Mares Horizon - few questions before the decision about course.

[Bartlomiej]

I have a chance to have refoundation for the course for Horizon (otherwise I would continue OC and same day maybe move to CCR). So please just answer my question and do not say "do not go into Horizon" .

1) What is the buoyancy of the deco version without tanks? I would calculate if I need to bring more weight when in twin.

2) In loop is always gas +-1% like in tank? My calculation: permanent addition 5l/min of EAN22 ->1,1 oxy l/min, during "normal" diving usage is 0.6 oxy l/min.

3) The suggested time for scrubber is 3h, it is SCR with 5 l/min donations, so if I use EAN22 (lowest recommended) it adds 5*0.22=1.1 l/min, normal usage for human is 0.6, so machine would not need to add more than this 5 l/min. 5*l/min * 180 min = 900l. 900l+ 25% =1200l. 1200l under the pressure of 200 bar gives 6l tank. 20min at 40m gives 20m deco, so deco tank and the bottom tank should be not bigger than 6l for one scrubber cycle?

4) What happened if I exceed the depth 40m. Of course, HUD would be red and the computer would scream "go up", but deco will be calculated correctly, and after dive I could make next with 24h blocked computer?

5) Should I call this two tank bailout or stage ? Generally, bailouts do not power reb.

Thanks for the help .

 

[grantctobin]

I have a chance to have refoundation for the course for Horizon (otherwise I would continue OC and same day maybe move to CCR). So please just answer my question and do not say "do not go into Horizon" .

1) What is the buoyancy of the deco version without tanks? I would calculate if I need to bring more weight when in twin.

2) In loop is always gas +-1% like in tank? My calculation: permanent addition 5l/min of EAN22 ->1,1 oxy l/min, during "normal" diving usage is 0.6 oxy l/min.

3) The suggested time for scrubber is 3h, it is SCR with 5 l/min donations, so if I use EAN22 (lowest recommended) it adds 5*0.22=1.1 l/min, normal usage for human is 0.6, so machine would not need to add more than this 5 l/min. 5*l/min * 180 min = 900l. 900l+ 25% =1200l. 1200l under the pressure of 200 bar gives 6l tank. 20min at 40m gives 20m deco, so deco tank and the bottom tank should be not bigger than 6l for one scrubber cycle?

4) What happened if I exceed the depth 40m. Of course, HUD would be red and the computer would scream "go up", but deco will be calculated correctly, and after dive I could make next with 24h blocked computer?

5) Should I call this two tank bailout or stage ? Generally, bailouts do not power reb.

Thanks for the help .

Minimum oxygen percentage in nitrox is 30% for the unit. I actually don’t think it’ll start flowing gas/let you start the dive if it analyzes less than that? As such, you can’t really take it to deeper than 40M. You also wouldn’t want to be at those depths without helium, which the Horizon doesn’t support.

Some people have pushed it a few minutes past it’s max deco lock out. The unit gets rather pissy when you do.

 

[Bernie_U]

1) Did a try-dive in a pool in an old worn 5mm wetsuit, which equals the buoyancy of a 3mm brand-new wetsuit. 6 kg of weight were loaded on the unit and I had no weight belt, still needed to add some air to the wing. So, I would guess that the Horizon is neutrally buoyant in water with 3 kg lead weight. My tanks were aluminium, so you can take that figure as 'without tanks'.

2) The oxygen fraction in the loop is controlled by the Horizon electronics. You enter the set-point, and the controller adds as much of gas as needed to meet the target. The manual explains that in detail, you can download from Mares.

3) In contrast to CCR diving, the Mares SCR is designed to be used with two tanks only. There is no small set of tanks for the rebreather and a large set of tanks for bailout. The size of the tanks has to be chosen on the gas calculation for the emergency case. If you plan to go 40m deep, a half-empty 6 L tank would not be safe in case you had to switch on OC. Design is for 2x 11 L (AL80).

4) User grantctobin already answered that.

5) Well, you can call it as you like. The manual says bottom gas cylinder and decompression cylinder.

 

[Rose Robinson]

1) Did a try-dive in a pool in an old worn 5mm wetsuit, which equals the buoyancy of a 3mm brand-new wetsuit. 6 kg of weight were loaded on the unit and I had no weight belt, still needed to add some air to the wing. So, I would guess that the Horizon is neutrally buoyant in water with 3 kg lead weight. My tanks were aluminium, so you can take that figure as 'without tanks'.

2) The oxygen fraction in the loop is controlled by the Horizon electronics. You enter the set-point, and the controller adds as much of gas as needed to meet the target. The manual explains that in detail, you can download from Mares.

3) In contrast to CCR diving, the Mares SCR is designed to be used with two tanks only. There is no small set of tanks for the rebreather and a large set of tanks for bailout. The size of the tanks has to be chosen on the gas calculation for the emergency case. If you plan to go 40m deep, a half-empty 6 L tank would not be safe in case you had to switch on OC. Design is for 2x 11 L (AL80).

4) User grantctobin already answered that.

5) Well, you can call it as you like. The manual says bottom gas cylinder and decompression cylinder.

Hello Bernie,

I'm detracting slightly from the OP's post, please accept my apologies, but I'm asking because I'm very curious and I'd like to know.

I have no familiarity with the Horizon, other than to have read the literature, and having viewed product videos.

My question is, if you're having to sling two AL80's, with the Horizon back-mounted unit, plus ballast to get the 3AL80's neutral, and taking into consideration, your diving the Horizon with NITROX, wouldn't you be just as well off, and thousands of dollars ahead by just diving with double steel 80's/100's, with NITROX and slinging one 3AL30/40, and needing no additional ballast?

I see no benefit in using the Horizon for this scenario, especially having to sling two 80's as your gaining nothing as far the reduced task loading benefit, which comes from diving with a rebreather and using using small tanks.

This question relates only to a 40m deep maximum.

Thank you in advance for your reply

Rose

 

[KenGordon]

Hello Bernie,

I'm detracting slightly from the OP's post, please accept my apologies, but I'm asking because I'm very curious and I'd like to know.

I have no familiarity with the Horizon, other than to have read the literature, and having viewed product videos.

My question is, if you're having to sling two AL80's, with the Horizon back-mounted unit, plus ballast to get the 3AL80's neutral, and taking into consideration, your diving the Horizon with NITROX, wouldn't you be just as well off, and thousands of dollars ahead by just diving with double steel 80's/100's, with NITROX and slinging one 3AL30/40, and needing no additional ballast?

I see no benefit in using the Horizon for this scenario, especially having to sling two 80's as your gaining nothing as far the reduced task loading benefit, which comes from diving with a rebreather and using using small tanks.

This question relates only to a 40m deep maximum.

Thank you in advance for your reply

Rose

You would take less gas. Two 80s would be more than necessary. The SCR ought to extend well over 3 times.

Really though, for shallow dives a twinset makes more sense and for deeper dives a proper CCR. There is a small window for dives which are shallow but long. I think this always kills SCR in the end. If you accept the electronics complications, cells risk and carrying bailout, you might as well go all the way.

It sort of looks cheap, half the price of a CCR, but...

 

[Rose Robinson]

You would take less gas. Two 80s would be more than necessary. The SCR ought to extend well over 3 times.

Really though, for shallow dives a twinset makes more sense and for deeper dives a proper CCR. There is a small window for dives which are shallow but long. I think this always kills SCR in the end. If you accept the electronics complications, cells risk and carrying bailout, you might as well go all the way.

It sort of looks cheap, half the price of a CCR, but...

Yes Ken,

And it looks like there's lots of buts.

Rose

 

[Asheron]

I have a chance to have refoundation for the course for Horizon (otherwise I would continue OC and same day maybe move to CCR). So please just answer my question and do not say "do not go into Horizon" .

1) What is the buoyancy of the deco version without tanks? I would calculate if I need to bring more weight when in twin.

2) In loop is always gas +-1% like in tank? My calculation: permanent addition 5l/min of EAN22 ->1,1 oxy l/min, during "normal" diving usage is 0.6 oxy l/min.

3) The suggested time for scrubber is 3h, it is SCR with 5 l/min donations, so if I use EAN22 (lowest recommended) it adds 5*0.22=1.1 l/min, normal usage for human is 0.6, so machine would not need to add more than this 5 l/min. 5*l/min * 180 min = 900l. 900l+ 25% =1200l. 1200l under the pressure of 200 bar gives 6l tank. 20min at 40m gives 20m deco, so deco tank and the bottom tank should be not bigger than 6l for one scrubber cycle?

4) What happened if I exceed the depth 40m. Of course, HUD would be red and the computer would scream "go up", but deco will be calculated correctly, and after dive I could make next with 24h blocked computer?

5) Should I call this two tank bailout or stage ? Generally, bailouts do not power reb.

Thanks for the help .

1) I wear 6lbs of lead with worthington hp100 doubles. I wear 34lbs of lead with the horizon.

2) You'll always run 32-36% eanx since you will metabolize 5-6%, which leaves a loop FO2 of 27-31%. The solenoid fires to maintain FO2 setpoint.

3) See attached charts.

4) Deco will be calculated. I do not believe it locks you out.

5)ehh.

Additional info:
Bailout Mode: when you bailout the system opens up the solenoid, so be aware when performing your drills you are flowing 5lpm +solenoid(30lpm?)+ breathing gas......it's a whole damn lot. Be quick about getting back into SCR mode.

Bailout during deco: with this unit interestingly if you plan for a contingency of unit failure you will always have enough gas for abort, and +10f/+5min. It is just such a hog when it opens the solenoid and dumps.

 

[broncobowsher]

Recreational rebreathers just never had a market. As mentioned such a narrow window where they shine.
If I remember the marketing correctly, the Horizon can later be upgraded to a full CCR (Mares branded rEvo). That is a huge step above the last attempt at mass produced recreational SCR rebreathers (Hollis Explorer).

 

[Tracy]

Recreational rebreathers just never had a market. As mentioned such a narrow window where they shine.
If I remember the marketing correctly, the Horizon can later be upgraded to a full CCR (Mares branded rEvo). That is a huge step above the last attempt at mass produced recreational SCR rebreathers (Hollis Explorer).

The Hollis explorer can be upgraded to an actual CCR. Kiss sells a drop in kit to make it less worthless.

 

[Wibble]

With a SCR there are some other benefits such as the gas bubbles not in the face which might be important for some people and it will be a lot quieter; fewer bubbles leaking out as the range extender cuts gas usage by 1/3 so less disturbing to animals; "unlimited gas" for heavy breathers (it'll be cycled by O2 depletion).

It "might" be easier to dive than a full CCR as it's ever so slightly less complex (no pure O2 for example). It should be marginally "safer" to dive as there's fewer controls to be confused by. The gas requirements are less difficult to source - basic nitrox is available through membrane compressors.

For those benefits, it is very much a recreational-level unit restricted to recreational depths and doesn’t support accelerated decompression with oxygen rich gasses (e.g. 80+%). The price is considerably more than the equivalent open circuit kit, even twinsets with deco stages. Being a rebreather, it’s far more complex to dive, buoyancy will be harder, flood issues and there's all the essential maintenance faff such as cleaning, building and scrubber packing.


Comparing an SCR to a full rebreather appears to have much of the pain for not too much gain.


The question is are there many people for whom those benefits are worth the effort of learning how to dive a rebreather that's so restricted in it's capabilities?