Lensatic compass

[29palms]

Has anyone ever sailed just utilizing a Lensatic compass? Or just a hand held compass? I find a lensatic compass very useful and accurate. I like the precision of it. Of course, I'm partial to the military lensatic compass. I like to use them when traveling, and even checking out the direction the plane is flying. I know GPS has just about ruled out the compass somewhat absolete.

[goboatingnow]

Not much use where a typical cockpit compasses is on a sailing boat. IN handhend form I prefer a prismatic compasses like the Vion Vion MiNi 2000 Handbearing Compass, good nighttime illumination, easy to read and robust. I have found the typical military style lensatic compasses not to damped enough for sailing and not robust enough.

Dave

[DaleM]

I have used them for smaller boats on inland waters. It is a compass that I can carry with me, it's cheap and I can get another one at Walmart.

While a larger compass at the helm should be more accurate, I found that on a small boat, the bouncing around makes any compass sort of a ballpark device. It gets me close enough that I can use my eyes to find out where I am.


Dale

[GrowleyMonster]

Indeed. If it is a liquid filled compass it could be of some use. A proper hand bearing compass has lots of uses. I sometimes use it to sight back up my wake, for determining my course through the water and therefore my leeway. Taking bearings, well, that's what it's made for. As a steering compass, kinda marginal but on a daysailer with no compass when you think you ought to have one, sure, better than nothing. I would strongly advise doing regular compass checks either on a range line or with amplitudes or azimuths, and not relying on any great level of accuracy when used in a different location on the boat. Your deviation table will only be good for the exact spot in the boat where you checked it. And your deviation WILL be significant!

Do I advise using one as the primary compass on an offshore passage? Absolutely not. A proper compass isn't going to put you in the poorhouse if owning the boat in the first place doesn't. Nice to have along, though.

[29palms]

Like you say, better than nothing. I took a course via map reading once, and the lensatic compas had alot of interesting capabilities. Of course, more for land use. A military LC is liquid filled. They aren't that cheap. Brand new like 120 bucks or so. You can get close versions at any army navy surplus stores for like 12 bucks. They look exactly the same only made in China. They seem to work well. But I'll agree, its better use for treking on land after you make your landfall on your vessel.

[29palms]

Originally Posted by goboatingnow

Not much use where a typical cockpit compasses is on a sailing boat. IN handhend form I prefer a prismatic compasses like the Vion Vion MiNi 2000 Handbearing Compass, good nighttime illumination, easy to read and robust. I have found the typical military style lensatic compasses not to damped enough for sailing and not robust enough.

Dave

Very cool looking compass. I have a SUUNTO compass. I have that one that flips with the mirror here is a cool link.

suunto compass - Bing Images#

[S/V Alchemy]

I like that Vion. Nice bit of gear.

I have two boats: a F/G 33 footer with a Contest compass in the bulkhead, and a steel 41 footer with a compensated Ritchie Globemaster at the pilothouse helm and a fluxgate nearby. All are "swung" properly. On both, however, I use a hand-held bearing compass (Davis, I think) from the cockpit. As I can reliably stand in the same spot (at the end of the tiller or at the outside helm on the steel boat), I can take "good enough" bearings (within 5 degrees) to shore features/day marks. I have to have the bearing compass about 65 inches off the steel deck to overcome its deviational effects, but the rest is the same.

You may find useful my fair-weather nav trick of placing bits of tape along the toe rail at points 45 degrees, 60 degrees and 90 degrees to my eye, relative to the centerline of the boat (and on both port and stb.). You line up the shore feature at 45 degrees and note the time. At 90 degrees or "abaft", you note the time. Throw in the actual degree readings for comparisions.

Five minutes of light math and a paper chart later, you can determine your average speed and/or distance off. It's basic pilotage, but I find I can dispense with the bearing compass entirely and just use the watch and get pretty impressive accuracy "by eye" using this method of pre-chosen angles.

Of course, you could use a GPS, follow a depth contour or even a sextant flipped on its side (far better than a bearing compass...), but where's the fun in that?

[cal40john]

Originally Posted by 29palms

Very cool looking compass. I have a SUUNTO compass. I have that one that flips with the mirror here is a cool link.

suunto compass - Bing Images#

The advantage of the prismatic hockey puck compass is there are no sights and it doesn't need them. The prism allows you to line up the compass degree mark with what you are sighting on and you can rotate the compass through the range that the degree marks are visible in the prism and the correct degree line stays on what you are sighting on. This is an advantage over a compass where you look at sights then transfer your attention to the compass card. Davis makes a handbearing compass that you can freeze with a button after you have your sights lined up, which is a step closer to the hockey puck.

Mine is one they don't make anymore that I wish I could get another. There is a tritium capsule that lights up the phosphors for 20 some years. With the current models you have to shine a flashlight on it to activate the phosphors.

John

[mrm]

Originally Posted by cal40john

Mine is one they don't make anymore that I wish I could get another. There is a tritium capsule that lights up the phosphors for 20 some years. With the current models you have to shine a flashlight on it to activate the phosphors.

John

John,

Tritium capsules are available as a component for torchlight hobbyists (sort of a practical jewellery for a torchlight) so if you need to replace one, that is a place to look.

Marius

[29palms]

Originally Posted by cal40john

The advantage of the prismatic hockey puck compass is there are no sights and it doesn't need them. The prism allows you to line up the compass degree mark with what you are sighting on and you can rotate the compass through the range that the degree marks are visible in the prism and the correct degree line stays on what you are sighting on. This is an advantage over a compass where you look at sights then transfer your attention to the compass card. Davis makes a handbearing compass that you can freeze with a button after you have your sights lined up, which is a step closer to the hockey puck.

Mine is one they don't make anymore that I wish I could get another. There is a tritium capsule that lights up the phosphors for 20 some years. With the current models you have to shine a flashlight on it to activate the phosphors.

John

Man, great but that's an expensive compass. (Over 100 bucks.) Is it worth that much more in convenience? The walmart brand version I believe was what? 3 bucks? Still can do the same thing minus lighting up at night? The degree markings do light up or glow in the dark. I know its cheezy but really. My Suunto I paid 40 bucks for it, but I didn't like it any better than my chinese military duplicate of a lensatic compass. The Suunto I have can take readings to estimate height of a mountain. Just got to know the distance to it. It can read slope in degrees. The real military lensatic compass, I believe can buy for roughly 75-80 bucks is titanium and pretty solid, can take a good beating. I think its made by CAGNON. My Suunto is the one I have now, pretty handy when I travel. Just nice to take to an island like Cozumel, and shoot some azimuths around. But really, a three dollar one probably gets same results.

[cal40john]

Originally Posted by 29palms

Man, great but that's an expensive compass. (Over 100 bucks.) Is it worth that much more in convenience? The walmart brand version I believe was what? 3 bucks? Still can do the same thing minus lighting up at night? The degree markings do light up or glow in the dark. I know its cheezy but really. My Suunto I paid 40 bucks for it, but I didn't like it any better than my chinese military duplicate of a lensatic compass. The Suunto I have can take readings to estimate height of a mountain. Just got to know the distance to it. It can read slope in degrees. The real military lensatic compass, I believe can buy for roughly 75-80 bucks is titanium and pretty solid, can take a good beating. I think its made by CAGNON. My Suunto is the one I have now, pretty handy when I travel. Just nice to take to an island like Cozumel, and shoot some azimuths around. But really, a three dollar one probably gets same results.

The light isn't the important part. The prism requires no sights. On a rolling pitching boat taking a bearing with most compasses with a sight, you line up the sights, the boat moves, you look at the compass card, and you have an inaccurate bearing.

With a prism compass you line up the degree line from the compass card on your object and you're done.

An example:
K&R Alpin PRO Baseplate Sighting Compass

Click on the inset picture to see that you see the compass card is what you line up with your object.

[jackdale]

John

+1

I have an old mini Morin that I use in daylight (dead tritium cell). At night I use a Plastimo that looks like something Captain Kirk would pilot. I leave it under a light all day and it works well during the night. It will recharge under the nav light on the chart table.

I had a Silva and got rid of it.

I tried an Brunton electronic one and gave up on it.

My inexpensive Optisan binoculars has a compass, but I still like my two prismatics - the Morin being my favourite. It settles down fast and us easy to read.

[29palms]

Originally Posted by cal40john

The light isn't the important part. The prism requires no sights. On a rolling pitching boat taking a bearing with most compasses with a sight, you line up the sights, the boat moves, you look at the compass card, and you have an inaccurate bearing.

With a prism compass you line up the degree line from the compass card on your object and you're done.

An example:
K&R Alpin PRO Baseplate Sighting Compass

Click on the inset picture to see that you see the compass card is what you line up with your object.

Sorry, I still don't get how this compass works. On the compass I have, I use the sight marker to line up to the destination I want to go, then I turn the dial so that the needle goes in between these red lines in an arrow that always points to the north on the dial, then take my reading. Example. I am facing SE, line up my site marker to the SE, then turn the dial so that the needle goes in between the red ARROW which has two lines, hollow in the middle that the needle goes in between as I turn the dial that points to the NORTH and take my reading off the site marker.

From what I gather of your compass, you don't turn any dials but rather, the compass card changes along with the dial? How does this work again? Explain PRISM. My compass may have one, or not, but my compass has a mirror. The way the mirror works is as you look through the sight marker, you bring the flipped mirror down to about 45 degrees and you can see the dial as you turn it, but you are looking at the dial somewhat backwards, but its legible. So you are zeroing pretty accurately. It's not like a lensatic compass but pretty close. With a lensatic, you don't use a mirror. You move the magnifying eyepiece down to 45 degrees where you can view the sight and then look down at the eypiece to catch your reading on the dial.

[cal40john]

Originally Posted by 29palms

Sorry, I still don't get how this compass works. On the compass I have, I use the sight marker to line up to the destination I want to go, then I turn the dial so that the needle goes in between these red lines in an arrow that always points to the north on the dial, then take my reading. Example. I am facing SE, line up my site marker to the SE, then turn the dial so that the needle goes in between the red ARROW which has two lines, hollow in the middle that the needle goes in between as I turn the dial that points to the NORTH and take my reading off the site marker.

From what I gather of your compass, you don't turn any dials but rather, the compass card changes along with the dial? How does this work again? Explain PRISM. My compass may have one, or not, but my compass has a mirror. The way the mirror works is as you look through the sight marker, you bring the flipped mirror down to about 45 degrees and you can see the dial as you turn it, but you are looking at the dial somewhat backwards, but its legible. So you are zeroing pretty accurately. It's not like a lensatic compass but pretty close. With a lensatic, you don't use a mirror. You move the magnifying eyepiece down to 45 degrees where you can view the sight and then look down at the eypiece to catch your reading on the dial.

The prism brings a view of the compass card up vertical. When you look at your object you will see the degree mark of your compass card under your object.

I have a Suunto mirror compass for hiking. Even with the mirror you have to shift your attention from the sights to the mirror, when hiking you're not spinning around when getting a bearing, with a boat you are.

Above you stated for the lensatic "view the sight and then look down". This is where on a boat from the time you view the sight and the time you look down the boat has moved making the number you read the wrong one. On a hockey puck you are seeing the degree mark of the compass card and the object being sighted at the same time.

I've never seen a hockey puck style compass for less than $80 and I'd be surprised if you could find one at Walmart.

OK, I've found a video showing a real hockey puck being used:

Iris 50 Hand Bearing Compass - YouTube

From here a better description:
The West Advisor: Hand Bearing Compasses

A better choice is a hockey puck style compass with an infinity prism that is held up to your cheek, and lets you sight across the top of a small prism. When you are focusing on the object in the distance, the prism projects the bearing into your field of vision so you don't have to shift your eyes. Object and bearing are in focus at the same time, which is a tremendous asset for taking accurate bearings in rough conditions.


One of the companies made a compass that looks like a hockey puck compass for about $40, but it is actually a compass that uses sights. I think it is this one: Ritchie Sportabout Compass

[GrowleyMonster]

Like this one?
Mini 2000 Compass | Compasses | Celestaire, Inc.