As a result of some discussions with my buddies after doing compass nav exercises, I ended up documenting some of the experiences with the compasses I have in my posession. Maybe somebody will find it useful.
Part 1: the compass that I so much wanted to like
ScubaPro FS2. On paper, looks great - good tilt tolerance, low profile, dual card markings for top and side reading - not like these Suuntos that have their bearings reversed when seen from the top... I got an OMS bungee wrist mount for it. It didn't fit very well though, but after some trimming and adding a shim and with some glue, it held the compass well enough. Annoying, but manageable.
Alas, not long after I noticed the compass was getting stuck. I bought a replacement capsule. It now has exactly the same issue.
For illustration, my reference:
ScubaPro attempt number 1:
ScubaPro attempt number 2:
If it's set more than ~50deg off, it will start moving, but below that it cannot overcome the friction of the card rotation.
But then, if it's wiggled or shaken or bounced or shaken, it is capable of pointing north:
It may work "well enough" when worn, because I probably don't keep my wrist very steady and it could settle correctly... but I don't trust it and at this point I consider it trash. And since it's the second one, I'm not willing to try anymore with a ScubaPro compass. If you have an FS2 and you think yours works fine, please test it and post the result. It might be that I was just very unlucky.
Part 2: is my compass accurate?
On a dive my buddies compass wasn't pointing north. Or mine wasn't. Either way, we disagreed on a heading. On the surface, we tested both by moving a piece of metal around the card. Sure enough, a Suunto SK8 was pointing to the piece of metal, while a Termos Pro (aka DGX Deluxe Pro) was pointing 30 degrees off. Maybe the needle under the card shifted, we thought. On a later examination, the reason why Termos was not pointing to the magnetic piece was because it has two parallel needles and the tip of one or the other needle will be drawn closest to the magnet. So it probably was fine and our issue can be blamed on either one of us not reading the compass correctly for whatever reason.
Part 3: responsiveness
While comparing the compasses, I noticed that the Suunto felt sluggish. My other compasses clearly moved around faster. Or were they? So, to compare, here's a video of all of them moving from 180 heading to a 0 heading:
From left to right that's:
Part 4: my personal opinions
So far I've used the Termos as my workhorse. It's easily readable, good tilt tolerance, responsive, robust. It is quite tall (high profile), but it hasn't bothered me so far. Occasionally it will fall off the center pin when in the gear bag, but a small bump puts it back on centerl and level. I haven't dived with Aqualung yet (I just bought it as a replacement for the FS2 that I'm throwing away), but I might like it too - it has a softer, more clicky bezel that is easier to operate, otherwise it seems to share all the properties . Time will tell.
Part 1: the compass that I so much wanted to like
ScubaPro FS2. On paper, looks great - good tilt tolerance, low profile, dual card markings for top and side reading - not like these Suuntos that have their bearings reversed when seen from the top... I got an OMS bungee wrist mount for it. It didn't fit very well though, but after some trimming and adding a shim and with some glue, it held the compass well enough. Annoying, but manageable.
Alas, not long after I noticed the compass was getting stuck. I bought a replacement capsule. It now has exactly the same issue.
For illustration, my reference:
ScubaPro attempt number 1:
ScubaPro attempt number 2:
If it's set more than ~50deg off, it will start moving, but below that it cannot overcome the friction of the card rotation.
But then, if it's wiggled or shaken or bounced or shaken, it is capable of pointing north:
It may work "well enough" when worn, because I probably don't keep my wrist very steady and it could settle correctly... but I don't trust it and at this point I consider it trash. And since it's the second one, I'm not willing to try anymore with a ScubaPro compass. If you have an FS2 and you think yours works fine, please test it and post the result. It might be that I was just very unlucky.
Part 2: is my compass accurate?
On a dive my buddies compass wasn't pointing north. Or mine wasn't. Either way, we disagreed on a heading. On the surface, we tested both by moving a piece of metal around the card. Sure enough, a Suunto SK8 was pointing to the piece of metal, while a Termos Pro (aka DGX Deluxe Pro) was pointing 30 degrees off. Maybe the needle under the card shifted, we thought. On a later examination, the reason why Termos was not pointing to the magnetic piece was because it has two parallel needles and the tip of one or the other needle will be drawn closest to the magnet. So it probably was fine and our issue can be blamed on either one of us not reading the compass correctly for whatever reason.
Part 3: responsiveness
While comparing the compasses, I noticed that the Suunto felt sluggish. My other compasses clearly moved around faster. Or were they? So, to compare, here's a video of all of them moving from 180 heading to a 0 heading:
From left to right that's:
- Aqualung (the same as an Apeks compass, I believe)
- Termos Pro, also known as DGX Deluxe Pro, I suspect it can be bough under other names too
- Suunto SK8
Part 4: my personal opinions
So far I've used the Termos as my workhorse. It's easily readable, good tilt tolerance, responsive, robust. It is quite tall (high profile), but it hasn't bothered me so far. Occasionally it will fall off the center pin when in the gear bag, but a small bump puts it back on centerl and level. I haven't dived with Aqualung yet (I just bought it as a replacement for the FS2 that I'm throwing away), but I might like it too - it has a softer, more clicky bezel that is easier to operate, otherwise it seems to share all the properties . Time will tell.
