JOE, I could not find an option on that site to select the area of the USA for which the compass is compensated ( East, Central, or West). You are correct that the compass can be returned indefinitely for recalibration ($3.00 fee), but I'd like to at least begin with one that is compensated for my area. TruNord makes a fine product. [color:"red"] [/color]

When I was at Smokey Mountain Knife Works a couple of months ago I got to look at about a dozen of the new Marbles liquid filled compasses and noted that they all had a unique and personal idea of which direction North was. I was checking them against my Silva Type #27 that I modified to wear around my neck. There are liquid filled compasses that I have used with out problems but I don’t think Marbles makes one yet

I think Marbles must be relying on their "legendary" status too much. Teddy Roosevelt supposedly used them. Well if T.R. had used one of these new ones we might be reading about his charge DOWN San Juan Hill. <img src="/images/graemlins/grin.gif" alt="" />

I just bought a Tru-Nord zipper-pull and a pin-on.

Regards, Vince

On his old web sight it said that your compass would be balanced for your mailing address unless you asked for something different. I have not found it on his sight since he put the new page together but I am sure he still sets them for your address unless you spec something else for him.

I got my True Nord compass yesterday and let me just say I was very impressed. It's as accurate as any other compass I own and I own a few real nice ones. It's my new PSK compass now. For the record it was not calibrated to the declination angle of my mailing address and it in fact points to magnetic north but it did come with a card that said that I could send it in with $3 for return shipping and they would set it to any declination angle in the USA or Canada for me free of charge. Where I live true north and magnetic north aren't all that different though so I won't be worrying about it.

Brian,
If it's not too much trouble, would you post a couple of pics of your Tru-Nord compass and the button compass that you keep in your Shadow III, side-by-side, with maybe a quarter in there for reference.

Thanks,
Hutch4545

I emailed Marbles, described the problem, and asked them what they would do about it. They replied that a new compass is on the way at no charge. They are not requiring the return of the old one or any other nonsense. When the replacement arrives I'll probably use it as a backup to my Tru Nord. Perhaps the quality problems were due to a bad lot. Time will tell. I am happy to see that their customer service is still up to par and for this they should be commended.

Regards, Vince

Brian,
If it's not too much trouble, would you post a couple of pics of your Tru-Nord compass and the button compass that you keep in your Shadow III, side-by-side, with maybe a quarter in there for size reference.

Thanks,
Hutch4545

I thought about this a while ago and think the explanation is this. The amount of torque the earth's magnetic field creates by pulling on the needle is proportional to the needle's length squared (R cross F integrated over the length of the needle, for you physics geeks) for a given type of magnetic material. So with a short needle you don't have much torque available. This torque must be enough to overcome the friction in the bearing. But the bearing friction is basically constant for a given type, or at worst proportional to the mass of the needle (i.e. its length).

That means to make a reliable small compass, you must either (a) get more torque by using an ultra-strong (i.e. expensive) magnetic material for the needle, and/or (b) use an ultra-low-friction precision (i.e. expensive) bearing to lower the amount of torque you need. It's far cheaper and simpler to just use a longer needle (lots of torque) and a cheap bearing.

If you're utterly cramped for space in a PSK, the idea of magnetizing a sewing needle sounds workable. You could put a tiny permanent magnet (nicely sticks to the side of your Altoids tin) in the kit, and rub the sewing needle against it (10-20 strokes all in the same direction) to magnetize it. Another idea is pry open a big cheap compass and remove the needle from it and just put the needle (permanent magnet) in the kit, suspending it from a thread or floating it to get a reading. I haven't tried either of these methods, so don't blame me if they don't work. I'd think either method would be a big pain if it's windy.

Rather than search endlessly for an ultra-small-diameter compass, maybe it's better to look for a larger diameter but ultra-thin compass. A compass could be made very thin and still have plenty of torque.

Paulr: Great analysis and extrapolation. Thanks for sharing. -- Bear