November 14th, 2007

NiTek X GF Update


We have updated the GF factors for the NiTek X, specifically the CONO GF. See Phil’s comments below:


Based on your input, we have re-worked the gradient factors and have a new GF for CONO as follows:

CON0 : GF 75/95
CON1 : GF 40/100
CON2 : GF 30/75

Briefly. CON2 is Eric Baker’s conservative base assumption, “if you want conservative, use this”. CON1 is good low GF but no surface penalty over an above the deep stop time “this gives considerable deep stops but does not extend shallow deco too much”, CON0 base level safety “Some movement of shallow stops deeper to hint at deep stops, for recreational use”.

I labored most over CON0. Use the Workbench to try these profiles. You will notice that 75/95 has the characteristic that for serious or less serious recreational dives the deco is hardly longer, but does move one or two stops deeper in the water and spread the deco over a deeper range. It is more conservative by “deep stop” rules for this reason. Eg. for a 130 ft dive that usually yields a Buhlmann deco starting with one minute at 9M you will see a few minutes at 12M followed by a slightly longer deco, total. This happens because you need to stop earlier because of the LO-GF, but you are not on-gassing still (much) because you are shallow enough. So the deco is actually more graceful by the same “deep stop rules”. It is more complicated than that physiologically, but as far as the model maps to this I think we are in bounds.


November 12th, 2007

RBW O2ptima Rebreather Inquiries


The O2ptima manual needs a few updates. We have been working on a few items to add before making the next revision.

These include:

  1. The new Delrin HH are easy to use and have some firmware updates added, including a battery indicator.
  2. The premix rod was to be taken out of the unit, but I found that on rapid descents the premix rod is advantageous. I assumed instructors would address this until we got a new revision of the manual out. We use a new connector to help with alignment and it is easy to remove when servicing the head. The grommet should be at the base above the sensor disk so the EAC pushes against it to seal against CO2 bypass. I do not recommend putting it on top as it will surely get lost during assembly.
  3. The new quick release elbow for the premix rod has a flow restrictor to maintain a constant flow from solenoid and adjust for variations in the solenoid orifice.
  4. New accessories include an inline solenoid shutoff.

We are gathering the Micropore test data and will soon post it. I realize there are some questions since the release of the CE comparison test data just before DEMA. We have reviewed it the test data. Dive Rite is not a European company so we didn’t build the O2ptima to CE specifications. We built a CCR around new technology and based our performance on US Navy standards, something a little closer to home. We were able to build a smaller, more efficient unit than our competitors.Now that we have built a CCR on a unique platform we will start modifications to go for CE approval. The problem is that CE standards are written for older technology, but if CE standards are not updated, we will evaluate the necessary changes to meet the CE directives.

If you want to know about the performance of the O2ptima, just ask the divers using it. I am always available for a dive when you visit North Florida. You dive your unit and I will dive the O2ptima.


November 12th, 2007

Jetstream Handles Sidemount Squeeze


I finally got a chance to go side mount diving after DEMA. Jerry Murphy, our Product Manager, and I did Rock Bluff and had to dig the entrance out just to get in. I felt this would be a good test for the JetStream Regulator. I wanted a regulator that I could breathe from the left side without running it around my neck when side mounting. The JetStream worked very well. It secures to the left shoulder with a bungee strap around the webbing to keep it high and out of silt. I had our new regulator necklace (debuted at DEMA) on the right side regulator. The adjustable regulator necklace let me pull it up tight for side mount…a little tighter than most divers would wear a regulator for back mounted cylinders.


  1. Both regulators – I had to dig some small rocks out of the first stage caps – yeah it was very tight.
  2. The necklace works just as designed, but I am having the manufacturer change the crimps before production is released so it will be another 30 days before we have stock.
  3. Nomad bottle placement is good with the new chokers on the necks. This was my first chance to use them in a small restriction situation. I had tested them, but had not had the chance to test the tank placement with chokers in a tight body squeeze.

I routed the Jetstream second stage hose downward in order to make the standard 28-inch hose length lie flat. It pulls up easily for use.