Bottom Timer and dive computer

[PerroneFord]

LOL. When you, or PerroneFord, or SparticleBrane post something derogatory about computers, it's a pretty safe bet that you are parroting the DIR line.

Why was this even necessary? I even offered an example of how I bent my Vyper when I used it as a computer and got locked out. How is my DIRECT experience bending my OWN computer on a decompression dive, parroting anyone?

 

[Gil57usa]

I use a Cochran EMC-16 computer and an old Princeton tech mechanical bottom timer. They are within 30 seconds accuracy of each other.

 

[atedeschi]

From reading most post it sounds like the reason for not using computer mode and using gauge mode is to allow you to get out of the water faster. But it is not going to hurt you to hang alittle longer at your 10 ft stop.

To answer the question about BT or computers, I have a DR Duo and OMS BT. I plan my dives with V-planner. I just dove FRI-SUN did about 8 dives in the 145ft-115ft range and my computer and vplanner were pretty close together. The computer would have me stay maybe an extra couple of minutes at 10ft but it can only help not hurt.

Note the Sit times are put before the dive but they are the sit times between dives.

Here is my profile from the trip:

SI: 03:00 Profile: (140, 25, 21) Deco: 71,
SI: 05:00 Profile: (145, 25, 24) Deco: 75,
SI: 11:45 Profile: (115, 25, 28) Deco:
SI: 02:30 Profile: (115, 35, 29) Deco:
SI: 02:30 Profile: (115, 30, 30) Deco:
SI: 02:00 Profile: (115, 40, 30) Deco:
SI: 11:30 Profile: (115, 30, 31) Deco:
SI: 24:00 Profile: (115, 40, 31) Deco:

 

[Scared Silly]

I use a bottomtimer with cut tables a primary and a Vytec as a computer back up. In the few deco dives that I have done the tables and computer are in agreement for the most part. For instance, I had a gas switch planned for 90 feet and the computer wanted a deep stop at 85 feet. I did the switch at 87 feet and everybody was happy.

I think the key for me is knowing what the computer is going to do a head of time. Although about the first time the computer does something like what PF experienced I might be thinking twice.

 

[Nemrod]

"Does anyone still use a mechanical watch for a bottom timer or a mechanical depth guage?

The reason I ask is because these two items are rather important in diving, whether technical or recreational and are typically (always?) "electronic." Yet one of the big complaints about the use of a computer, as opposed to a bottom timer, is that it is "electronic" and "everyone knows that salt water and electronics don't mix" which is why the brass SPG is the choice for providing pressure information.

IF it is so much better to have a mechanical SPG, why isn't it better to have a mechanical bottom timer (aka watch) and mechanical depth guage?"

Of course people still use mechanical watches for diving--I do. I have three, Heuer Professional (curca 1978 as gift), Seiko Orange Monster (my beater) and DOXA Sub600T (a classic dive watch for our 25th). All are fully mechanical auto winding watches. The DOXA is the coolest. The Seiko Orange Monster is not terribly expensive and it is expense that proabably causes most people to balk at a mechanical watch--ie--a for real watch. In the USA watches have always been thought of as a cheap throwaway item and thus people balk at paying a couple of thousand for a real mechanical watch. Fortuantely some such as the Seiko can be had for a few hundred but are hard to find in the USA. Mine came fom Hong Kong with an international warranty. It is a great watch, heavy, stone cold reliable and darn UGLY--it is great.

I dive the original Navy tables and use a mechaincal Princeton Tectonics timer and a real dive watch for time and reducndancy. N

 

[VinceDS]

On a technical dive I carry an Uwatec Digital Bottom Timer, an Oceanic Versa Pro set to gauge mode, and a mechanical watch. I use V-Planner to cut tables and carry two sets of the same dive profile in two different locations on my person (1 copy in wet notes and 1 copy laminated).

I keep my computer in gauge mode because I hate the constant violation beeping during deco...and the eventual flat line tone w/ lock out after I surface

 

[SDAnderson]

~
IF it is so much better to have a mechanical SPG, why isn't it better to have a mechanical bottom timer (aka watch) and mechanical depth guage?"

Hmmm. Interesting question. I think you have identified an internal inconsistency in one of the arguments used by many divers against computer usage.

 

[PerroneFord]

Just my opinion:

The SPG is the ONLY piece of information you cannot get from a buddy or team member. In a team of three, the timer, depth guage, etc are all redundant amongst the team. But the SPG is not redundant.

 

[Peter Guy]

(I don't know if I should start this new on the DIR forum or continue it here -- which I shall -- in hopes of getting a "proper" answer.)

PF replied to my question regarding the SPG that it is the only non-redundant piece of equipment the team has. If true (and I believe it is) then, by my understanding of the rule of redundantcy, the SPG is a non-critical device and the redundant information about tank pressure comes from a knowledge of three things, diver's RMV/SAC, time and depth (which is consistent with the training of being able to estimate one's pressure at any time during the dive).

BUT, if the SPG IS a non-critical device, then why would it matter so much that it be of only one kind -- chrome plated brass with glass cover?

 

[*Floater*]

BUT, if the SPG IS a non-critical device, then why would it matter so much that it be of only one kind -- chrome plated brass with glass cover?

I think the oil-filled brass/glass SPG's are preferred by some people simply because they are more rugged and will last longer than other types. I have some small plastic cover SPG's also for deco bottles (because they are lighter), but they also look much wimpier, and I've heard about the needles sticking and the face getting scratched on plastic cover SPG's, though this shouldn't be an issue at 70' or 20' where I use the deco bottles (plus I add a thin adhesive sheet/tape to protect them from scratches).