbitant handling charge from the post office.)
... I've been looking around for a light weight or pocket version to play with, even the Davis Mk3 sextant, £50 tho :(
A bit of string and a plastic ruler can be a lot cheaper. There must be better writeups than this one but it gives you the idea:
http://en.wikipedia.org/wiki/Kamal_(navigation)
Ahh but what price fun?
(although that does remind me to make a Kamal and others for next year's workshop - ta)
Looks like they make a damped version (http://www.alibaba.com/product-gs/313029969/DQL_8_Geological_compass/showimage.html) too.
Laurentius
09-08-2010, 21:29
On the subject of chinese knock offs, has any one bought one of those pound store Silva knock off's? I lost yet another compass yesterday (I'm not going to trust those nitize S biners any more for clipping anything to my belt loops) and I thought for a quid it either works or it doesn't. The immediate difference between it and the genuine article is that is is dry, not liquid filled, and not all that well put together, but it seems to point in the right direction so given my propensity for losing things, it's as well to have something in reserve. Whilst on the subject of poundland tat, some of it really is, I had one of those 9 LED torches, very bright and no mistake, but after leaving it in my car it fell apart when I took it out the other day.
Spikey DaPikey
09-08-2010, 22:13
If anything, the fact that I can open the thing up and tinker with it makes it even more appealing for me.
** Snip**
Gods forbid I ever fly with the damned things...
I think you need a plane to fly, not a compass :p
http://www.wayland.me.uk/assets/images/groooansmileyf.gif
On the subject of chinese knock offs, has any one bought one of those pound store Silva knock off's? I lost yet another compass yesterday (I'm not going to trust those nitize S biners any more for clipping anything to my belt loops) and I thought for a quid it either works or it doesn't. The immediate difference between it and the genuine article is that is is dry, not liquid filled, and not all that well put together, but it seems to point in the right direction so given my propensity for losing things, it's as well to have something in reserve. Whilst on the subject of poundland tat, some of it really is, I had one of those 9 LED torches, very bright and no mistake, but after leaving it in my car it fell apart when I took it out the other day.
Check every compas against a proven one preferably a good brand.
I have found knock-offs that were several degrees out and one that was 180 off. To with pasting the card I think
It's just arrived so first impressions:
It's solidly made, all the joints are good with no sloppiness and in fact some are slightly stiff which means they should have some good wear time.
It's reassuringly heavy, it feels like it has a heft like the British army marching compass but I don't think it's quite that heavy.
As suggested on the site review, the Southern end of the needle was a little high but it was very easy to pop the o ring holding the glass and slide the copper balancing wire a smidge towards the point to level it out.
The needle does hunt a little but seem to be very sensitive, it's sitting on my desk by my keyboard at the moment and I can see very slight movements as I hit different keys. I don't think I've ever seen such sensitivity in a liquid filled unit. If anything it does remind you that to take an accurate readings you should move away from substantial metal objects, including you knife in some cases.
There is a slight rattle from the needle, not uncommon in dry compasses, but when closed the needle is lifted against the glass by a button and so is silent.
The button can also be depressed and released manually to help the needle to settle.
The long sight does not have a fixed vertical position when folded out from the body. I don't see any disadvantage to this arrangement. It's stiff enough to stay where you put it and if anything it gives you a wider angle of sighting positions.
One advantage that the Brunton has over this one is that the sighting line on the mirror also bisects the clear window, making alignment through the window slightly easier. Being used to peep sights I'm not sure that will bother me but it may be a consideration for some.
The bulls eye level seems accurate enough to level the compass and the long level on the clinometer is sensitive enough for degree measurements, possibly even half degree. I will test it's accuracy against a known level later.
The screwdriver that is supplied is slightly too thick for the declination screw so I'll talk about that a bit later too.
Just been out in the workshop fixing the screwdriver, and a useful little detail came literally to light. there are luminous spots on the North side of the needle, the quadrants of the scale and the declination adjustment point.
With the screwdriver fixed, the declination screw moves the entire scale east or west. I only need 2° 02' W adjustment where I am (See correction below.) but the scale is marked for 30° either way. Incidentally, the small screwdriver head on the can opener of my SAK is thin enough to adjust this screw if needed.
On the Astro Nav talk, pteron mentioned the main problem with using these for star sights was not being able to see the level in the dark. I had a hunch about that which does look like it will work.
The levels are filled with a flourescent liquid as is common practice. So a small UV emitting mini led torch, pointed into the compass makes the level very clear in the dark while not disrupting night vision too much.
Although holding it is a little awkward it does seem to address this problem quite well.
( Checking the NOAA declination calculator site instead of the calculation based on the OS map gave a declination of 2° 40' W. see post below for details.)
Having just checked the long clinometer level against my builders level, there seems to be about a quarter of a degree difference.
I am inclined to trust the clinometer as it's level seems the more sensitive of the two.
Either way, ¼° (or 15' or arc) is probably more accurate than I could reasonably expect to get from a hand held sighting with clinometer anyway.
Obviously this cannot compare with the accuracy of a good sextant and could amount to as much as 15 nautical miles inaccuracy in position, but as I am unlikely to be carrying a sextant with me in most instances it certainly out performs a Kamal (http://en.wikipedia.org/wiki/Kamal_%28navigation%29) or similar makeshift methods.
For map work it suffers the obvious disadvantage of not having a built in protractor like a baseplate compass. This can easily be remedied buy using a separate one or even carrying a small baseplate compass as well, giving a back up too.
I should mention the case, it is reasonably sturdy and lined with thin closed cell foam. It is fit for purpose if a little ugly. I can see myself making a better one at some point but for now this will suffice.
The Brunton instructions suggest putting the top of the compass away from the press stud to protect the mirror from breakage. I am going to assume the same precaution is wise with this one too.
I will take it up my local fell this afternoon and give you some further impressions then.
Thanks for the write up Wayland.
So you are happy with it for the money?
Just got back from the fells.
I took some map bearings before I went, for features I knew I could see up there, A mill chimney at about 3km and a church tower at just over 2km. I had figures from a car park and a trig point a click apart so the distances vary slightly.
The car park bearings checked out exactly and to -½°. The trig point bearings were also exact for the chimney and -½° for the church tower. Closer examination of the 25K map show that the building has been overwritten with the church tower symbol. I used the centre of the square as my point but I think that may be incorrect on the ground. A small church length at 2 clicks is not too bad though I guess.
On the fell I also took some bearings from the same features, and a new one too, at a point in between my two reference points and used these to get a fix on my position.
The lines crossed within 2mm on the map, again my wandering church being the furthest out, and the other two being spot on a fence line almost exactly where I was standing.
This is by far the most accurate results I have achieved from such a test. I have never been given cause to actually doubt the accuracy of an OS map before.
All these bearings were taken using the long sights with the compass resting on solid points. In two cases dry stone walls and a wooden gate post for the position fix.
Hand held bearings were made a little more difficult by the hunting of the needle, but not impossible. For hand held readings you can brace the compass at your waist and sight using the mirror as shown in the Brunton Instruction Manual. (http://www.brunton.com/manuals/current/Compasses/Transit.pdf)
Something I should have mentioned is that the instructions supplied with the compass are in Chinese, so unless that isn't a problem you will want to check out the Brunton instructions anyway. The compass is more or less the same functionally.
Pros:
Capable of taking very accurate bearings with a little care.
Capable of measuring vertical angles.
Allows magnetic declination (or variation) to be set on the dial.
Solidly built.
Not liquid filled meaning no more annoying air bubbles.
Inexpensive for an instrument of this quality.
Cons:
No built in protractor.
Requires a bit more knowledge and skill to use to it's full potential.
Not liquid filled requiring more time for the needle to settle.
Fairly heavy and a bit bulky.
So, in conclusion: Is it good value for money? Well for me it ticks all the right boxes. Most of the "Cons" listed above do not bother me at all, although I do wonder about the damped version which seems to be about £40 on ebay. If I'd seen that before ordering I may have gone for it but I'm not too worried now.
On the whole I like this a lot.
It's not a fast compass to use and it's not something you would tramp along with in your hand, so it wouldn't suit orienteering for example. In practice I only tend to use a compass when I want to check something, and accuracy is what really counts then.
Yes, I think this is very good value for £26.
Great review. I think I might well give one of these a try...
I don't think you will be disappointed.
Gailainne
15-08-2010, 16:16
Excellent write up Gary, looking forward to getting mine.
I've just been back up the hill and taken bearings from the other end of the the wandering church.
Sure enough, there is the half degree inaccuracy. The symbol is definitely in the wrong place on the map.
I don't think I've ever owned a compass more accurate than a 25K map before....http://www.wayland.me.uk/assets/images/8823.gif
It could be one of the deliberate inaccuracies that OS introduce to catch people copying their maps
very temped by the damped version - have you got a link?
I like this.
I've already got a Silva Type 54 (actually badged Brunton, but it is made in Sweden by Silva) and it will measure bearings to 30 minutes or so. But it won't measure vertical angles, and I can think of times when this would be useful.
I guess if you sight Polaris you can work out your latitude?
I don't think I've ever owned a compass more accurate than a 25K map before....http://www.wayland.me.uk/assets/images/8823.gif
Have you ever used a Franny Barker? Beautifully damped, no bubbles, reliable, fast and accurate to 1/4 deg unsupported or even less if you support it (down to 4 minutes of arc with the mills version scale, +/- 15 minutes of arc guaranteed by Psyer-SGI). The Sylva type 54 is almost as good, either will deliver accuracy well beyond the point of usefulness.
I guess if you sight Polaris you can work out your latitude?
Well you'll also need a good horizon, or at least a bucket of water. :)
Not with a bubble sextant. I'm wondering if a pocket transit like Wayland's can be pressed into use for this.
The Francis Barker compasses are very nice, but no good for measuring vertical angles.
The Francis Barker compasses are very nice, but no good for measuring vertical angles.
Very true. How useful is that though? Generally, I dont even bother with declination. If you've got landmarks, you dont really need a compass.
Very true. How useful is that though? Generally, I dont even bother with declination. If you've got landmarks, you dont really need a compass.
All very true. Probably not useful for everyday use, but the things I was thinking of were:
Measuring angles of rock strata (dip) - it's original use.
Measuring the heights of trees. Thoreau did this annually to measure growth. I might want to do it when thinking of using a tree as a field-expedient antenna support, though I'm sure a guess would be good enough.
Teaching the kids trigonometry.
Celestial navigation - although it's never going to be as accurate as a sextant. Being a degree out gives you a 60 nautical mile error, so maybe not of practical use, but interesting nevertheless.
Predicting accurate acquisition of signal/loss of signal times for amateur radio satellites in mountain country (the standard software tells you when the bird comes over the horizon- great in the fens, but not here)
Having said all that, I might be just deluding myself in order to justify buying a new toy. And I [I]like[I] scientific instruments.
Did you know it has a vernier scale?
All very true. Probably not useful for everyday use, but the things I was thinking of were:
Measuring angles of rock strata (dip) - it's original use.
Measuring the heights of trees. Thoreau did this annually to measure growth. I might want to do it when thinking of using a tree as a field-expedient antenna support, though I'm sure a guess would be good enough.
Teaching the kids trigonometry.
Celestial navigation - although it's never going to be as accurate as a sextant. Being a degree out gives you a 60 nautical mile error, so maybe not of practical use, but interesting nevertheless.
Predicting accurate acquisition of signal/loss of signal times for amateur radio satellites in mountain country (the standard software tells you when the bird comes over the horizon- great in the fens, but not here)
Having said all that, I might be just deluding myself in order to justify buying a new toy.
Not sure about the above, but this...
...And I like scientific instruments.
...I can relate to. In fact I would possibly consider buying a genuine Brunton Pocket Transit for just that reason alone. It's really the main reason I bought a franny barker as for all practical purposes, the Silva 54 is a more useful compass. I just love the franny barker as a beautiful instrument. I've also got a very nice Russian stereo, oil immersion microscope (used to work in microbiology years ago), though I always wanted a Leica.
Did you know it has a vernier scale?Get thee behind me Satan. :D
On the point of sextants, my dad used to be in the royal navy and loves all those toys. So 13 years ago, I bought him an antique sextant for his 60th - £600 worth. I really should learn how to use it, it's a beautiful thing in amazing condition. It probably needs recalibrating now - dunno who does it these days, but they used to get calibrated by the national physics laboratory in teddington and each one carried a proof certificate. Lovely thing, havent a clue how to use it though.
On the point of sextants ... I really should learn how to use it ,,,
It just measures an angle, although as you've pointed out fairly accurately. A measurement gives you a position line, and like any other position line you need more than one line to get your position.
http://www.amazon.co.uk/Sextant-Handbook-Adjustment-Repair-History/dp/0070052190
The tricky bit isn't using it to make a measurement, but applying all the corrections* and doing the sums to get your position lines**.
* Instrument error, refraction, dip...
**Arcs of circles, which in the absence of errors intersect at your position, but if they really do intersect in practice then it's grounds for suspicion. ;)
I wouldn't waste money on calibrating an antique. You can get perfectly acceptable results when you get to know the instrument and you're never going to do much better than a few miles unless you're on land. :)
It just measures an angle, although as you've pointed out fairly accurately. A measurement gives you a position line, and like any other position line you need more than one line to get your position.
http://www.amazon.co.uk/Sextant-Handbook-Adjustment-Repair-History/dp/0070052190
The tricky bit isn't using it to make a measurement, but applying all the corrections* and doing the sums to get your position lines**.
* Instrument error, refraction, dip...
**Arcs of circles, which in the absence of errors intersect at your position, but if they really do intersect in practice then it's grounds for suspicion. ;)
I wouldn't waste money on calibrating an antique. You can get perfectly acceptable results when you get to know the instrument and you're never going to do much better than a few miles unless you're on land. :)
That book looks interesting, I might give it a go just as an acedemic exercise. The sextant I got for my dad looks like this (except it's all brass)...
http://www.dundee.ac.uk/museum/sextant.jpg
Dated sometime around 1910 to 1920 I think, it's had some kind of illumination thing retrofitted to it. I'm sure it'd need calibrating before it was any use.
The sextant I got for my dad ...around 1910 to 1920 I think, it's had some kind of illumination thing retrofitted to it. I'm sure it'd need calibrating before it was any use.
I don't know what the illumination thing might be unless it was to light up the scale so you could read it in the dark. The scales and the screw threads won't change much but if you're adamant about calibration buy the book. It will show you how to do it, you'll learn a lot about the instrument, and will be a lot cheaper than shipping it to NPL. :) They charged me something like 60 quid to calibrate a 12 inch ruler twenty years ago! You can play around with a sextant to get the hang of it by standing on a hill and measuring horizontal angles. Sort of like using a compass vertically in reverse. :)
Thanks ged, you know, I'm gonna give it a go dammit. I always thought I should at least learn how to use the thing, even if only a rough idea.
As well as the sextant, you need a clock and a nautical almanac to get a fix. However, IIRC there are programs for handheld computers that work as an almanac for celestial navigation (there was certainly one for the Palm Pilot).
I suspect celestial navigation has been all but forgotten by professional mariners. LORAN was hugely easier to use, and GPS easier still. Makes me wonder how they'd cope without it now.
TinkyPete
17-08-2010, 23:35
Great review Gary. I will certainly be looking into one soon hopefully :)
That book looks interesting, I might give it a go just as an acedemic exercise. The sextant I got for my dad looks like this (except it's all brass)...
Dated sometime around 1910 to 1920 I think, it's had some kind of illumination thing retrofitted to it. I'm sure it'd need calibrating before it was any use.
I've got the book - it has some useful stuff. I bought it because it claims to tell you how to service a sextant - it doesn't. Calibration needs collimators and other optical trickery and is very expensive and completely unnecessary unless you think the sextant has been dropped or massively mishandled. If it has, it probably needs retiring to the mantelpiece as once the arc is damaged the cost of repair will likely exceed the cost of a new sextant.
To check your sextant out is easy, shame you are oop North, as it is much easier to show than describe!
Basically you want to do the following:
1. To check for perpendicular error (of the index mirror) set the sextant to about 35 degrees and hold it out horizontally so you can see the arc and the reflected arc in the index mirror. There should be no step in the arc as it passes from direct view to reflected view. Adjust the index mirror (side screw) until the arc lines up. If it won't line up then the arc is bent or the index mirror frame is not perpendicular to the sextant body. It will look like this:
http://pteron.org/blog/wp-content/uploads/2010/08/IMG_0510-300x225.jpg (http://pteron.org/blog/wp-content/uploads/2010/08/IMG_0510.jpg)
2. Then check for side error (of the horizon mirror) by setting the sextant to 0 degrees and viewing the horizon with the sextant horizontal or a vertical edge (I often use a lighthouse) with the sextant vertical. The further away the better. You are looking to see if there are two images of the edge, one from the direct view the other from the reflected view. These should be co-incident and I find swinging the sextant from side to side to watch the edge move over the direct/reflected boundary works well. Adjust the horizon mirror until the images line up.
3. Finally of the ones you can do anything about, there's index error. Set the sextant to 0 degrees and sight a far away body, don't forget the shades on both paths if you use the sun. The images should line up. If they don't, you can adjust the index mirror (top screw) to make them do so.
You may find that adjusting the index error throws out the perpendicular and side errors so re-visit these checks. On my sextant it tends not to, but you may find you need to iterate around the loop once or twice especially if the sextant has gone way out of alignment.
Anything less than 3 or 4 minutes of error is traditionally left as on old sextants the adjustment screws work against a solid mounting and can crack the mirrors so you adjust as little as possible - this may be the case on your old sextant so be very careful! On a modern sextant, the opposite side of the mirror from the adjustment screw is held by a spring clip and so you are not creating any stress in the mirror by adjusting it so I tend to adjust for zero error.
The final check is for collimation error and you better hope it's fine because you can't really do anything about it! You sight on two stars at least 90 degrees apart using say the left hand side of the field of view. Then move the sextant so you are using the right hand side of the field of view. If the stars separate, you have a collimation error (the mounting of the telescope is not parallel with the sextant frame).
Hope this helps.
That's brilliant info, thanks. I'll have to print that off and go check it out.
Nice one gary - i've just ordered one - ive been looking for something like this at a decent price for a while
Cheers
Nick
Want!
http://www.armynnavy.com/catalog/catalog/images/black.jpg (http://www.armynnavy.com/catalog/catalog/product_info.php/products_id/2266)
Want!
http://www.armynnavy.com/catalog/catalog/images/black.jpg (http://www.armynnavy.com/catalog/catalog/product_info.php/products_id/2266)
Lovely instrument Andy, I did a writeup on the M88 (lightweight version of the M73) here...
http://www.britishblades.com/forums/showthread.php?t=82843
I've been away for a few days so sorry for the late reply.
very temped by the damped version - have you got a link?
No specific link but if you type in DQL-8 on ebay you get a couple of listings.
Did you know it has a vernier scale?
I have to add for the record, that the Brunton has a vernier scale but this Chinese copy does not. I do not know about the damped version, if anyone gets one it would be great to get some feed back here.
Lovely instrument Andy, I did a writeup on the M88 (lightweight version of the M73) here...
http://www.britishblades.com/forums/showthread.php?t=82843
Wow, great review Martyn. I need one even more now. But which one to get?
On a boat I'm not too worried about the baseplate as I have a plotter with me. I generally use a Plastimo sighting compass but this looks way more fun. Doubt I'll get half a degree though, 5 is usually good enough!
Wow, great review Martyn. I need one even more now. But which one to get?
On a boat I'm not too worried about the baseplate as I have a plotter with me. I generally use a Plastimo sighting compass but this looks way more fun. Doubt I'll get half a degree though, 5 is usually good enough!
Achh, man with a Franny Barker you'd get 2 degrees in a force 10 gale, the speed and damping on em is very impressive. :D
If you are going to lug it round with you, get the M88, if you are keeping it on a boat or in a vehicle, get the M73.
Be sure to check this website out...
http://www.trademarklondon.com/
...and say goodbye to your bank balance. :D
If I'm close enough to land to use a sighting compass in a F10 gale I shall probably be worrying about other things! :D
Thanks for the link - fortunately (for my bank balance) he doesn't have an M73 or M88!
Any idea how do they compare to the Brunton that Wayland mentioned at the beginning of the thread?
Price wise the M88 can be found for about £200 and the Brunton Composite at about £170 at the time of writing.
Thanks Gary. Any advantage to one over the other?
I think a comparison is in order :D
I wonder if they'll supply review samples?
Any idea how do they compare to the Brunton that Wayland mentioned at the beginning of the thread?
Brunton is a much bigger geological/surveyors compass with a load of bells and whistles, the Franny Bee is a military marching compass - it points north. :D
Did you see that little pocket sundial on the trademarklondon site? How cool is that thing? :D
Price wise the M88 can be found for about £200 and the Brunton Composite at about £170 at the time of writing.
You can occasionally drop on a good, used M88, I got mine off ebay for £100 on BIN. It's in perfect condition. A lot of em are in mils though, if you spot a cheap one in degrees, it's worth thinking about. Though Psyer-SGI will re-card em for a fee.
Brunton is a much bigger geological/surveyors compass with a load of bells and whistles, the Franny Bee is a military marching compass - it points north. :D
Did you see that little pocket sundial on the trademarklondon site? How cool is that thing? :D
Maybe I need both then.
Pocket sundial - very nice. Shiny shiny. Must not buy.
On the subject of converting a FB from mils to compass, and at the risk of running into the same criticisms from the mil purists, I used a guy called sea to science. I've no connection just a happy customer. I had an FB but had to sell it when times where hard, later had a little more money I bought a mils FB from eBay and got it converted. Conversion and compass cost about £110
Well as an experiment I've just taken my first star shot of Polaris from my back yard.
It wasn't easy, in fact I had to make a slight estimation as I couldn't really see the star and illuminate the level at the same time.
Although the UV led light worked well enough I don't think my eye was dark adapted enough.
The reading I got from the scale was 53° or maybe just a smidge under.
My location here according to the 25K OS map on Memory Map is 53°34'8"N 2°5"02.1"W So roughly 39 miles out on a first try. Make of that what you will.
I have an idea that might improve that, but I'll have to try that another night.
Just a thought - the florescent dye in the bubble level might well be flourescein: I use this to examine the eye for corneal abrasions. When doing this I use blue light, not UV. Might be worth trying.
I've just checked out a more up to date edition of my local 25k map, Mine was printed in 2002.
There is a 40' difference between the magnetic declination on the new map to the calculation based on annual change on the old one. that's a bit of a shock actually.
I've just recalculated my results using the new data and it puts the church back where it should be.
I think I'll be relying on the BGS (http://www.geomag.bgs.ac.uk/gifs/gma_calc.html) for this data in the future
I've just checked out a more up to date edition of my local 25k map, Mine was printed in 2002.
There is a 40' difference between the magnetic declination on the new map to the calculation based on annual change on the old one. that's a bit of a shock actually.
I've just recalculated my results using the new data and it puts the church back where it should be.
I think I'll be relying on the BGS (http://www.geomag.bgs.ac.uk/gifs/gma_calc.html) for this data in the future
That is a lot, but maybe it's a sign of where we live, that we expect our maps to be accurate to within a few feet or less? Besides, even though 40' is a lot, churches are pretty big, you wouldn't miss it. :D
I love hyper-accurate instruments, but for general purpose use, we dont really have much of a need for them.
Just a thought - the florescent dye in the bubble level might well be flourescein: I use this to examine the eye for corneal abrasions. When doing this I use blue light, not UV. Might be worth trying.
fluroscein works well under UV light -- I use it by the big styel at work testing drainage systems. When the "water" is very murky UV light often shows it up when other lights fail.
I've just checked out a more up to date edition of my local 25k map, Mine was printed in 2002.
There is a 40' difference between the magnetic declination on the new map to the calculation based on annual change on the old one. that's a bit of a shock actually.
That shouldn't have been a shock. OS maps show the approximate annual change in magnetic variation alongside the actual variation at the time of printing. On a pseudo-random Explorer Map (number 260 dated 2006 but variation figures given for July 2008) which happens to be on my coffee table the annual change in variation is given as 9'E. Than means in the eight years that gave you a change of 40', the change in Sherwood Forest would be nearer 72'. Of course the change isn't constant from year to year.
When I started Duke of Edinburgh's Award in 1967 the first thing they told us about maps was "A map is out of date as soon as it is printed." :)
"2002 Declination 3°46' west, Annual change 13' east" 13' x 8 = 1° 44' east: Final result 2° 2' west.
As you can see, I had already calculated according to the map for the annual variation, but their formulae was still incorrect by 40' compared with the actual declination.
That is the inaccuracy that surprised me.
I had already calculated according to the map for the annual variation, but their formulae was still incorrect by 40' compared with the actual declination.
That is the inaccuracy that surprised me.
I understand. As I said, it isn't a constant annual change. Maybe this (http://www.ngdc.noaa.gov/geomag/declination.shtml) will help.
As with all estimates you expect a slight variation, I was just surprised at the size of it.
I have often used the map calculations without thinking much about it. I shall be less casual about it from now on.
big_swede
29-08-2010, 18:24
I hate you guys so much right now. Just bought the dampened version.
Let me know how you get on with it.
Laurentius
29-08-2010, 19:23
My problem with old OS maps is that in the meantime between my being to mean to by a new one, someone has excavated a quarry across what used to be the path in my old map.
I've been playing around with one of these (http://www.maptools.com/products/PocketCorners.html) to make up for the lack of a built in protractor.
http://www.maptools.com/products/images/PocketCorners_Image.gif
I have to say that with the addition of a piece of thread from the centre hole these far out perform a baseplate compass because I can measure angles right across the page.
It's also just the right size to fit into the compass case with the transit.
I haven't seen exactly that pattern of square protractor before, where did you find it? The closest I could find was the military protractor, but it doesn't seem to have a central hole:
http://www.survivaliq.com/navigation/direction_par5.htm
http://www.deltagearinc.com/Navigation/Protractors/SquareMilProtractor.htm
When it's used with a bit of string like that it's called a Sutherland Plotter:
http://www.starpath.com/catalog/accessories/1852.htm
That one and some others have the central hole, but they don't have the scales that yours has:
http://www.pooleys.com/prod_detail.cfm?product_id=98
http://www.thomasgunn.com/onlineshop/Shop/IndividualProduct.aspx?TopLeve lCategory=IN&CategoryTop=&ProductId=3848
You can draw a course line from this:
http://marinestore.co.uk/PL10560.html
Where the Bretton plotter just gets in the way: :(
http://chandlery.marinestore.co.uk/search/index?filters[category][]=Navigation+Instruments&filters[category][]=Navigation+Instruments
Some of them can get a bit silly:
http://www.sailgb.com/p/three_arm_protractor/
I've always preferred using just a couple of triangles:
http://marinestore.co.uk/MD290290.html
But still no central hole. :(
There is a link on the word "these (http://www.maptools.com/products/PocketCorners.html)" above, but they are from an American company called "Maptools (http://www.maptools.com/index.html)" that do a great range and will post to the UK.
Ordered mine on the 19th August - as of today its awaiting delivery of new stock
So folks dont rush to buy one just yet
Annoying as i wanted to try it out on a trip up the pen-y-fan this weekend
c'est la vie or as the french say thats life
cheers
Nick
There is a link on the word "these (http://www.maptools.com/products/PocketCorners.html)" ...
:argh: I totally missed that. I've been thinking I ought to do something to make links like that more obvious because with my crappy laptop screen and my even crappier eyesight I often miss them, so I guess I just got some added impetus! Thanks. Did you get yours from America?
I ordered mine directly from their site.
The postage was pretty cheap and fairly fast.
I haven't seen exactly that pattern of square protractor before, where did you find it? The closest I could find was the military protractor, but it doesn't seem to have a central hole:
I made mine by doing a quick google search for 'Printable Map protractor' saved the file and then took it along to a copy store where they printed them off onto Acetate sheet and then laminated them..
I took along a 1:50K and 1:25K map to check the scaling was right after copying.
Result a pile of useable flexible protractors for $10.00.
Pop a hole in the middle add in string and you're sorted for most mortal navigation tasks..
They work well for entertainment value with the M73 I have and also were ok with the USGI M2 and USGI lenstatic I had...
The Square US Army style protractor is better to use then the RA type IMHO...
Have fun...
John
jamesraykenney
08-09-2010, 06:10
It just measures an angle, although as you've pointed out fairly accurately. A measurement gives you a position line, and like any other position line you need more than one line to get your position.
http://www.amazon.co.uk/Sextant-Handbook-Adjustment-Repair-History/dp/0070052190
The tricky bit isn't using it to make a measurement, but applying all the corrections* and doing the sums to get your position lines**.
* Instrument error, refraction, dip...
**Arcs of circles, which in the absence of errors intersect at your position, but if they really do intersect in practice then it's grounds for suspicion. ;)
I wouldn't waste money on calibrating an antique. You can get perfectly acceptable results when you get to know the instrument and you're never going to do much better than a few miles unless you're on land. :)
He could make a cheap artificial horizon and learn to use it on land easily... A clue... You can use water instead of mercury for the liquid... Though I would LOVE to have one of the old ones with the mercury reservoir.
I remember when my father was taking Celestial Navagation school courses by mail. He got certified and taught Celestial Navigation classes for the Coast Guard Auxiliary.
I HOPE that those textbooks and workbooks did not get thrown out!
The thing is, that the easy way to do it requires the use of the Nautical Almanac for the current year.
If you want something a little more universal, you can get the Astronautical Almanac for the current decade and with a little spherical trigonometry, you can do the same thing...
If you have a programmable calculator you can do the equations quite easily though... Even if you do not know spherical trigonometry.
jamesraykenney
08-09-2010, 06:32
Well as an experiment I've just taken my first star shot of Polaris from my back yard.
It wasn't easy, in fact I had to make a slight estimation as I couldn't really see the star and illuminate the level at the same time.
Although the UV led light worked well enough I don't think my eye was dark adapted enough.
The reading I got from the scale was 53° or maybe just a smidge under.
My location here according to the 25K OS map on Memory Map is 53°34'8"N 2°5"02.1"W So roughly 39 miles out on a first try. Make of that what you will.
I have an idea that might improve that, but I'll have to try that another night.
You need a detailed star map of the north polar region of the sky... Polaris is NOT at North. It changes a little every year, but not much. The finder scope on my telescope has a circular grid that you use a circular slide rule device to calculate where in the eyepiece on the grid that you should see Polaris to polar align the telescope. You put in the time of day and the year and a little dot appears in a circular slot corresponding to the grid in the eyepiece. The year setting moves the dot inward and outward in the slot and the time and date moves it around the slot. Made polar alignment a lot easier.
jamesraykenney
08-09-2010, 06:42
Price wise the M88 can be found for about £200 and the Brunton Composite at about £170 at the time of writing.
And I thought my K&E(Keuffel and Esser) Pocket Transit for around $99.00 to $120.00 I thought the Brunton was better built but the K&E had the altitude scale vernier on the bubble arm tapered so that the scale had very little parallax error as the scale was only about a mm or less from the base scale. The Brunton had the edge of the scale something like 5mm above the base scale and you had to make sure that your eye was RIGHT in line with the center of the vernier.
jamesraykenney
08-09-2010, 06:50
I've been playing around with one of these (http://www.maptools.com/products/PocketCorners.html) to make up for the lack of a built in protractor.
http://www.maptools.com/products/images/PocketCorners_Image.gif
I have to say that with the addition of a piece of thread from the centre hole these far out perform a baseplate compass because I can measure angles right across the page.
It's also just the right size to fit into the compass case with the transit.
There is a website where they post all kinds of these things as PDF files so that you can print them out on transparency 'paper' and use them... If I can find it, I will post it. They sell them also, if I remember correctly, but I do not think that they make much profit on them!
jamesraykenney
08-09-2010, 06:59
<snip>
Some of them can get a bit silly:
http://www.sailgb.com/p/three_arm_protractor/
<snip>
Do not down the three arm protractor, we used them on the boat when you needed to find your position FAST and RELIABLY. You set the THREE bearings you get from your instruments and just line them up with the objects on the map. You take RELATIVE bearings, not compass bearings. So the protractor center shows your boats position and direction with one step, no compass needed.
jamesraykenney
08-09-2010, 07:05
There is a link on the word "these (http://www.maptools.com/products/PocketCorners.html)" above, but they are from an American company called "Maptools (http://www.maptools.com/index.html)" that do a great range and will post to the UK.
That is the site I was talking about! Their download page is HERE (http://maptools.com/FreeTools/). Look at the very bottom of the page for the category and it will take you to the download page for that type.
I looked at the downloads which are really useful but I made a few purchases in the end because I doubted whether I could produce the same sort of quality as the tools they supplied.
They were not expensive and the quality is indeed very high.
Do not down the three arm protractor, we used them on the boat when you needed to find your position FAST and RELIABLY. You set the THREE bearings you get from your instruments and just line them up with the objects on the map. You take RELATIVE bearings, not compass bearings. So the protractor center shows your boats position and direction with one step, no compass needed.
That's dangerously wrong on three counts.
Firstly it is not safe to sail without a compass, or to ignore it when taking bearings. It provides a valuable check on the bearings that you take for no extra effort.
Secondly if you take three magnetic bearings of navigational marks with a compass, a gross error will immediately be obvious when you plot them, because you won't get anything like a reasonable 'cocked hat'. There is redundancy in the measurements, because if you use a compass (and assuming you're awake) you really only need two bearings to get a position. If you take three bearings relative to the ship's heading then (a) the heading may have been different for each bearing, and more importantly (b) a gross error may not be obvious. If the boat's heading is unknown and the navigational marks are not widely separated then there may be no redundancy in the measurements at all (and you probably haven't been doing what any prudent navigator should do anyway).
Thirdly even if the heading is constant for the measurements of the bearings, the use of bearings relative to the ship's heading gives you the ship's heading at the instant of measurement, not its course. Tidal streams and perhaps leeway mean that the course over the ground will differ, sometimes very substantially, from the heading.
Finally you don't use a map when sailing, you use a chart. Hopefully one that's been corrected up to date.
Out of the bunch I ordered to try out, I've decided I like the 25k version of this (http://www.maptools.com/products/UTMGrids.html) the best.
http://www.maptools.com/products/images/UTMGrid24_ProductImageBig.gif
I very rarely us anything but 25k maps anyway so I don't really need the other scales, it still fits my compass case and with the addition of a tiny hole drilled in the centre I can use it with a thread for bearings as well.
The extra lines and dots on the romer make it much easier to line up on the grid while taking a thread bearing from a point off centre.
Out of the bunch I ordered to try out, I've decided I like the 25k version of this (http://www.maptools.com/products/UTMGrids.html) the best.
I feel a Group Buy coming on. Any takers?
bilmo-p5
09-09-2010, 10:11
I feel a Group Buy coming on. Any takers?
I'd be up for a 25k corner ruler/roamer, or two.
Has anyone who ordered the damped version got one yet?
Any thoughts?
I would take two of those 1:25k overlays if poss. thx!
They're pretty good, thinking about ordering a military and a 1:25000 what was the delivery time on yours Wayland?
Can't remember exactly.
About a week or so I think.
big_swede
19-09-2010, 18:16
Hello wayland. I'm afraid I skimped out when I realised the postage was 20 bucks compared to zip from DX so I went with the undampened version as you did. Hasn't arrived yet, also ordered a pair of cammenga lensatic compass copies which arrived on friday. The quality was varying, not really happy with them as the differ a bit from the original, but for $6 I can't really complain, I think I even prefer them over my silva baseplate compasses. I think I will use a silva button compass (http://www.silva.se/en/Products/Compasses/Orienteering-Series/?productId={5B1047F5-A5B1-49BF-9451-A3F50B8A2C3E}) that comes with as a plastic paper clip on the map, for quick navigation on the go, and either the transit or lensatic for taking bearings, tri/biangulation and dead reckoning. Oh and as my ranger beads seems to have gotten legs and taken off, I made a new set from plastic hobby beads and climbing string. Much more colourful and cheerful, which is good for essential navigation equipment. Cost naught as well.
Sorry for the random navigation rambling :)
Just to tlet you all know my transit compass still hasnt showed up yet - its been over a month
Cheers
Nick
Mine was about a week Nick.
Were they waiting for stock or some such?
waiting on stock it says on the tracker
Cheers
Nick
big_swede
22-09-2010, 12:19
I just picked up mine. It's gorgeous. I will tinker a bit with it tonight.
Has anyone who ordered the damped version got one yet?
Any thoughts?
My one has arrived this morning. Will play over the weekend and post back!
big_swede
22-09-2010, 17:12
So, now I have adjusted the needle and greased it a bit. It was very sensitive at first, but now it's quite okay. Gonna try to do a field test with this, a cammenga copy and a few silva compasses this weekend. Also set the magnetic declination.
big_swede
28-09-2010, 11:04
After the short trial I did on sundays walk I think that I won't really use transit knock-off for actual navigation. The american walking compass is more apt for the job IMHO.
Did you have problems with it?
big_swede
29-09-2010, 07:26
Did you have problems with it?
No not really, after adapting the needle and greasing up the contact point it's okay to use when stationary, but walking with it (following a bearing) it's not really good. It skips and jumps too much. A bit too sensitive, at least compared to the marching compasses. I haven't ruled it out completely yet though. Might wanna do some more field testing. I really like the weight and heft it has, also like the feeling of quality. Considering selling it and buying the dampened version. Those $20 in shipping seems okay now.
As I mentioned somewhere, I don't think its really suited to marching or orienteering.
I tend to use it to note a point on my bearing line and walk that way.
I would be interested in how much better the damped version is but I think I would still use it the same way.
big_swede
29-09-2010, 10:00
As I mentioned somewhere, I don't think its really suited to marching or orienteering.
I tend to use it to note a point on my bearing line and walk that way.
I would be interested in how much better the damped version is but I think I would still use it the same way.
I mainly go through pretty thick flat forest areas with the odd marsh land and lake, very few landmarks usually. I have to rely on micronavigation and compass bearings, since it's usually a case of dodging trees every other step. For me at least I check bearing every other twenty meters, or if it's something critical, and I'm not alone, I have a point man I correct every now and then. With the 'tlansit' (chinglish/engrish for transit) I would have to grind to a complete halt more or less. But as you already concluded, before I bought the compass, it's not optimal for walking. I too will use it, and I thoroughly enjoy owning one. :rolleyes: I also intend to use it for some caving, good for mapping out caves with the inclinometer.
Wayland, btw, have you thought of making some kind of adapter to use it with a tripod? I sometimes use a tripod for landscape photography and it would be fun to play surveyor or prospector. The tlansit lacks the grooves that allows the transit to attach to a tripod adapter. I thought of using a clamp from bogen or just epoxy glueing a 1/4" nut to some clamp.
(Don't interpret the first paragraph as my areas being hard to navigate, they really aren't, if you know how to read a map, you seldom even need a compass, I just like navigating for the navigations own sake, it's a nice sensation being dead on)
My tripod has too many ferrous parts to us unfortunately otherwise it would have been a good idea.
Brunton sell a completely non magnetic one for the job with theirs.
big_swede
29-09-2010, 18:12
My tripod has too many ferrous parts to us unfortunately otherwise it would have been a good idea.
Brunton sell a completely non magnetic one for the job with theirs.
I suspect that would be the case with my benbo too then. Hmm, I thought it was just the spikes and the screw that would made of steel, and since it's cheap stainless I suspected it to be quite safe, will have to check that out. Might try and make a DIY wooden tripod then. Or somehow make a fugly adaption of an old painters easel I have lying about somewhere.
Mine finally arrived today ordered on the 19th auguet arrived 29 October - 9 weeks waiting for new stock
The glass ring is quite loose and it drops out easily losing the needle and the lock arm and bearing. The needle won't balance no matter where i put the balance wire.
Needless to say im a little dissapointed but i shall tinker for a while to see if i can sort it out
cheers
Nick
That's sad to hear Nick, very different from my experience...:(
shaggystu
01-11-2010, 13:38
I feel a Group Buy coming on. Any takers?
only just noticed this, i'd be interested.
cheers
stuart
finally figured out why the needle wouldnt balance - there was an electric screwdriver in the drawer directly below it now it works fine - and now i moved it away from the telly its very accurate.
the o ring securing the glass is not particularly tight but it seems to do the job.
Having got it set up i quite like it - taking inclination readings is something of a fine art watching the bubble in the mirror whilst keeping it on target - so innaccuracy is more a feature of poor operating than poor equipment but i am not uncomfortable with that - when the kit is smarter that i am it means that its not time to look for an upgrade.
As a basic transit compass for taking bearings in the field its great - i tend to sight it in and depress the small locking pin to fix the needle and them read the angle with the needle locked.
The needle settles reasonably quickly and extending both the front and back sights gives a nice long sight radius which gives a lot of confidence that the bearing is accurate, the sight radius is more than 3 times that of a good old army marching prismatic compass and i like that.
Near as i can tell the bubbles are spot on - certainly good enough for feild measurement.
I might wish for some form of tripod fixing for more accurate angle measurements and i am trying to think up something - any ideas anybody?
Nevertheless i am pleased with it for the money an would certainly reccommend it as a good aquisition
Cheers
Nick
I'm glad it's worked out for you, I think they are a great product for the money.
very nice compass, indeed!
after going through a pile of compasses over the years; some freezing, or being damaged,or falling apart; i decided to spend more cash this time.:)
i think ive spent more money over the years replacing compasses than what my new one cost.
i just got my new Cammenga Tritium version, last week! :D
apparently they are issued to the US military.
Probably the best compass i have ever owned.
PROS: durable, no water filling, folding, tritium, very fast!
CONS: a bit bulky, price.
http://i360.photobucket.com/albums/oo41/alzathoth/EDC/cammenga3H.jpg
http://store.cammenga.com/scripts/prodView.asp?idproduct=47
very nice compass, indeed!
after going through a pile of compasses over the years; some freezing, or being damaged,or falling apart; i decided to spend more cash this time.:)
i think ive spent more money over the years replacing compasses than what my new one cost.
i just got my new Cammenga Tritium version, last week! :D
apparently they are issued to the US military.
Probably the best compass i have ever owned.
PROS: durable, no water filling, folding, tritium, very fast!
CONS: a bit bulky, price.
http://i360.photobucket.com/albums/oo41/alzathoth/EDC/cammenga3H.jpg
http://store.cammenga.com/scripts/prodView.asp?idproduct=47
I can see from the Net that you're not a spammer, but your post especally as it is your first on this board comes across as a bit spammy. but anyway welcome to the board.
I think that is a bit unfair, it was on topic and didn't include a single pharmacy link. ;)
http://www.wayland.me.uk/assets/images/welcome1.gif Welcome aboard.
The Cammenga is reputed to be a good tool, I've only ever handled copies so I'm not best placed to comment. But they seem OK.
The US military issue two compass' the Cammenga and the Brunton Transit which is specifically for fire control from what I gather.
I guess it's like the Brit. army using baseplates for general purpose and Prismatics for precision work.
I can see from the Net that you're not a spammer, but your post especally as it is your first on this board comes across as a bit spammy. but anyway welcome to the board.
i am usually a man of few words, and tend to lurk online and absorb the knowledge this, and other forums provide. i try to help out others when i can, but i rarely comment, mostly due to a few rude or unruly individuals,... just testing the waters... ;)
mac
Mostly the waters here are very pleasant. http://www.wayland.me.uk/assets/images/canoe.gif
Hope you enjoy your stay.
Humpback
20-01-2011, 00:31
Wayland
I was impressed with this compass when re-reading this thread at christmas and ordered one which came today. The adjustment of the needle was easier than I thought. I agree with you that the compass is good value for money and that a magnifying glass is required too! As yet I can't locate your later thread with the hand made case so I'm off to your web site to see if it was there I saw it. Thanks for the review.
I haven't made a case for it yet. I've been too busy... http://www.wayland.me.uk/assets/images/willynillycopy1.gif
Humpback
24-01-2011, 19:07
I was sure you had! Anyway enjoyed your website again - found a few new things. I especially like the saami needle case. I hivered and hovered about buying one in Norway a little while ago and in the end didn't, which I have regretted ever since.
regards Alan
demographic
13-08-2011, 20:39
I got mine from another member here this week and overall I like it, its solid and seems accurate.
It was in perfect condition (as described) and the flat screwdriver fits the declination slotted screw with no modifications needed.
No problems whatsoever with the transaction with tobes01 and as far as I'm concerned he's very good to deal with.
I do have a bit of a problem with the needle hunting though.
Well, actually while I wait for it to settle down it hunts, gathers, sets up camp, carves a bleeding spoon, makes a basket and digs a latrine.
Its good but its not fast by any stretch of the imagination.
Still, I like weird and wonderful instruments and the price I paid was perfectly fair.
I'll have more time with it before too long and will give comments as I think of them.
Rub the tiniest smear of Vaseline on the needle tip with a cotton bud and see if that helps.
It did with mine.
demographic
13-08-2011, 22:25
Rub the tiniest smear of Vaseline on the needle tip with a cotton bud and see if that helps.
It did with mine.
I'll give it a bash, thanks.
I read it in the review but the chap never said he had done it IIRC so I would always rather hear from someone woho has done than one who read it.
Ta Muchly.