Another PADI - SSI ?? Dive Tables ??

[bruce119]

I got my OW a few years ago PADI. Now I'm advancing getting some specialties. The shop has switched to SSI. I all ready researched the PADI verses SSI thing and it didn't seem to be too much of a problem.

Now the first problem ........ I'm taking SSI Deep Diving. Now I'm on the last chapter when you need your tables. I have my original PADI tables. The scenario they give you in the SSI Book does not work the same. It's close but doesn't work the same as the SSI book.

Is the SSI tables different than PADI ??

Thanks
Bruce

 

[Web Monkey]

I got my OW a few years ago PADI. Now I'm advancing getting some specialties. The shop has switched to SSI. I all ready researched the PADI verses SSI thing and it didn't seem to be too much of a problem.

Now the first problem ........ I'm taking SSI Deep Diving. Now I'm on the last chapter when you need your tables. I have my original PADI tables. The scenario they give you in the SSI Book does not work the same. It's close but doesn't work the same as the SSI book.

Is the SSI tables different than PADI ??

Thanks
Bruce

The tables are different. You'll need SSI tables to do any of the exam questions.

PADI allows more bottom time and a deeper maximum depth. They can't, however change physics, so if you're diving to the edge of the table, the PADI tables allow more nitrogen accumulation.

Terry

 

[mixdiver]

The SSI tables are base on the Navy dive tables. They should be pretty cheap. I think they come with the nitrox course book if you are going to take that as well later on.

 

[Rick Murchison]

You can download the entire Navy Diving Manual here.
The tables are in there.
Rick

 

[diverdown247]

The newer SSI table is based on Doppler as opposed to just a mathematical formula derived from the Navy tables. Padi tables will be a bit more conservative, but they will have near the same results, though you may be in a different residual nitrogen category (usually one off up or down depending on the chart).

If you talk to your SSI instructor, they may loan you a SSI chart for the class. Otherwise, explain the situation and see if they will adjust/check your answers on the test questions for the Padi tables. As a last resort, get the SSI doppler table.

I currently carry with me the SSI doppler, PADI RDP, and PADI Wheel all depending on who I'm diving with and what chart they prefer to use. Then again, after having to use my rescue training, I try to keep at least 2 systems in my folder.

 

[Walter]

Padi tables will be a bit more conservative, but they will have near the same results, though you may be in a different residual nitrogen category (usually one off up or down depending on the chart).

PADI tables (RDP) are LESS conservative, not more. They are more conservative than the US Navy tables ONLY for a single dive.

You also cannot switch back and forth between tables. A "G" letter group does not represent the same amount of residual nitrogen on the RDP as it does on the Navy tables.

 

[Charlie99]

The newer SSI table is based on Doppler as opposed to just a mathematical formula derived from the Navy tables. .

(Walter already took issue with just about every other statement, so I'll just address this one.)

Unless you have some weird SSI table I've never seen, it is based upon some same mathmatical formula as the Navy tables/NOAA tables. The only thing that has changed is that they have reduced the limits slightly. That's why the residual nitrogen letter groups are identical between SSI, USN, NOAA and the many other USN-derived tables.

The PADI pressure groups are based upon the 60 minute halftime compartment. The SSI and USN repetitive letter groups are based upon the 120 minute halftime compartment. You can't switch back and forth from PADI to the others.


-------------------

PADI tables (RDP) are LESS conservative, not more. They are more conservative than the US Navy tables ONLY for a single dive.

The deco model upon which the RDP is based is more conservative than the model upon which the USN tables are based. This is true for each and every compartment of the USN and DSAT/PADI models.

The apparent conservatism of the USN tables on repetitive dives is simply caused by the 120 minute halftime compartment used by the USN tables being a poor choice for tracking recreational dives. Dive tables cannot track or plan a dive as precisely as a dive computer or decompression program. The USN table does a particularly poor job on tracking and planning repetitive single tank dives, even when diving square profiles.

PADI/DSAT more accurately tracks and plans repetitive dives by using a controlling compartment halftime that is more appropriate for scuba. Those few dives where the controlling compartment is slower than 60 minutes (extraordinarily long shallow dives) are handled by the W,X, Y, Z rules which mandate either a 1 hour or 3 hour minimum SI under a few unique circumstances when doing 3 or more dives per day.

 

[boulderjohn]

The apparent conservatism of the USN tables on repetitive dives is simply caused by the 120 minute halftime compartment used by the USN tables being a poor choice for tracking recreational dives. Dive tables cannot track or plan a dive as precisely as a dive computer or decompression program. The USN table does a particularly poor job on tracking and planning repetitive single tank dives, even when diving square profiles.

PADI/DSAT more accurately tracks and plans repetitive dives by using a controlling compartment halftime that is more appropriate for scuba. Those few dives where the controlling compartment is slower than 60 minutes (extraordinarily long shallow dives) are handled by the W,X, Y, Z rules which mandate either a 1 hour or 3 hour minimum SI under a few unique circumstances when doing 3 or more dives per day.

Nicely stated!

 

[Rick Murchison]

The deco model upon which the RDP is based is more conservative than the model upon which the USN tables are based. This is true for each and every compartment of the USN and DSAT/PADI models.

The apparent conservatism of the USN tables on repetitive dives is simply caused by the 120 minute halftime compartment used by the USN tables being a poor choice for tracking recreational dives.

Hmmm... let me see if I've got this straight... on repetitive dives the Navy tables (doppler limited) let me dive less than the PADI tables, so they are only apparently more conservative and actually less conservative and so they're a poor choice for tracking recreational dives...
Have I got that about right???
Rick

 

[diverdown247]

Thanks Charlie for the further info. I should have been more specific with the PADI base info.

The other issue is that PADI RDP doesn't start until 35 feet where the SSI table starts at 10 feet and has 5 foot increments up to 40 feet.

Walter, I don't swap between the charts on any dive. It's a bad safety idea. When I start a new dive day, depending on who I'm diving with, will dictate what dive planner I use. If someone is PADI certified I use the method they are familiar with and stay with it the entire dive series until our dive sessions (not just that day) are discontinued. I see how my previous post may have been misunderstood.