OceanLog beta version 2.1.4 Available

[cummings66]

A warning to those with Vista 64 (dual Processor)

Dont install the new version over the old one, you dont end up with the latest version.

I had the same thing happen to me and I don't have Vista 64. I moved my data file away and reinstalled the program. The thing is, I was fine with the last release, but this one did not copy the program file into it's proper slot.

I'm betting they changed something permission wise and the old one had permissions that would not allow the update to install over the top of it.

I'm fine now, but just wanted to say that a second person had this happen. No big deal for me since it was obvious. I figured it out when it said it couldn't find the oceanlog.hlp file and I was like, they were supposed to fix that to work and it doesn't. 2 seconds later I discover why.

 

[TheGoast]

Just wondered what every one else thinks about the Tank section.

As there is diferent info given to calculate SAC depending on wether we are woking in METRIC or IMPERIAL.

At present Cylinder Size is used for the fisical size of the cylinder when working in Metric and used for the capasity of air at 1 ata in the cylinder when working in Imperial.

Since the program alows you to switch between Metric and Imperial I dont see how the Cylinder size box will work.
It must be giving the programer nightmares.

The way I see it, to make it less confusing is to have another text box added.

Insted of:
Working Pressure: (used by Imperial users)
Cylinder Size: (used by Imperial users and Metric users)

We have:
Working Pressure: (used by Imperial users)
Cylinder Capasity: (used by Imperial users)
Cylinder Size: (used by Metric users)

This way changing between metric and imperial would work.


What do you think?

 

[rakkis]

That's over complicating the problem.

I'd be simpler to implement something like this:

A boolean called metric. Can be set by the user in preferences for a new dive's default value. Can be overridden in each dive.

The air consumption function would go:

float calculateAirConsumption (metric, tankSize, airUse() ) {
if metric { do metric calculation and return};
else {do imperial calculation and return};
}

There is no need to confuse the user with fields that they'll need to leave empty.

 

[TheGoast]

That's over complicating the problem.

I'd be simpler to implement something like this:

A boolean called metric. Can be set by the user in preferences for a new dive's default value. Can be overridden in each dive.

The air consumption function would go:

float calculateAirConsumption (metric, tankSize, airUse() ) {
if metric { do metric calculation and return};
else {do imperial calculation and return};
}

There is no need to confuse the user with fields that they'll need to leave empty.

You must be an Imperial user, Metric users leave Working Pressure empty they dont need it.

 

[dsevern]

Goast...thanks for digging even more.

Yes, it seems the "working pressure" is the missing variable that allows SAC to be calculated using Imperial.

My question is this: What is "working pressure"? It would seem to me to be the same as "starting pressure", wouldn't it? I'm using a ProPlus 2 computer.

I guess I really don't understand how working pressure comes into play with the SAC calculation.

For Imperial, my tank size was 80 cu./ft. A "precise" fill would put it at 3200psi, however depending on who did the fill, I'd expect anything between 3000 and 3300psi...so it would seem that "working pressure" should be the same as "starting pressure"....or at least that's what seems logical to me.

BTW, when I enter a working pressure AND Tank Size it does now calculate SAC and save the values for Tank Size.

So...I guess I just need to know what value to really use for "Working Pressure".


Responses are greatly appreciated!

 

[TheGoast]

Goast...thanks for digging even more.

Yes, it seems the "working pressure" is the missing variable that allows SAC to be calculated using Imperial.

My question is this: What is "working pressure"? It would seem to me to be the same as "starting pressure", wouldn't it? I'm using a ProPlus 2 computer.

I guess I really don't understand how working pressure comes into play with the SAC calculation.

For Imperial, my tank size was 80 cu./ft. A "precise" fill would put it at 3200psi, however depending on who did the fill, I'd expect anything between 3000 and 3300psi...so it would seem that "working pressure" should be the same as "starting pressure"....or at least that's what seems logical to me.

BTW, when I enter a working pressure AND Tank Size it does now calculate SAC and save the values for Tank Size.

So...I guess I just need to know what value to really use for "Working Pressure".


Responses are greatly appreciated!

I will try to explain a bit more also read TheTrickster's post erlier.
to work out SAC you need to know the fisical size of the cylinder.
Your cylinder is an 80 (80 cu.ft.) this is not the fisical size, it is its capasity when it is filled to the working pressure (3200 psi).
Fom this you can now calculate the fisical size.

change psi to bar.
devide capasity by bar gives fisical size.

now that you know the fisical size of the cylinder you can work out how much air you have if it is filled at diferent pressures.

change psi to bar.
multiply fisical size by bar gives how much air is in cylinder.

you will find the WP (working pressure) stamped on the Cylinder.

hope this helped a bit.

 

[cummings66]

My question is this: What is "working pressure"? It would seem to me to be the same as "starting pressure", wouldn't it? I'm using a ProPlus 2 computer.

I'll give a real world example. I dive HP100's and HP120's. The working pressure is 3500 psi, but in real life I almost never have fills to that and often will have 3200 psi, and have on occasions gotten 2500 psi fills. 2500 psi isn't nearly the amount of gas that cylinder will hold.

Working pressure is a very important value to figure out how much gas you would breathe because the number is used to tell you how much gas is in the cylinder.

Your common run of the mill AL80 at 3000 psi and 77.4 cf of air is another example of a cylinder, all the data you need to figure this out as Ghost said is stamped on the cylinder neck.

 

[robertarak]

SO, to figure out SAC rate, do you use the starting pressure as working pressure on the tank tab??? That makes sense, and if so it would make sence to just import this data from the computer. If we were to use the working pressure stamped on the tank, with a short fill, or even second dive on the same tank with no fill, the SAC rate would be calculated far different from reality.

 

[TheGoast]

SO, to figure out SAC rate, do you use the starting pressure as working pressure on the tank tab??? That makes sense, and if so it would make sence to just import this data from the computer. If we were to use the working pressure stamped on the tank, with a short fill, or even second dive on the same tank with no fill, the SAC rate would be calculated far different from reality.

No you need "working pressure", "start pressure" and "end pressure"

all three pressures are needed for imperial calculation.

 

[bperrybap]

No you need "working pressure", "start pressure" and "end pressure"

all three pressures are needed for imperial calculation.

In reality you need all 3 regardless of whether the calculations
are done in imperial or metric. The full true calculation
is identical for either system of units.
When you work through the math using all the appropriate units
(PSI, CuFt, L, BAR, etc..)
if you don't use a working pressure in metric, you will get the
correct numerical answer but you will not end up with the
correct volume units.

Many folks leave off the units when doing their calculations
and slam on the final units because they know what
they should end up with. Thats where they get into trouble.

The "working pressure" can best be thought of as
"What should the pressure inside the cylinder be set to
in order to achieve the quoted volume?"

In metric this is simple since ALL their volume ratings are done
as an empty volume. They are effectively all at the same pressure (1 ATA, or 1 BAR).
Since it is numerically "1" and doesn't affect the numerical
value of the calculation it is often left out of the equations.
But in reality it is still needed to make the units come out
correctly.

In Imperial, working pressure is not as simple.
It is all over the place. For aluminum 80s the working
pressure is around 3000 PSI. That means you need
3000 PSI to have 80 cubic feet of air in the tank.
You could just as easily have said that the tank volume
was 40 cubic feet with a working pressure of 1500 PSI.
The SAC calculation would be unaffected.

Working pressure has nothing to do with the starting or
ending pressure you see on your gauges during your dive

Here is a repost of my comment from a previous SAC thread
on this topic:
SAC Thread
--------------------------------------
With metric sizing the size/volume of the tank reported
is with a working pressure of atmospheric pressure or empty.
With imperial sizing, the size/volume of the tank reported is at the
rated workingpressure or full.

With metric you also have to know the working pressure as well,
(The full equations for metric and imperial are actually identical)
but because it is atmosspheric pressure in metric,
it all divides out and the equations are typically simplified.

With imperial because the volume of the tank reported is not
the empty volume, you have to know the working pressure
used for the reported volume.

Metric calculations get a freebie and can be simplified because the
working pressure is 1 pressure unit (1 BAR) and divides out.
In Imperial the volume isn't at a working pressure of 1 pressure
unit (1 PSI), so you have to account for it in the equations.
Even if Imperial used volumes of empty tanks the math would still
look more complicated because in Imperial atmospheric pressure
is not 1 pressure unit like it is in metric.


If you write down the full equations with all the units it will
become clearer.
Don't be mislead that there isn't a working pressure for Metric.
There is. It is usually left off because it is 1 and doesn't
affect the numeric portion of the answer.


For example lets look at the full equation:
vol = ((Start Pressure-End Pressure)/Working Pressure) *Tank Volume

In Metric, many folks will tend to short cut this into:

vol = (Start Pressure-End Pressure) *Tank Volume

However with real values AND units you will immediately
see the problem.

If you take the short cut
vol = (200 BAR - 50 BAR) * 15 Litre

You end up with:

Vol = 150 BAR * 15 Litre
Vol = 2250 BARLitre

What the heck is a BARLitre ?
You want to end up with Litre (L) not BARLitre or BARL

But if you use the FULL equation which includes the working
pressure you end up with the correct units.

Vol = ((200 BAR - 50 BAR) / 1 BAR) * 15 Litre
Vol = 150BAR/1BAR * 15 Litre
Vol = 150 * 15 Litre
Vol = 2250 Litre
Vol = 2250 L

The units all divide out properly.
You need that working pressure to divide out the pressure
units to leave you with just a proper volume unit.
So many people try to take short cuts and make mistakes
by leaving off the units and then slapping them on the end number
because they know what the units of final answer should be.

You can cheat and can get away leaving off the working pressure in
metric; however, in Imperial you cannot.

For me, I always do equations and conversions with full units.
If the equations are correct, the proper units will be left.

--- bill