Hollis Explorer rebreather

[MichaelS.]

That is good to here! The dive log software is coming around dema time so things are looking great.

 

[Douglas Ward]

I've got some updates on the Explorer.

I've been diving mine since Aug.

1) Scrubber Duration: while advertised at 2 hours, this is not reality. The scrubber duration was never more than 83 minutes. Most recently in warm easy diving conditions, it only allowed 45 minutes.
2) There has been constant communication cable failures along with Wireless HP sending unit connection issues.
3) There have been several instances of error codes with no explanation that simply direct you to return the unit to manufacturer but then allow you to complete a Successful Pre-Dive.
4) Currently the Logbook on the computer won't record dives
5) Dive planning is completely impractical since the PO2 is constantly fluctuating and you have no control over it.
6) The computer gives HP usage warnings anytime use use the BC inflator even a little bit (more of an annoyance really).

It's also worth noting that anyone with a decent SAC rate on an AL80 would match or beat the performance of the Explorer, so you really have no motivation to assume the added task load or risk of diving a rebreather over OC. Also if you decide to change to open circuit the same day because of the previously noted issues, it makes planning that dive very tricky since you really have no idea what you residual N loading is or what your follow up NDL's should be.

The unit has been returned to Hollis to correct the scrubber life issue. But the returned unit performs worse than when it was sent to them.

My opinion is that the Explorer has the potential to be a great bridge unit between open circuit and CCR, but the controller and computer have a long way to go before it's gonna be ready for prime time. I hope Hollis works out the bugs. I like the idea of the Explorer, but it's just not ready.

 

[HIGHwing]

I've dove a couple Explorers and can say without a doubt the unit is far underperforming expectations.

In fact, I would argue that a diver who is diving equivalent Nitrox mix OC versus an Explorer diver has a [significant] decompression advantage on all dives. This unit successfully reduces comparative NDL, costs more to operate, the scrubber doesn't last as long as most divers with an AL80, and for all those disadvantages you gain 2/3s of the risk of a CCR (it's essentially impossible to tox). I evaluate the Hollis Explorer in its current state as a risk enhancer and dive time reducer. I actually think Hollis should announce a voluntary recall and take a very serious look at the software running on the handset prior to allowing inexperienced closed circuit divers access to the machines.

I cancelled my order, cancelled my instructor x-over class, and suggested my dive buddies look elsewhere in rebreather technology .

 

[darushin]

My experience with unit. Scrubber life will meet expectations when you do two things. First you use nitrox 40 and second turn the dcp down from 95 to 50. This lower dcp means a little less ndl (my exp is it still matches nitrox 36). The higher nitrox means less shots of air from the solenoid which means less clicks on the click counter that is also used to measure CO2 absorbent. I can get 2hrs using the above settings with a CO2 sensor. Ultimately, this unit may work with nitrox 32 but the unit really was designed for nitrox 40

Dar

 

[HIGHwing]

I can get 2hrs using the above settings with a CO2 sensor.

Can you post the dive profile(s) showing 120 minutes of dive time where you did not add scrubber or gas to the machine? I'd love to see how you achieved such a feat. We've spent months trying to figure out how to reliably get even an hour out of the scrubber at any reasonable depth. So far in our testing, I've been able to beat the available bottom time of the Explorer with an AL80 no matter the depth/profile/temp combination assuming same FO2 is in 5L on the Explorer and the AL80 on my back.

 

[TheTrickster]

Ultimately, this unit may work with nitrox 32 but the unit really was designed for nitrox 40

Which, from all the places I've dived at, Nitrox32 is the norm.

Its not sounding that great for the unit, hoping that it works out in the end.

 

[Douglas Ward]

I've dived the Explorer with 40 percent 32 percent 35 percent in multiple temperatures of waters from 80 degree to 46 degrees with DCP settings from 10 to 95 & automatic.

Scrubber will not reach 120 minutes.

The only I could see it ever happening is with the DCP on 10 40% Nitrox 80 degree water in about 10 to 20 feet of water.

So basically a pool.

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[darushin]

Can you post the dive profile(s) showing 120 minutes of dive time where you did not add scrubber or gas to the machine? I'd love to see how you achieved such a feat. We've spent months trying to figure out how to reliably get even an hour out of the scrubber at any reasonable depth. So far in our testing, I've been able to beat the available bottom time of the Explorer with an AL80 no matter the depth/profile/temp combination assuming same FO2 is in 5L on the Explorer and the AL80 on my back.

Unfortunately I can't post the log of the computer because I have cleared it because I currently have the unit up for sale. I do remember the two hours were achieved at Hudson Grotto in Florida a few weeks ago with depths ranging between 25-45 feet and was done over two dives lasting about 50-55 minutes each with no scrubber or tank changes. At the end of the dive 2 the unit reported appx 15-20 minutes of scrubber life.

I used 40/15 with dcp at 10%.

Daru

 

[Douglas Ward]

Dar,

Trimix in the explorer? Interesting.

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[darushin]

Yes I use 15% in it. That doesn't affect the ndls any and for me the narcosis reduction and the slightly easier breathing makes for a good trade off

Daru

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