Question Teric versus Perdix 2 for Recreational Diver

[inquis]

you should also enter the magnetic declination of your destination before you start diving too

Only do this if you intend to follow a bearing taken from a map oriented to True North. There's a very high likelihood that a bearing from a buddy is, in fact, a magnetic bearing without declination adjustment. Entering the declination on your compass introduces an error (which could be prohibitive to finding your destination).

 

[BoltSnap]

Only do this if you intend to follow a bearing taken from a map oriented to True North. There's a very high likelihood that a bearing from a buddy is, in fact, a magnetic bearing without declination adjustment. Entering the declination on your compass introduces an error (which could be prohibitive to finding your destination).

This error is insignificant considering the tiny distances we swim under/above water with our fins. If one was navigating with a boat and is traveling many miles/kms, it will make a difference.

 

[-JD-]

This error is insignificant considering the tiny distances we swim under/above water with our fins. If one was navigating with a boat and is traveling many miles/kms, it will make a difference.

IMO, vehemently, NO! I suppose you are speaking about good visibility conditions. Also, declination is about 3-4 degrees where you are and about 12 where I am, a factor of 3-4.


I did my UW Nav class in lovely, murky Dutch Springs quarry (viz frequently 20' 7m, occasionally vg, and not infrequently approaching arms length).

I could swim the box no problem, returning to start within feet, but I repeatedly followed my instructor's assigned heading to an outbound target and always missed it. Instructor was annoyed. I was pi..ed at myself.

Sat down with satellite images, examining the marker floats, and discovered that the facility-mapped heading was off by about 3deg. Well, that is 40' 14m at 100yds 100m, and when that is twice viz, it means only finding it if I swum wrong. With the corrected heading I could nail it every time. I razz him about Garbage-in, Garbage-out.

Point being, even a few degrees can make a difference depending on conditions. Always determine if a specified heading is magnetic or true and adjust accordingly.

None of that matters if you are setting and following the heading bug on a shot (vs. specified reference) course.

 

[BoltSnap]

IMO, vehemently, NO! I suppose you are speaking about good visibility conditions. Also, declination is about 3-4 degrees where you are and about 12 where I am, a factor of 3-4.


I did my UW Nav class in lovely, murky Dutch Springs quarry (viz frequently 20' 7m, occasionally vg, and not infrequently approaching arms length).

I could swim the box no problem, returning to start within feet, but I repeatedly followed my instructor's assigned heading to an outbound target and always missed it. Instructor was annoyed. I was pi..ed at myself.

Sat down with satellite images, examining the marker floats, and discovered that the facility-mapped heading was off by about 3deg. Well, that is 40' 14m at 100yds 100m, and when that is twice viz, it means only finding it if I swum wrong. With the corrected heading I could nail it every time. I razz him about Garbage-in, Garbage-out.

Point being, even a few degrees can make a difference depending on conditions. Always determine if a specified heading is magnetic or true and adjust accordingly.

None of that matters if you are setting and following the heading bug on a shot (vs. specified reference) course.

Yes, the amount of degrees matter, in my location is it <=3. Also, if you are taking the bearing at the beginning of the dive yourself, it doesn't matter then. If you are getting the bearings from somebody else and you want to hit the "X" exactly, you need to be much more careful especially if the adjustment is significant as in your case. If it is just knowing where the reef is and not a specific "X," it doesn't matter much.


BTW, is Dutch Springs officially closed to divers and used for some other purpose now?

 

[tridacna]

BTW, is Dutch Springs officially closed to divers and used for some other purpose now?

No. It reopens this year for training purposes only. Rules and regs have yet to be published but pleasure diving is essentially gone.

 

[-JD-]

Yes, the amount of degrees matter, in my location is it <=3. Also, if you are taking the bearing at the beginning of the dive yourself, it doesn't matter then. If you are getting the bearings from somebody else and you want to hit the "X" exactly, you need to be much more careful especially if the adjustment is significant as in your case. If it is just knowing where the reef is and not a specific "X," it doesn't matter much.


BTW, is Dutch Springs officially closed to divers and used for some other purpose now?

Agreed.

Stu sold Dutch to a giant commercial real estate development company and they are building 2 huge logistics warehouses at the front and the back corner (way past the concession stand/W bath house).

The lake portion was broken-out with a minimal amount of land and will be operated (soon) by the Atlantis Aquatics folks as Lake Hydra. At least for now, only Pros (DM or above) will be able to buy tickets and they need to supervise everyone they bring. A far, far cry from packing the van and camping/ diving a 3-day weekend, all on my annual pass.

 

[Belzelbub]

Thanks for all of the feedback so far. One follow-up question about the compass function of each model (compass is a huge issue for me): there was mention that the Teric compass needed to be calibrated daily or even before each dive -- does the Perdix compass need calibration that often too?

The Perdix will prompt for a compass calibration when you change the battery. Batteries are not all the same, so it's probably good to do it at that time as something has changed.

1.) I've never had a flood from swapping batteries in my old Oceanic Worldwide VT3, but find the process nerve-wracking, and I never know if I did it right till I dive with it. Every time I open and reseal the battery case, I risk compromising the seal and causing a flood. With a rechargeable battery computer, like my old Atomic Aquatics Cobalt 2, that is not a problem.

I'm betting the battery change process in the VT3 is similar to the VT4. The Perdix is A LOT easier. Rather than holding a cover with an o-ring in place while you engage the locking ring, you simply thread the cap in place. Cap has two o-rings in grooves. Really easy to do, and rather difficult to mess up.

 

[Divin'Papaw]

You get less dives from the Perdix 2 than the Perdix AI due to the vibration function and not being able to use a Saft battery (vibration alerts require use of Energizer Ultimate Lithium). I did 33 hour + dives on my Raja Ampat trip plus Bluetooth downloads of all dives - on the last few dives, the “fuel gauge” turned yellow, but I did not get a low battery warning - so I’d guess you could get at least 40-45 sixty minute dives which is in line with Shearwater’s spec (I also have brightness on HIGH for daytime dives and LOW for night dives).

You’re comparing apples to oranges. Turn off the haptics on the Perdix 2, and my guess would be you would get the same battery performance as the Perdix AI.

 

[Joneill]

You’re comparing apples to oranges. Turn off the haptics on the Perdix 2, and my guess would be you would get the same battery performance as the Perdix AI.

Ummm… that’s what I said.

 

[dedezelic]

I have a Teric and my wife has a Perdix - both just recreational diving. I got the Teric as I wear it as my watch when traveling for diving and love everything about it except for the fact that I’m about to send it in for the third time for battery issues (the second time the unit was replaced with a new one LoL). Seriously considering trading it for a Garmin but then I have to get a different transmitter as well.