When I compare the Delorme Earthmate PN30 and the Delorme Earthmate PN40 on the REI website they look like they are virtually identical, except the PN 30 has expandable memory. This looks it would be a plus. Yet the PN40 is more expensive and a newer model.

Can you provide any insight about why you would purchase one over the other? In the Pisgah area of the NC mountains there are miles of criss cross trails with no markers. Without a GPS or knowing how to read a compass you are pretty much up the creek.

What kind of GPS do you use?

Nathanael’s Answer

Hi Susan,

Thank you for your question.

Best GPS Hiking Unit - DeLotme EarthmateActually, both the Delorme Earthmate PN30 and the PN40 have expandable memory. The two units are identical, except that the PN-40 adds a tri-axial electronic compass and a barometric altimeter.

What does this mean? An electronic compass will give you a bearing even when you’re standing still. (All hiking GPS devices can display your bearing when you are in motion.)

A barometric altimeter gives your altitude based on the barometric pressure–a more accurate measurement than most handheld GPS units, which calculate altitude from satellite signals.

Calculating altitude from satellite signals is much less precise than calculating latitude and longitude; thus, GPS devices which lack a barometric altimeter give altitude readings that can be off by hundreds of feet.

Having a more accurate altitude measurement can help you place your location on a topographic map more precisely.

Also, a barometric altimeter can help you predict the weather. When the pressure falls rapidly, this usually indicates that a storm is coming.

Now, in my opinion these extra features fall into the “nice to have (if you can afford it), but not essential” category.

They make navigation a little bit easier, a little more accurate, but they won’t make the difference between getting lost or finding your way if you know how to use your GPS device, map, and compass. (And you should always carry all three.)

So it really comes down to how much off-trail navigation you intend to be doing, and how important it is to have the most accurate readings. (Like if you want bragging rights for how high you’ve gone.)

Both the DeLorme Earthmate PN-30 and the DeLorme Earthmate PN-40 are excellent GPS units. The real value, I think, is in the included topo and street map software and the $40 coupon for map downloads.

I also like the 360 degree raster rotation, meaning that the map rotates with you–objects on your right are on the map’s right, too.

And the units have fast processors for rapid map redrawing–no waiting for the map to load a new section.

As for me, the only GPS I own right now is a SPOT GPS
for tracking and emergency rescue signaling. Being a husband and father means I have to take hiking safety very seriously.

I had a Magellan eXplorist 300, but my brother lost it in the wilderness last fall when I loaned it to him for a backpacking trip. 🙁

That unit had a basic electronic compass (not as nice as the PN-40) and a barometric altimeter. I never used the compass, and only rarely used the altimeter. But I usually stick to trails, so they weren’t very important to me.

For my next hiking GPS unit, I’m thinking about saving up for the soon-to-be-released (July 31, 2010) DeLorme Earthmate PN-60W Portable GPS Navigator with SPOT Satellite Communicator. I like the idea of having both units combined. We’ll have to wait and see how well it works, though.

Thanks again for taking the time to ask your question! I hope this information helps you make the best choice.


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