Compass use

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PADI Knight

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Location
Central Kentucky
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Wondering if my lensatic military compass can be used for underwater nav. Gets wet all the time on land use. The orginal instruction sheet in it's pouch says it's water proof but doesn't list to what depth. Any ex seals out there that know or has anyone else used one of these?
 
Yeah I think it is liquid filled. I had tried a search before posting but didn't get any hits so thought it had not been asked.
 
If it is a keepsake and has meaning to you I would not risk it. You can get a compass on e-bay for $35-$45 knowing it will take the depth.

If you count on it to get around town...well, you have other issues....:D
 
here is what I figured out after looking at a number of compasses.

On a dive compass the outside card is numbered clockwise, the same as any land compass for top down viewing. THe inside card is counter clockwise so if you view it via the side window pointing in the direction you are going course changes move in the correct direction. Showing the true course.

Now if you don't mind viewing only top down, Suunto stated in and e-mail to me that although they cannot guarentee there would not be any problems using land compasses under water should respond the exact same way.
 
Check the brand of your compass. If it is a Cammenga (the military lensatic used by U.S. forces) it IS NOT liquid filled. The Cammenga lensatic uses a copper induction dampening system instead of liquid. I have a Cammenga and use it for backpacking and land navigation.

There is no milspec on pressure or depth for the compass, so there is none given by the manufacturer. That said, Mike over at Cammenga has taken his lensatic down to 35 feet without any problems.

I've never tried using a lensatic underwater, so my skepticism may be entirely unfounded. I question the benefit of a lensatic--precision navigation--in most diving situation. Lensatics were (and are) used for directing long-distance artillery fire and cross-country navigation. In those applications, a degree off the mark means you miss a distant target or destination by several hundred feet, if not more. Under water, the distance to a destination is more often measured in feet or yards than miles. Also, in murky water, you can't sight on a target with a lensatic, so if you're picking a target to travel toward, there's no benefit.

On the other hand, if you're doing underwater cartography I suppose a lensatic would increase your accuracy if you pick out headings and distances on the surface using the lensatic, and then duplicate that pattern on the dive.
 
"if you pick out headings and distances on the surface using the lensatic, and then duplicate that pattern on the dive" Yep that's what I had in mind
 
Diving is too expensive a hobby, to bother about not buying a sepearate compass for underwater. It's one of the chepaest pieces of gear afterall.
 
doghouse:
here is what I figured out after looking at a number of compasses.

On a dive compass the outside card is numbered clockwise, the same as any land compass for top down viewing. THe inside card is counter clockwise so if you view it via the side window pointing in the direction you are going course changes move in the correct direction. Showing the true course.

Now if you don't mind viewing only top down, Suunto stated in and e-mail to me that although they cannot guarentee there would not be any problems using land compasses under water should respond the exact same way.

I have used the cheap Suunto hikers compass underwater for years with no problems, less than $10 at Wal Mart.
 
captain:
I have used the cheap Suunto hikers compass underwater for years with no problems, less than $10 at Wal Mart.
I've used both Walmart and Silva hikers compasses underwater and on my sailing dinghy. On the dinghy, where they are wet down with saltwater daily, the copper(?) spring holding the bezel to corrode, making it very difficult or impossible to rotate the bezel. If you rinsed it off after diving, this shouldn't be a problem.

Obviously, the lensmatic or hiking compasses won't be as tolerant of tilt angle as are diving compasses, but a good compass user always checks to be sure the card is swinging freely when taking a bearing.
 
https://www.shearwater.com/products/peregrine/

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