diving with a kiss vs inspiration/evolution

[Ken]

Originally Posted by Mr.Dave

I've just bought a second hand inspiration after several months of pondering over the same problem.


So the choice was a second hand insp or KISS.

Although the KISS is simple to operate & less cluttered the benefits of the insp pushed me down the AP route.

Some of the reasons I chose the insp over the KISS are:

Spares easier to get hold of & customer service (bigger company + company reputation)

Resale (as I say I'm not sure how I'll find RB diving) - easier to shift an insp over a KISS just because people are more likely to trust/buy something they see on a daily basis (advertising wins!)..

Ins RB courses are a little better established.

No major modifications after every other batch (02 valve & new switches on back of KISS hand set)

A lot more people to help you (two of my friends have insp units)

New KISS is same price as new insp (after all extra bits, import, VAT, etc are added)

& one major one: on ascent if you loose the plot it tries to keep you alive by pumping o2 into the loop!

Hope you find the decision easier than I did...

I dive both units and instruct on the Inspiration. I find some of your reasons valid from the perspective of living in the UK vs. North America where KISS is located. However, there are a tons of KISS divers in the UK as well as instructors. They can probably answer a lot of your questions

If you're considering a rebreather I would suggest having a test run with both units in the pool. WOB and non-electronics vs. electronics would become apparent during an extended run in the pool. I don't find the differences huge, but others might. The KISS valve can be a a minor chore sometimes, as you are constantly monitoring your PO2, but then again you are doing that with electronically monitored models anyway. Many divers using electronic units fly their units under manual control.

If you go to the Jetsam site you can find instructors in the UK who can give you a go.

The decision to get a KISS was for ease of travel, not dealing with electronic tomfoolery and the ease of getting parts - they are readily accessible via Jetsam (great customer service) or through some third party. The KISS classic is essentially a sophisticated homebuilt unit. Since there are no built in dil. ad buttons, as well as ways to dump water another unit might be considered if you plan on doing some harsher diving later down the line.

[nigelH]

Originally Posted by max101

as i said i am not yet a rebreather diver, i may also be over complicating things but i like many other people i dont really trust electronics in water,

The electronics normally isn't a problem. We YBOD owners do angst about packing the scrubber (the one thing your instruments can't tell you about) and we grumble about switches and batteries but the electronics itself just goes on and on. When was the last time your dive computer packed up?

this is probably a crazy idea but what if you were to add a kiss valve to the inspiration so that the valve did most of the work then when neccesary the electronics did their bit, i.e. increased workload so more more o2 needed ?

I'd vote crazy idea. You still need to check the handsets so where is the gain? The whole advantage of the ECCR is that if you are distracted it keeps going. If you are sorting out your buddy and miss a check it keeps the O2 bang on the money. You never assume it but all you are doing is checking most of the time. The KISS is a great piece of kit but muddling the two wouldn't be adding but taking away. The sensors measure the oxygen and the computer tries to inject to correct it. If you second guess it by injecting O2 you can expect it to overshoot. Since we are riding the curve of CNS to get 3hrs duration this isn't something you want to do breath by breath.

[max101]

like i said im not a rb diver, but i think you are missing my point, primarily, surely it act as a kiss unit then IF it needed to IT would inject more o2 automatically to maintain constant pp02

[Mark Chase]

Originally Posted by max101

like i said im not a rb diver, but i think you are missing my point, primarily, surely it act as a kiss unit then IF it needed to IT would inject more o2 automatically to maintain constant pp02

If the KISS valve was set to give you 1.3 and you set the YBOD to 1.2 it would sort of work but using a constant mass flow on a YBOD would trigger the dammed alarms all the time on decent and would piss you off in the end. There is just no point to it. The YBOD works and works well 99% of the time and when it doesn’t you have to run it like a KISS.

The YBOD will spike if you descend too fast but you have to ascend pretty rapidly to beet the solenoid on the way up. The big issue with the KISS is how much time during a dive you have to spend on keeping your PP02 within working parameters. The big issue with the YBOD is that it just works all the way up until the day it doesn’t. Complacency will kill you. Personally I like to have the HUD to keep the info in my face at all times. Even if I dived a KISS I would want one.

On the secondary issue of transportation: The Evo solves the problem of size and weight but the KISS is definitely more transportable than the YBOD. The Meg is a very very happy medium

ATB

Mark Chase

[nigelH]

Originally Posted by max101

like i said im not a rb diver, but i think you are missing my point, primarily, surely it act as a kiss unit then IF it needed to IT would inject more o2 automatically to maintain constant pp02

I think you need to go and read up on how you fly a KISS because a KISS does not run a set point and if it did maintain one it is way out of adjustment and going to eat DIL.

Putting this up against an Inspiration which measures the ppO2 and calculates how long a burst of O2 to inject and you are going to make the whole system unstable as the computer thinks it has to add what is coming in through the KISS valve and then discovers it has overshot. The YBOD inject system is not like a thermostat that turns on the heat when things are cold and waits until it warms up, it measures the error and injects the correct quantity to fix the deviation from target.

[The Purist]

Back to your original question.... what's the difference between diving them? Well.... one person who could have answered that from 1st hand experience now can't (hint - RBW may be another place to ask this if you haven't already). One of the folks I dive with has moved from Inspo to KISS as well - I've been diving a KISS since 2001 and have a tiny bit of experience on the Inspo, so here's a blow by blow comparison based on my own experience - others may well have different opinions:

Setup: Both will need a similar amount of effort for cleaning, maintenance, assembly and checking. +/- checks, batteries etc are all much of a muchness. The Inspo can be disassembled without tools, the (classic) KISS requires you to have a small fettling box.

Pre-dive: The Inspo has a calibration routine that interprets the output of your cells - no such animal on the KISS, you have to tweak pots on the displays to calibrate them to air/100%. During the pre-breathe you can check the function of the inspo solenoid as well as the KISS valve. The Inspo will automatically maintain the low setpoint for you, whereas the KISS will require you to establish your own surface set-point.

Descent: The KISS has an ADV as standard, so descent is hands free, apart from checking the displays. AFAIK most people ride the Dil on the way down rather than trying for any particular setpoint. An Inspo without ADV requires manual Dil injection on descent to keep the c/lungs inflated but many users elect to fit an ADV. Inspo will maintain a setpoint on descent.

At bottom: Inspo is a switch to select higher set point, KISS has to manually inject O2 to achieve desired set point.


During dive: Inspo maintains set point (but handset checking still required) - KISS has O2 flow matched to metabolic rate (ish) so with a well set up KISS, in a steady state on a flat bottom you can go 10-15 mins without needing to touch the O2 (did a drift in the dark off Lulowrth back in Feb and thought my displays had frozen!). Expending effort or wobbly bottom profile can require more frequent O2 injection, but this is a reflex touch on the button with a handset check a few seconds later. Displays on the KISS are in an easy to check place (eft forearm), Inspo handsets tend to be clipped off so more work to look at them, but familiarity with your kit means that becomes easy.

Ascent - Inspo maintains set point again, KISS becomes a great tool for displaying the laws of physics as PO2 drops on ascent. Reality of this is that you adopt a different deco strategy as constant PO2 deco on the KISS is (1) a lot of work and (2) a waste of O2. Depending on your thoughts on deco you may prefer to avoid constant PO2 deco anyway, so perhaps not much to choose between them.

Surface - Again Inspo maintains PO2 whereas KISS can still have a go at you right up to the moment you spit the DSV when you're sat on the bench.

Maintenance - Jetsam's customer service has been second to none so far - when after spares (normally enhancements) Gordon has been known to ship before asking for payment. The whole 'evolution' of the KISS (sorry!) agaisnt the static state of the Inspo is IMHO partly due to the CE marking issue. Major changes to the Inspo will require resubmission, whereas the KISS can evolve as Gordon's mind devises better solutions. Everything to date has been backward compatible, so I could choose to upgrade mine to the latest spec if I really wanted to. AP are no slouches when it comes to service themselves HOWEVER one big difference is that you can stick enough spares in a small box to deal with anything but the structural failure of a KISS - I've seen 2 inspos rendered useless on (expensive) trips because of niggly electrical faults.

<edit>

Scrubber - both are axial, more or less the same lime capacity (OK sports kiss isn't....). KISS is filled direct into gas path, Inspo uses a canister which is then inserted into gas path and uses seals to prevent bypass.

Lungs: classic KISS c/lungs are standard MSR bags available from the high street in 2,4,6... litre sizes. You can configure the KISS to have c/lung volume very close to your own lung volume which makes loop volume a doddle to maintain. Inspo c/lungs are again available in different sizes (& colours if you must) from APD to match the user. Inspo c/lungs also act as water traps and have dumps at bottom, KISS tends not to divert water into C/lungs and it collects at base of scrubber instead.

WOB: Inspo with OTC c/lungs maintains pretty constant WOB in all orientations. KISS WOB is v good in normal prone diving position, also OK when head down but more severe if you are ever on your back.

DSV: KISS has integrated OC/DSV so one lever takes you off the loop without taking anything out of your mouth. Inspo has a rotating barrel DSV which has to be closed and removed before going to any other gas. DYOR on CO2 hits and decide whether you would prefer an OC/DSV - this is available on the Inspo after market.
</edit>

There's a whole other chapter on failure modes, no time for that at the mo!

[Ken]

Originally Posted by The Purist

Back to your original question.... what's the difference between diving them? Well.... one person who could have answered that from 1st hand experience now can't (hint - RBW may be another place to ask this if you haven't already). One of the folks I dive with has moved from Inspo to KISS as well - I've been diving a KISS since 2001 and have a tiny bit of experience on the Inspo, so here's a blow by blow comparison based on my own experience - others may well have different opinions:

Setup: Both will need a similar amount of effort for cleaning, maintenance, assembly and checking. +/- checks, batteries etc are all much of a muchness. The Inspo can be disassembled without tools, the (classic) KISS requires you to have a small fettling box.

Pre-dive: The Inspo has a calibration routine that interprets the output of your cells - no such animal on the KISS, you have to tweak pots on the displays to calibrate them to air/100%. During the pre-breathe you can check the function of the inspo solenoid as well as the KISS valve. The Inspo will automatically maintain the low setpoint for you, whereas the KISS will require you to establish your own surface set-point.

Descent: The KISS has an ADV as standard, so descent is hands free, apart from checking the displays. AFAIK most people ride the Dil on the way down rather than trying for any particular setpoint. An Inspo without ADV requires manual Dil injection on descent to keep the c/lungs inflated but many users elect to fit an ADV. Inspo will maintain a setpoint on descent.

At bottom: Inspo is a switch to select higher set point, KISS has to manually inject O2 to achieve desired set point.


During dive: Inspo maintains set point (but handset checking still required) - KISS has O2 flow matched to metabolic rate (ish) so with a well set up KISS, in a steady state on a flat bottom you can go 10-15 mins without needing to touch the O2 (did a drift in the dark off Lulowrth back in Feb and thought my displays had frozen!). Expending effort or wobbly bottom profile can require more frequent O2 injection, but this is a reflex touch on the button with a handset check a few seconds later. Displays on the KISS are in an easy to check place (eft forearm), Inspo handsets tend to be clipped off so more work to look at them, but familiarity with your kit means that becomes easy.

Ascent - Inspo maintains set point again, KISS becomes a great tool for displaying the laws of physics as PO2 drops on ascent. Reality of this is that you adopt a different deco strategy as constant PO2 deco on the KISS is (1) a lot of work and (2) a waste of O2. Depending on your thoughts on deco you may prefer to avoid constant PO2 deco anyway, so perhaps not much to choose between them.

Surface - Again Inspo maintains PO2 whereas KISS can still have a go at you right up to the moment you spit the DSV when you're sat on the bench.

Maintenance - Jetsam's customer service has been second to none so far - when after spares (normally enhancements) Gordon has been known to ship before asking for payment. The whole 'evolution' of the KISS (sorry!) agaisnt the static state of the Inspo is IMHO partly due to the CE marking issue. Major changes to the Inspo will require resubmission, whereas the KISS can evolve as Gordon's mind devises better solutions. Everything to date has been backward compatible, so I could choose to upgrade mine to the latest spec if I really wanted to. AP are no slouches when it comes to service themselves HOWEVER one big difference is that you can stick enough spares in a small box to deal with anything but the structural failure of a KISS - I've seen 2 inspos rendered useless on (expensive) trips because of niggly electrical faults.

<edit>

Scrubber - both are axial, more or less the same lime capacity (OK sports kiss isn't....). KISS is filled direct into gas path, Inspo uses a canister which is then inserted into gas path and uses seals to prevent bypass.

Lungs: classic KISS c/lungs are standard MSR bags available from the high street in 2,4,6... litre sizes. You can configure the KISS to have c/lung volume very close to your own lung volume which makes loop volume a doddle to maintain. Inspo c/lungs are again available in different sizes (& colours if you must) from APD to match the user. Inspo c/lungs also act as water traps and have dumps at bottom, KISS tends not to divert water into C/lungs and it collects at base of scrubber instead.

WOB: Inspo with OTC c/lungs maintains pretty constant WOB in all orientations. KISS WOB is v good in normal prone diving position, also OK when head down but more severe if you are ever on your back.

DSV: KISS has integrated OC/DSV so one lever takes you off the loop without taking anything out of your mouth. Inspo has a rotating barrel DSV which has to be closed and removed before going to any other gas. DYOR on CO2 hits and decide whether you would prefer an OC/DSV - this is available on the Inspo after market.
</edit>

There's a whole other chapter on failure modes, no time for that at the mo!

Truly excellent summary. I'd like to use this piece sometime in the future for students comparing the YBOD and KISS! Cheers. Ken

[wreckweasel]

Ken,

theres a document on the KISS user site describing insp/kiss differences as well.

The chaps idea about fitting a KISS valve to an inspy has been done already by a certain well known fettler. It does indeed reduce your battery consumption, but it adds complexity in failure conditions. Most people think its more beneficial to conserve your batteries by manual flying your ECCR and using the electronics as a safety net.

/Zak

[RichClark]

Originally Posted by wreckweasel

Ken,

theres a document on the KISS user site describing insp/kiss differences as well.

/Zak

This would be interesting to read... any chance of pasting it here, or emailing it if it's too large.

Cheers

Rich

[Mark Chase]

Originally Posted by wreckweasel

Ken,

theres a document on the KISS user site describing insp/kiss differences as well.

The chaps idea about fitting a KISS valve to an inspy has been done already by a certain well known fettler. It does indeed reduce your battery consumption, but it adds complexity in failure conditions. Most people think its more beneficial to conserve your batteries by manual flying your ECCR and using the electronics as a safety net.

/Zak

Personally at £1.45 per battery I just stick new ones in roughly every 8 -10 hours of diving. Running the unit manually is a good idea if you have had a low battery warning in the water but apart from that it only takes 5mins to swap a battery before the dive.

I am aware that a lot of divers like to run the unit on a lower set point and fly it manually but I am baffled as to why they bothered getting and ECCR in the first place? The only argument I can understand is the diver being totally proficient at manually running the unit but personally if all my PP02 sensors are down Ill just bail out until I get to 6m.

ATB

Mark Chase