Surface compass underwater

[MarkH]

Here's a question: I was wondering why I should spend 100$ or more on a dive compass when you can buy those orienteering-type compasses in an outdoors store for 10 dollars or so. They are fluid-filled and the housings are sealed and seem pretty thick. Has anyone tried these. Am I an idiot?

 

[Diver0001]

Here's a question: I was wondering why I should spend 100$ or more on a dive compass when you can buy those orienteering-type compasses in an outdoors store for 10 dollars or so. They are fluid-filled and the housings are sealed and seem pretty thick. Has anyone tried these. Am I an idiot?

in a word..... metal parts.

For example, most of them have a little metal ball-bearing under the bezel....if it's not stainless steel then.....you get the picture. Some of them may be suitable depending on the materials used.

R..

 

[goatboy_k]

i think he was talking about the clear plastic ones that you can see the map through. I think it would work pretty good as ive seen several of those survey slates that have compasses that look just like those. I know that the mapping compass's are nearly bombproof that ive used even in the 10 dollar range. the only thing is most of those don't have the degree's on the side or a side window, so you'd have to look down to nav, where as most dive compass's you can hold out front and use the side window.

kurt

 

[hantzu701]

If u shop around, U can get a good dive compass such as the Suunto SK7 for $50-$60 which isn't much more than a real orienteering compass such as the Silva Ranger.

I have a suunto SK7. I also have a $10 Silva compass which I picked up at Walmart which I have zip-tied to a DIY slate on a retractor. I have had the compass to 65ft in freshwater with no leaks.

I use the SK7 for underwater navigation. It sits on my left wrist. This allows me to form a stable "h" with my arms while I am in motion and get a quick, reliable reading. Good vis for me is 10ft and less, so I rely heavily on my uw compass. My tolerances for underwater nav are pretty narrow.

I use the $10 Silva compass for underwater surveying. I have not used the $10 compass for uw nav, but I suppose that you could make it work - drill holes and bungie it around your wrist. But, unlike a dive specific compass, the needle on any land compass needs to be kept ABSOLUTELY flat. Keep in mind that you'll need to slow down and get a stable platform in order to get a good reading. This may or may not work for you.

Easier reading = less stress = more fun for diving.

If ur planning to dive for a long time, save your $10 and get a real dive compass. Think of it as a one-time expense. UW nav is such an important skill that everyone should know how to do. Even if you just dive in the tropics, it's nice to be able to get back to the boat on your own without sending for a chase boat.

 

[SDAnderson]

Is there actually somebody out there trying to charge $100 for a compass?

Use whatever compass works best - and the need for an expensive underwater compass is far from certain. I like my wrist mount, but that's just me. A simple liquid filled non-metallic compass should work just fine.

Don't believe me? Here's a link to a photo of George Irvine's compass.

Here's a $10 compass from a name we all know and love.

 

[Meng_Tze]

I run a Silva 9020 'Global compass' on my wrist. Is a bit getting used to when taking bearing because it needs to be somewhat flat (as someone mentioned before), but it works a treat and is small, accurate and cheap.

 

[hantzu701]

Is there actually somebody out there trying to charge $100 for a compass?

Use whatever compass works best - and the need for an expensive underwater compass is far from certain. I like my wrist mount, but that's just me. A simple liquid filled non-metallic compass should work just fine.

Don't believe me? Here's a link to a photo of George Irvine's compass.

Here's a $10 compass from a name we all know and love.

ummm... I disagree w/ ur conclusion.

George Irvine's compass in the pic is a Suunto M3, which is a really nice compass and runs about $30. In addition, he is using it for uw survey work, not uw nav which is the primary reason for an uw compass.

Note: The NSS Cave diving Manual recommends land compasses over dive compasses for uw survey work because land compasses are usually calibrated in 2 degree increments verses 5 degree for dive compasses.

When I shopped around at LDS's in Chicago, the price point seemed to be about $85 for a dive compass. Didn't seem to matter which brand. Leisurepro has the SK7 for $60, but then you need to add shipping.

Note that you can have the most expensive compass on the market won't help you if you don't know how to use it. Diving underwater is not like hiking a well-worn trail. Glance at your compass from time to time, and get 3-4 min snapshots of your status. A poor compass - eg. the scubapro compass for the Aladdin pro console, will make u really unhappy. Get the right equipment and you'll be happier for it.

 

[SDAnderson]

ummm... I disagree w/ ur conclusion.

Oh...the audacity!

Gear selection inevitably involve some compromises and the best solution isn't always the most expensive - that's what I was trying to say. Choosing a compass involves some choices: mounting, inclination, graduation, declination, damping, materials, size, weight, money, etc.

For some, a highly accurate hand-held compass with an adjustible declination scale maybe what's needed. Others may want wrist mounted with a sighting window and the ability to function while off level. Those that choose a console mount typically give up most of the remaining decisions, including features, availability and price.

Everyone should find out what the options are and buy what they need - and there are a lot of choices outside of the local dive shop. Here's a link to the Suunto USA compass page. See what all the fuss is about.

 

[Diver0001]

I run a Silva 9020 'Global compass' on my wrist. Is a bit getting used to when taking bearing because it needs to be somewhat flat (as someone mentioned before), but it works a treat and is small, accurate and cheap.

This is an excellent point. Most land compasses can't be tilted very much. Under water compasses are often made to take tilt up to something like 30%. If a compass has to be held flat to be useful then it will be very difficult to use under water.

R..

 

[pipedope]

While a land compass will work under water (as long as it is liquid filled) it is better suited for surveying than navigation.
If you are trying to navigate in low vis a wrist mount diving compass is simply MUCH easier to use.

I have also used a land compass as a handbearing compass while navigating a sailboat but it was more work than a proper handbearing compass.

Using a land compass on land is easy, you are stationary and it is easy to hold the compass level, get things lined up and take your reading.
In a dynamic environment, like on a boat or underwater, you rarely have the ability to stay stationary, currents and surge will make using the land compass much harder than on land.

More often than not, it is worth investing in the best tool for the job.

Don't even ask me how many compasses I own.