Oceanic ProPlus-4 PDC

[MudBug]

From the PP-4 Manual:

ALTITUDE SENSING AND ADJUSTMENT

Altitude (i.e., ambient pressure) is measured upon activation and every 15 minutes until a dive is made.

• Measurements are only taken when the unit is dry.

• Two readings are taken, the second reading 5 seconds after the first. The readings must be within 1 foot (30 cm) of each other to record that

ambient pressure as the current Altitude.

• No adjustments are made during any time that the Wet Contacts are bridged.

• When diving in high altitude waters from 3,001 to 14,000 feet (916 to 4,270 meters), the ProPlus 4.0 automatically adjusts to these conditions

providing corrected Depth, and reduced No Deco and O2 Times at intervals of 1,000 feet (305 meters).

• When the Conservative Factor is set On, NDLs are calculated based upon the next higher 3,000 foot (915 meter) Altitude.

• At Sea Level, calculations are based upon an Altitude of 6,000 feet.

• All adjustments for Altitudes greater than 11,000 feet (3,355 meters) are then made to allowable dive times for 14,000 feet (4,270 meters).

• The ProPlus 4.0 will not function as a Dive Computer above 14,000 feet (4,270 meters)

Note the line I have bolded and underlined.
If I am reading this correctly, the PP-4 adds 6K feet to a sea level reading before it starts its calculation?

Am I understanding that correctly? Or does it mean at sea level, with Conservative Factor On, it starts off at 6K?

Man, adding 6K to a sea level reading would explain why my NDL times is so short.

 

[MudBug]

This article has probably been posted before but is relevant to the topic.

 

[Belzelbub]

Am I understanding that correctly? Or does it mean at sea level, with Conservative Factor On, it starts off at 6K?

Man, adding 6K to a sea level reading would explain why my NDL times is so short.

I’m not entirely sure. Not the best written manual, it’s unclear if each bullet is independent or if the bullet above it applies.

I’d hope it would mean that if conservatism is set on, at sea level it assumes 6000’, then from there it would essentially assume 3000’ foot higher.

I’d definitely reach out to Huish. They’ve been pretty responsive when I’ve contacted them in the past.

 

[MudBug]

I’m not entirely sure. Not the best written manual, it’s unclear if each bullet is independent or if the bullet above it applies.

I’d hope it would mean that if conservatism is set on, at sea level it assumes 6000’, then from there it would essentially assume 3000’ foot higher.

I’d definitely reach out to Huish. They’ve been pretty responsive when I’ve contacted them in the past.

My LDS is doing this for me, arranging an introduction so to speak. One of the advantages to buying from a local merchant.
Hopefully we will get this sorted out.

 

[MudBug]

Why would you make Sea Level = 6K feet. From what I remember of the old PADI tables, Sea Level was Sea Level.

 

[Belzelbub]

Why would you make Sea Level = 6K feet. From what I remember of the old PADI tables, Sea Level was Sea Level.

It's a way to add some level of conservatism to the algorithm. I think Sea Level is only 6K feet when Conservatism is on, but it is worded a bit ambiguously in that manual.