SCUBA Compass

mugwump · 01-16-2007, 17:40

A story that roundabout leads to a question.

Wife's sisters <shudder> came into town over the holidays, so the daughter and I skipped off wall-diving in Grand Turk for a week. Dove all week with a Playboy model

("What a coincidence! I like scuba diving and long walks on the beach TOO!"), and two days with a very fat Belgian

. He saw me checking my daughter's safety gear (folded snorkel, strobe, sausage and spool, a good mirror, flashlight, whistle, 1-pint Platypus w/ fresh water, bandanna) and said "You Americanzzzzs. So much! You even waste energy when yeeeou play." Well, that's rich coming from a lardgut who needs 22 (!) pounds of lead to sink his skinny ass. Screw him, it all fits in one pocket. I may be paranoid but we've drifted for seven hours off Tobago playing "Open Water" and all that stuff falls under "lessons learned."

Well, daughter and I go seven coral cuts south against the current and seven cuts back. Beautiful dive. Turn right, find the mooring block, hmmm, no cable. We do our hang and come up to lardgut and spouse thrashing and moaning. No boat. Little tiny speck skidding away -- broke its mooring (very stiff trades blowing, very small boat, old moring cable) and took off. ("Can you say 'Irony?' Sure, I knew you could.") The divemaster, who can't stand the Belgian, says "Mon, you'd better swim in and get a boat. I don't want to drift past the north end of the island -- there are a lot of bullsharks there this time of year." LOL, you should have seen Belgian's face. I hand over my strobe, sausage and mirror to the divemaster and he, Hottie, and the Belgians stay put while daughter and I swim for shore (it was only about a mile, but much more than the Belgians could make). Made it about halfway when an eagle-eyed fisherman on shore saw the sausage I was towing and picked us up (big tip and nice steak dinner for Mr. Fisherman and his wife). The current was running pretty good out past the wall where they were and they'd drifted a piece but we saw their sausage and picked them up pretty quickly.

OK, end of story and now the query: What's a good SCUBA compass that is tolerant of less-than-perfect level? When we were swimming back there was some fairly decent swell and my compass needle constantly got hung up. Went northeast for a spell when I thought I was going east. I remember a spherical dive compass on a chain back in the day that couldn't hang up but I can't find one on the 'net.

Any recommendations gratefully accepted.

x SF med · 01-16-2007, 18:50

Mug-
Have you thought of one of the digital, sealed dive compasses? they can't hang up. Just a thought.

http://www aqualung.com/products/d9.html (add the dot after www to make it work)

mugwump · 01-16-2007, 20:29

Quote:

Originally Posted by x SF med

Mug-
Have you thought of one of the digital, sealed dive compasses? they can't hang up. Just a thought.

http://www aqualung.com/products/d9.html (add the dot after www to make it work)

No I didn't. Thanks for the idea, I'll look into them.

Snaquebite · 01-16-2007, 20:56

Suunto makes good stuff

http://www.suunto.com/suunto/main/ar...=1132533105448

mugwump · 01-16-2007, 21:09

Quote:

Originally Posted by Snaquebite

Suunto makes good stuff

http://www.suunto.com/suunto/main/ar...=1132533105448

Thanks. The SK-7 looks good: "The superior SK-7 has an exceptional tilt potential of +/-30 degrees, which is 2-3 times larger than in conventional diving compasses. "

Sdiver · 01-16-2007, 22:04

Yes the SK/7 from Suunto is a great digital compass. But don't fall into the trap of, just because you have the latest "bling", that you don't forget and stick with the basics.

Mug,
Not pointing a finger at you, this is just a general refresher for any and all who use a compass, whether U/W or Above Water/snorkeling.

When using a compass above water, while snorkeling or doing a surface swim...

1) Look at the conditions of the water and how and which direction the wind is blowing. Is there much of a chop? Can you tell which way the current is going? Can you see the surf breaking? If not, this will be something that you will want to take into accounting, the closer you get to shore.

2) Pick out a very distinguishable land mark. (I used to tell my students to pick out two.) I say distinguishable, because hotels/condos/buildings can all look the same the closer you get to shore. (that is, if you are doing pin point surface nav.) If you aren't doing pin-point surface nav, and are just attempting to get to shore, it is still advisable to pick out a land mark.

3) Once you have you land mark picked out, align your compass heading with that land mark. Mark it/lock it in, depending on which compass you're using.

4) Begin your swim on your heading.

5) After a set amount of time, whether you are using a watch or kick cycles to mark your time, after a set amount of time, stop where you are. Check your heading on your compass to the land mark(s) that you have picked out. Adjust accordingly. Repeat this process several times. Don't just trust in one or two or even three readings. Check, check, check, and re-check, over and over.

6) As you approach the shore, what are the conditions of the surf. Can you see any foaming water away from the beach? This could denote a sand bar or two. If so, there is most likely a rip tide/current between those sand bars. How are the waves "crashing" on shore? Adjust accordingly.

Remember, the best way to use a compass while on scuba/rebreather or even on snorkel is under water, and close to the bottom. You don't have to tend with the wind affecting you, and the currents are somewhat less towards the water's floor.

**Peregrino** · 01-16-2007, 22:37

SDiver - Good advice, especially the part about staying close to the bottom in shallow(er) water. Course the last time I swam >1 mile underwater it wasn't with recreational gear either. (Yes - I'm jerking your chain

) I quit doing MILSPEC nav swims a long time ago. My preferred method for an extended surface swim is to shoot an azimuth, convert to a reciprocal heading, roll over on my back, put the compass on my chest, and read the heading through the sight glass/window. All your other steps are the same.

MW - I'll be checking out the Suunto too. Personally I use SCUBAPRO and Aqualung wrist compasses and don't have the problems with them that many people do with console mounted compasses. That and the "swim backwards" technique isn't as susceptible to needle/card lock. NTM I HATE snorkels and will avoid using them whenever possible. FWIW - Peregrino

**Pete** · 01-17-2007, 05:20

Quote:

Originally Posted by Peregrino

.... My preferred method for an extended surface swim is to shoot an azimuth, convert to a reciprocal heading, roll over on my back, put the compass on my chest, and read the heading through the sight glass/window. ..... NTM I HATE snorkels and will avoid using them whenever possible. FWIW - Peregrino

Ditto to Peregrino also;

If the air runs out you are forced to the surface. Very relaxing to roll over on your back for extened swims. Keeps your face out of the water also.

Pete

mugwump · 01-17-2007, 07:54

"My preferred method for an extended surface swim is to shoot an azimuth, convert to a reciprocal heading, roll over on my back, put the compass on my chest, and read the heading through the sight glass/window. All your other steps are the same."

D'Oh! What a great method -- should have known that. The part about hugging the bottom I knew. Daughter had 1700 and I had 1000 psi left and we were saving the for the approach and the shore break, which wasn't much as it turned out. My nav skills underwater are decent if there are features but nav on long swims is obviously weak - I was more a down and up diver before. I need to spend some time on that. I know about adjusting for current which is why I was upset at the ENE heading when I really thought I was on a ESE.

I agree about snorkels, generally useless, but we once spent a very long day stranded off northern Tobago in pretty rough conditions. We couldn't ride high enough to breathe without <spit><head shake> every breath. I swore I wouldn't have to do that again (or not have something to shade my face - still looking for a really small roll-able hat). I have two old Dacor? rubber snorkels from about 1968 that can be folded into thirds and tied flat. They built to last in those days.

I'm actually thinking about getting a dive-able EPIRB w/ GPS if the daughter and I head off to the Pacific this summer. Seven hours of wondering if I'd killed my daughter left a pretty big impression on me.

x SF med · 01-17-2007, 08:04

Peregrino-
Danish Scout Swimmer School? Or plain old SF MarOps? I remember the days of freezing the young butt off on lovely little swims using that method, and dragging a sea anchor (loaded ruck, praying it's packed well) along too.

Mug-
I haven't used that Suunto D9 I linked you to, but I use a Suunto Mariner as a backup compass (3*) while sailing. I go for a primary of my rated magnetic marine compass, secondary is my Garmin (they are kind of interchangeable), and then my Suunto for quick checks from the deck when someone else is driving.

mugwump · 01-17-2007, 08:05

You'll like this Peregrino/Sdiver/Pete...

The divemaster and two Democrat lawyers from DC "dove" a small wreck on a ledge of the wall: 212 feet on air w/ single 80s. Basically a touch-and-go. They had 2 tanks (air) hung at 15' for deco for 3 people, that's all. Did it on the spur-of-the-moment. "It's OK, it's our first dive of the day."

mugwump · 01-17-2007, 08:09

Quote:

Originally Posted by Sdiver

Mug,
Not pointing a finger at you, this is just a general refresher for any and all who use a compass, whether U/W or Above Water/snorkeling.

Point away, it's well-deserved. I used to be pretty good at deco theory but my nav skills could really use some work. Thanks for the refresher. Funny how I fell into a trap thinking good at one thing = good at all things. I usually don't do that.

mugwump · 01-17-2007, 08:37

I'm just really disappointed that a QP hasn't asked to see pictures of the Hottie -- I'm pretty sure Daughter took some.

x SF med · 01-17-2007, 08:39

Ok, I'll bite...... Pics or it never happened!!

(all better now? Remember, this is a family site.)

82ndtrooper · 01-17-2007, 10:43

Quote:

Originally Posted by mugwump

Thanks. The SK-7 looks good: "The superior SK-7 has an exceptional tilt potential of +/-30 degrees, which is 2-3 times larger than in conventional diving compasses. "

Ya beat me to the punch ! This is the only compass I have ever owned for diving. Yes, +/- 30 degree tilt. SK-7. Then again I still use the old tried and true Aqualung Rocket Fin I also.

http://www.suunto.com