Compass and Backup Dive Computer Setup Questions

[cashew]

Hi everyone,

I am a total newbie scuba-er. I am in the middle of my PADI certification right now, and will be going for my open water dives later this month.

By way of background, I have a Sherwood Amphos Air-Integrated dive computer, as well as a backup analog SPG. When I was doing my confined pool dives, I noticed that my Amphos would sometimes blank out as if it was no longer receiving transmissions from the AI transmitter. Also, during the out of air test (where the instructor turns off your air tank), the Amphos sometimes was not sampling my air pressure fast enough to show a change in the pressure before I was out of air. (The analog SPG did fine though). I'm not exactly sure what is causing these issues, though.

With that in mind, I had a few questions regarding compass setup and a backup dive computer. Currently, I need a compass but I am not sure if I want to have a separate wrist-mounted compass or a retractable compass. Do folks have any recommendations as to which setup is preferable? (I am awfully near-sighted, if that matters at all, and wear contacts while diving).

I am also considering getting a full backup dive computer rather than just the analog SPG, as I am not sure whether the Amphos stops functioning as a dive computer when it can't register how much air I have via the transmitter (I think it still continues to log dive data, but not 100% sure). I saw that some dive computers have integrated (analog) compasses as well - would I be better off getting a combined unit, or keeping the compass separate? Also, does your backup dive computer need to use the same algorithm as your primary dive computer, as it seems that different algorithms will give different results/data/times?

Thanks in advance for all of your expertise!

 

[LeadTurn_SD]

Hi cashew,

I'm a big fan of wrist mounted compasses. The Suunto SK-7 is the best I've found:

Suunto SK8 Wrist Compass 186570

As far as a backup computer I'd recommend using one with the same algorithm if possible, but as long as you are taking BOTH on the dive, if your primary fails you should be able to seamlessly switch to your backup and be "ok" for a standard recreational dive. It may give you several minutes less (or more?) bottom time depending on its level of conservatism relative to your primary computer, but will still keep you within NDL's.

I'm not a big fan of retractors.

Best wishes.

 

[Zeagle Eagle]

What LeadTurn said, except I am a big fan of console on a retractor.

 

[cashew]

I'm a big fan of wrist mounted compasses. The Suunto SK-7 is the best I've found:

Suunto SK8 Wrist Compass 186570

Thanks. I saw that you mentioned the SK-7 but linked to the SK8. Is there a significant difference between the two models?

I'm not a big fan of retractors.

Can you elaborate more on this point? Retractor as in, attached to a console? Or a stand-alone compass?

---------- Post added August 10th, 2015 at 07:51 PM ----------

What LeadTurn said, except I am a big fan of console on a retractor.

You mean like the dive computers that have the compass at the top (and pressure gauge on the backside), with the console underneath? Do you have any recommendations for a console with compass?

 

[LowDrag]

I put my transmitter on the side of my first stage that lines up with my wrist mounted computer. I have not had a lost signal up to this point. As for the compass, I am going to buy a compass that I can mount to a slate. You can write notes on it, such as directions and it can help steady your compass while you are holding it.

Something like this https://www.divegearexpress.com/tech-compass

 

[LeadTurn_SD]

Thanks. I saw that you mentioned the SK-7 but linked to the SK8. Is there a significant difference between the two models?



Can you elaborate more on this point? Retractor as in, attached to a console? Or a stand-alone compass?

Hi,

I actually did not know that the SK-8 had replaced the SK-7, but that appears to be the case! From what I briefly read, the SK-8 is an improved SK-7. Same dimensions, just improved magnets and such I think.

Regarding consoles and wrist gauges and retractors: This is personal preference territory. I prefer my compass, computer and old school dive watch on my wrist. I do not like consoles. I do not like retractors. But many others love them.

I do use a simple "brass and glass" spg.

I find mid-water navigation and depth-holding (mid-water meaning limited visual references with bottom, surface, etc.) easier in the standard swimming position with all important gauges (depth, time, direction) on my wrist. I can swim with my arms held slightly forward as an aid to horizontal trim (think Superman flying, but with one hand clasping the opposite wrist) and easily glance at my compass and computer without having to look down and break trim or unconsciously change direction by looking away from my intended course.

Your mileage may vary. This is just what I have come to prefer over the years.

Best wishes.

 

[cashew]

I put my transmitter on the side of my first stage that lines up with my wrist mounted computer. I have not had a lost signal up to this point. As for the compass, I am going to buy a compass that I can mount to a slate. You can write notes on it, such as directions and it can help steady your compass while you are holding it.

Something like this https://www.divegearexpress.com/tech-compass

Interesting. I have the transmitter mounted on the right side, but wear the computer on my left wrist. Maybe I will try swapping the two to see if that improves reception.

On the compass point, how do you mount a bungee compass to a slate?

 

[Macan]

I use a Suunto SK-6 direct reading compass on every dive. It's a gem . Compass on the left wrist. Computer on the right wrist. This is the tried and tested Tec configuration that works so well and keeps everything streamlined.

On land, I transfer my wrist computer to my left wrist. You get use to it.

 

[archer1960]

For my training nav dives I had a wrist compass, but I thought I would prefer to have the compass on the console, so that's what I bought (without actually trying it) when I got my own equipment. But I discovered after a few dives, that I much prefer having it on my wrist, so just bought the Suunto SK8. I still have the compass on the console as a backup compass, and the console also has a depth gauge on it so it is a backup for my wrist computer. And I wear a regular 200m waterproof watch on my right wrist, so I have a backup timer as well. The only instrument I don't have a backup for is the analog SPG in my console, and those are pretty reliable...

 

[Storker]

Compass on the left wrist. Computer on the right wrist. This is the tried and tested Tec configuration that works so well and keeps everything streamlined.

I think I understand the reasoning behind that config, and it's sound. However, if you're night diving, it requires a can light on a Goodman handle, or a loose torch. I use a SOLA as my primary light, and it's a bit awkward (to say the least) to switch that to my right hand to be able to look at a left wrist mounted compass. Since I don't use a scooter - which is, as far as I can understand, the primary reason for keeping the compass on your left wrist - I'm wearing both my compass and my backup computer on my right wrist/forearm, the left forearm real estate being occupied by my wrist slate.

As LeadTurn_SD said, this is personal preference territory (unless you're taking a GUE class ), so IMO you should spend a few dives experimenting to find out what works best for you. Although I have a very strong preference for a bungee mounted compass and believe that that's the only way to go.

BTW, when you get older and presbyopia sets in, you don't want a console mounted compass. Just sayin'...