KiSS Ocra Spirit needs some modification Part I

Back in February this year, I went to Krabi Thailand to receive some cave dive training. While I was there trying to hover steady and do some skill, I figured I had hard time trying to stay balance as well as stay horizontal….. It is not as critical while diving open water, but in a cave, confined and silty area, it is crucial. So I thought some change or modification of both my set up and my breather is necessary.
When we talk about posture of diving, we often say: TBBBP. T is trim, which is basically the position of you body while in the water; B is balance, which is whether you are balance or not, left heavy, right heavy, top heavy or bottom heavy; second B is buoyancy, simply is whether or not you are maintaining neutral; third B is breathing, which is important to a certain extend but doesn’t really affect your posture while diving CCR (very important while OC diving though); and lastly P of course is propulsion, how you move forward or backward. Being said that, when we look at the KISS Ocra Spirit, which is the rebreather I dive, it has no on board Dil, (in fact I’ve never feel too comfortable about because of the lack of redundancy), also it has the O2 tank mounted horizontally at the bottom.

Off board Dil causing you left-heavy ( I typically side mount my off board on my left side) when beginning of the dive eventually change to left-light by the end of the dive also depending on the type of cylinder I carry, or available to me. It is not a very big deal if the off board is only for the purpose of bail out since you can fill the tank to neutral. However in this case it is also your diluent gas supply. So half way through the dive, your left side will become lighter or neutral or even positive after consuming some of the gas in the cylinder.

Having the O2 cylinder mounted horizontally, making it right- heavy due to the tank valve on the right hand side. But unfortunately these left-heavy and the right-heavy they don’t balance it out and that explains part of the reason why the rig is off balance. Having the O2 cylinder mounted at the bottom of the machine, also will make the diver bottom heavy, especially diving wet suit and this explains part of the reason the same diver cannot stay horizontal and needed to trim out….
In the next issue I will let you know how I think I can solve my problem, and what I have done to my set up and modification of my OS. I had in fact done some testing in the swimming pool with the unit and been making some minor adjustment here and there. Hopefully next week I will be able to test it more in open water while I am in Cayman. I will see how it goes. Please stay tune and come back in the next few days, I will carry on talking about the progress of this modification.


One thought on “KiSS Ocra Spirit needs some modification Part I

  1. How much dil are you going through on a dive that you notice a change in your balance? During an average 2 hour dive, I don’t think I normally use more than 300 PSI from an AL40.

    If you’re concerned about balancing out your rig AND redundancy, why not carry a second AL40 on the right side?

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