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Can you recommend a magnetic compass for Benchmarking?


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Well, on last weekend’s Benchmarking trip somehow our 30-year-old $10 lensatic compass did not make it home with us.

(We only have an automotive GPSr and it does not have much of a compass, so we rely on a magnetic compass.)

 

- Can you recommend a compass to use for Benchmarking purposes?

 

Is there such a thing as a magnetic compass that you can adjust to accommodate declination? (Sorry if that is a dumb question)

 

Thanks for any help.

 

The TillaMurphs

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Hi TM--

 

I just purchased this Suunto baseplate compass. It has little "bumpers" on the outside of the capsule that make it easy to turn (even with gloves on), is declination-adjustable, shows the intermediate cardinal points on its capsule (NE, SW, etc), and will work as a clinometer (slope angle measurer) if you need it. It is very light and just sits in my breast pocket, where it's always easy to reach.

 

Another option is a sighting compass. like the Silva Ranger. This one is a little thicker and heavier than the Suunto baseplate one, since it has a pastic "clamshell" cover that snaps down over the baseplate when it's not in use and contains its sighting mirror. Some people like a sighting compass, since they think it's easier to use in taking a bead on a distant point and measuring its bearing from where you are. You bend the mirror toward you at about a 45d angle, which lets you see the reflection of the compass dial in the miror while you sight over a notch on top of the mirror and read the bearing of the compass needle as it's reflected. It is also adjustable for declination, and I believe it has the Suunto's other features as well. I have used an earlier model of this one for many years, but wanted the Suunto because its faster to "draw and shoot". :laughing:

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pqriq,

 

Thank you for information on those two compasses. Since you got me started, I did some research and found out the Silva Ranger that you can buy now is not made by the same company that used to make it. The newer product seems to be disappointing to people who liked the original.

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pqriq got me started looking at some other ideas. It looks like, unlike my old lensatic compass, there are many models with either a declination scale or an adjustable declination (or both). Is a fixed declination scale satisfactory, or is it worth it to pay extra for adjustable declination?

 

Where we live (northwestern Oregon) declination is a significant factor (about 16deg 43’ E).

 

Here would be my wish list:

 

- be able to handle up to 17 deg of declination

 

- have a flip cover or clamshell (I am used to having this on my lensatic)

 

- has the most important features necessary for benchmark hunting (this is the ONLY thing we will be doing with this particular compass). This is the part where I really need help from you folks. We are just getting into benchmarks where we have a NEED to use the box score and reference and azimuth marks. We planned to keep plugging along with our old compass until we got farther into benchmarking – we figured by then we would know exactly what we needed. However, with the loss of our compass last weekend our timetable has moved up.

I see that REI currently has the Suunto MC-2G on sale ($50): Suunto MC-2G

 

They also carry the Brunton 15TDCL for a similar price ($55): Brunton 15TDCL

 

Any thoughts on either of those?

 

Here are some online pros and cons I have read about the MC-2G (any thoughts about these comments from 2 different reviewers?):

 

- "As a geologist and outdoorsperson, I've used many compasses over the years, Brunton, Nexus, Silva and Suunto. The MC 2G is the only baseplate compass I've used that has the same sighting hole at the base of the mirror that geologist's pocket transits have. This is a brilliant feature. It makes it far easier to obtain an azimuth."

 

- "The MC-2G lacks the tapered cover like that on the Silva Ranger, which gives you a much better view of the azimuth in the mirror. This makes it hard to take quick bearings using the mirror. However, it does force you to adjust the mirror to the correct angle."

 

The Suunto and Brunton are a bit more that we wanted to spend, but if our next compass lasts 30 years like my previous compass then I guess the price is OK.

 

I apologize for all the newbie questions. The loss of our compass means we have to buy a new one sooner that we had anticipated.

 

Thanks,

 

The TillaMurphs

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Based on your comments above, this is probably out of your price range but my recommendation would be the Suunto KB-14 Azimuth Model compass with declination adjustment.

 

These are accurate direct-sighting compasses you put up to your eye, so there is no fussing with mirrors and getting arrows and needles more-or-less lined up. Also, unlike the compasses you've mentioned which only have markings every 2 degrees, the KB-14 azimuth model has markings every 0.5 degrees. The KB-14 offers ease of use and accuracy, but at a little over twice the cost of the models you've mentioned.

 

As to your question about "fixed declination scales versus adjustable declination," I not sure I know what you are referring to when you say "fixed declination scale." All the compasses I have, such as the Silva Ranger, etc have a declination scale which you set to your local declination. So, they all are "adjustable," but once you set it, it is fixed until you decide to set it to another value.

Edited by tosborn
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In North Carolina, we don't have to deal with such severe differences between True and Magetic North. (16 degrees--Wow!) So I use an inexpensive (ten dollar) plastic sighting compass from REI, Dick's Sporting Goods, etc.

 

Mine hangs around my neck. That keeps it handy. It assures that it will get home with me. If it gets demagnetized accidently, it's not a great loss. And hanging from a red cord, it is very visible--as in supplementing my benchmarking "uniform". (Confidential comment to the Ladies: Please try to ignore the color clash with my red vest. No, I'm not being initiated into the Red Hat Club.)

 

I can see that if one were dealing with a consistent sixteen-degree variance, a fixed adjustment would be desirable. So when you find something that works, try to modify it to hang around your neck, for security and convenience.

 

I may have a spare red cord, if you need it.

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Surveyors have used the Silva Ranger for many years as a favorite sighting compass, but recently the design has changed and they seem to be more cheaply constructed and we have even gotten shipments of defective ones.

 

The kind that actually has two mirrors in the top lid, the mirrors are poorly fixed with simple double sided tape. The design change provided a sighting slit through the lid, but as a result you have a non planar dual cheap mirror that can fall apart. They may have fixed this defect, but be aware. Originally it was a single piece mirror with a line inscribed on the middle of it. There are a number of places on line that sell the Silva Ranger at $39.95 or so. But then you can't see what you are buying, or many online sites do not picture the product they actually currently have in stock to send you.

 

Silva is now marketed or owned by an outfit called Tech^4o. http://www.tech4o.com

 

For a simple compass, the Brunton 9020G Classic Compass is one of the few I have seen that does have a mechanism for setting off the local declination, but there is no sighting mechanism. It is, however, very inexpensive.

 

Also be aware that there are quadrant compass' and azimuth compass scales. Since your box score is in azimuth, that type may be preferred, but if you do anything with bearings then a quadrant scale is preferred.

 

- jlw

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If we want to get into instruments that are no longer in production....

 

or ones that are but are of a higher class...

 

For those who are more serious about using a compass for surveying there are what we would sometimes refer to as logging compass' or surveying compasses. Another term is "staff compass" which describes the normal use with a jacob staff. K&E was one significant maker and 4-4.5 in. needle models come up frequently on ebay and go for from $100-$200. Then you need to be aware of how to mount it. Some have tripod mounts and most logging type compasses come with an attachment for what is called a jacob staff. Those are hard to find also, but can still be obtained. Their principal purpose was to allow retracement of PLSS lines in the woods and some reasonably accurate line marking.

 

Warren-Knight produced one of the last high quality compasses of this type, referred to as the "Sipe-Sumner" compass, it is very high quality with a 6-7 inch needle. Sipe was LS #1 in West Virginia and wrote an excellent book which is still readily available on compass surveying. A number of tests he discusses in the book illustrate the high degree of accuracy possible for running lines with such instruments. Some of his tests are with a compass with a 4" needle which is probably a K&E.

 

A 19th century survey compass is even more refined and typically a 5-6 inch needle and sight vanes 15 in. apart. The slit/wire sites on the Sipe Sumner and K&E compasses are pretty good also without requiring the same size for the instrument.

 

- jlw

Edited by jwahl
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Hi Tillamurph,

 

I'm guessing you're near Tillamook, I'm in Vernonia. Finding Benchmarks out here seemed like a fun pastime. I don't know how much you are willing to shell out on a compass, but the brunton pocket transits are very nice tools in the higher end of the spectrum. I do like the idea of the older forestry transits put to a second life. I am going to look into that myself...

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Hi Tillamurph,

 

I'm guessing you're near Tillamook, I'm in Vernonia. Finding Benchmarks out here seemed like a fun pastime. I don't know how much you are willing to shell out on a compass, but the brunton pocket transits are very nice tools in the higher end of the spectrum. I do like the idea of the older forestry transits put to a second life. I am going to look into that myself...

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I am still looking. I really appreciate all the help from you guys so far.

 

Based on your comments above, this is probably out of your price range but my recommendation would be the Suunto KB-14 Azimuth Model compass with declination adjustment.

I would REALLY like to have one of those (or Z15’s K+E Recon compass). They seem like they would be perfect for Benchmarking. Alas, they are out of my price range for now.

 

Other things I have learned:

I played with a Brunton 15TDCL and looked at a Suunto MC-2G (that was held hostage inside its clamshell packaging). The Brunton just seemed easier to read than the MC-2G. From online research, it looks like the Brunton 15TDCL is actually what used to be the original Silva Ranger.

 

I would still like to know if any of you Benchmarking pros have any thoughts on this comment that I found online:

- "As a geologist and outdoorsperson, I've used many compasses over the years, Brunton, Nexus, Silva and Suunto. The MC 2G is the only baseplate compass I've used that has the same sighting hole at the base of the mirror that geologist's pocket transits have. This is a brilliant feature. It makes it far easier to obtain an azimuth."

 

I'm guessing you're near Tillamook, I'm in Vernonia

Hi Michael. A pretty good guess. The name is derived from us spending a lot of time in the Tillamook National Forest in combination with the name of our dog (Murphy).
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I bought a Silva Ranger after taking an orienteering class at REI; it was one of the models recommended by the teacher. However, that may have been before the manufacturing change, as mine does not exhibit the problems mentioned in recent REI customer reviews. I notice that the Brunton 15TDCL is the same price, so that might be a good alternative for you.

 

Patty

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I’m more familiar with this type of compass.

 

3in1_Military.jpg

 

It has a sight wire to line up on the “target” and a lens to see the reading on the dial. It’s pretty easy to understand. It does not have an adjustment for declination.

 

Most of the compasses discussed in this thread have a mirror. From the pictures I can’t figure out how you would use that.

 

Can somebody explain how to use it, or at least direct me to a web site that explains it?

 

Thanks

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I bought a Silva Ranger after taking an orienteering class at REI; it was one of the models recommended by the teacher. However, that may have been before the manufacturing change, as mine does not exhibit the problems mentioned in recent REI customer reviews. I notice that the Brunton 15TDCL is the same price, so that might be a good alternative for you.

 

Patty

Just won these:

One Sunnto, one Silva.

Still in the market?

Yesterday I bought the Brunton 15TDCL. (I posted about it last night in this thread but the server seems to have eaten my post??) Today the 15TDCL is going to get a good workout. Been planning this trip all week and will drive 120 miles one way just to look for 5 benchmarks.

 

AZcachemeister, thank you for the kind offer though.

 

 

Most of the compasses discussed in this thread have a mirror. From the pictures I can’t figure out how you would use that.

 

Can somebody explain how to use it, or at least direct me to a web site that explains it?

 

You fold the mirror partially open, sight through the slit/wire in the cover to the object you want to take the bearing of, and then use the mirror to read the compass. This way you can see the bearing object AND read the compass at the same time.

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Most of the compasses discussed in this thread have a mirror. From the pictures I can’t figure out how you would use that.

 

Can somebody explain how to use it, or at least direct me to a web site that explains it?

You fold the mirror partially open, sight through the slit/wire in the cover to the object you want to take the bearing of, and then use the mirror to read the compass. This way you can see the bearing object AND read the compass at the same time.

 

OK, thanks TillaMurphs. That looks easy. I’ll have to go to my neighborhood surveyors store to see what they have. Maybe I can play with one a little to see if it is better than what I have.

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OK, thanks TillaMurphs. That looks easy. I’ll have to go to my neighborhood surveyors store to see what they have. Maybe I can play with one a little to see if it is better than what I have.

 

Other than the declination adjustment, those mirrored types will have little advantage over the lensatic type in your photo. Of course, there is a wide range in quality for either type, so you can't compare a top-quality baseplate/mirrored unit to a cheap Taiwan plastic 'lensatic style' unit.

 

Either of the compai :blink: in my post above are available to anyone who wants/needs one. PM me if interested.

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I like my Suunto KB-14 compass. It is extremely durable, with no hinges, wires, mirrors, sharp edges, or complicated reading techniques, - a very sturdy aluminum case with a top and a side window. You hold the unit up to your eye and as you line up the image of the hairline with your target, through the window on the edge of the unit you can read the bearing that has markings to ½ degree. The one I bought many years ago has no declination adjustment, but I see they have models with that now.

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I have 2 compasses but the one I use most often is a Suunto MC-1 which I bought about 25 years ago for around $45. It is probably obsolete by now. It has a sighting mirror and adjustable declination. I made a little card from white plastic to hold under the dial... this provides more contrast when trying to line up the needle. I also have a Brunton Sightmaster SM360SA which is a hand-bearing compass, also about $50. It is not equipped to deal with declination but instead gives you an easy to read magnetic bearing of whatever you're sighting on. It uses a kind of split image and you can read the bearing numbers while sighting then add/subtract the declination for your area if you know it. Both have their benefits but I find the hand bearing compass really easy to sight with whereas the Suunto is well suited for map use. My advice is spend the money and get something you'll use and be happy with for 40+ years rather than buy something cheap and wish it worked better.

Edited by Ed56
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