Question Hollis Prism 2 - Advice & Tips

[harveywalker500]

Hi all,

I was wanting to get into the silent world of rebreathers. I want to first start with recreational diving with them, before advancing through tech, I already have my Tec 40 and 45 from DSAT, but I would obviously get retrained for technical diving on a rebreather.

Obviously the cost of first getting into rebreathers is... high, so I wanted to do a "Discover Rebreather" type of class at a local dive shop. They offer and train on the Hollis Prism 2, which I've heard good things about (though I wouldn't know the specifics, the only thing about rebreathers I truly understand is how technical and somewhat dangerous they are).

For those who have dived with the Prism 2, what were your thoughts on the unit? Are they good to dive with? How compatible are they with other gear? Could I use the rebreather harness as a bp&w combo with a standard BCD?

Also to those who are experienced on rebreathers in general, would you say that, on a technical dive, the cost of the unit would be acceptable if I were to dive more frequently?

I appreciate my knowledge isn't the best but I appreciate all advice!

 

[211ratsbud]

For the cost of entry, The prism 2 is just as capable and certainly not hardware or software limited when comparing to the majority of the market share.

Compatibility with existing wings and BCDs is just like any set of doubles or similar setup. There is some obvious size constraints that should be considered such that you don't need probably a 60 lb wing and sometimes wings cannot be fitted properly due to their overall dimensions.

Many people dive 40 lb wings or plus or minus some and have good results.

The prism is limited to 3 l bottles only.
That shouldn't be an issue.
Usually you can find good deals on them use and even new.

I would consider that your instructor should be able to help you choose the path that helps you move forward most appropriately.

There are some things particularly about the prism that I disliked including the scrubber packing and assembly. These are not substandard and performance but substandard in my opinion, my very humble opinion, in preparation and assembly.

I think the prism had one of the best work of breathings ratings at one time if not still does.

Many people grow to accept the packing of the scrubber. It's more of a nuisance than anything.

And while I might change my decision because I can if you're in a position to get a good deal on one or get good training I wouldn't pass it up due to this little nuisance.

 

[rongoodman]

I trained on and owned one for a while and had no complaints. I sold it several years ago because I wasn't getting enough time on it to really stay current with it. It would have been great if I could have used it on the trips I've been diving since then.

 

[slimshady]

In my opinion the Prism 2 is one of th lightest abd smallest back mount CCRs. It was my first CCR and a good choice given the proximity of instructors, dive shop, and divers for training, service and support. I dove the unit for about 100 hours before getting a different CCR. I have or have owned and/or dove the Prism 2, KISS Sidewinder, Diverite Optima in backmount and chestmount, XCCR, and FXCCR.

You can use any backmount wing and backplate and I also saw a youtube where Jill Heinerth used a Katana 2 sidemount BCD with her Prism 2.

I had the backmount/shoulder counterlungs and the WOB was fine. I had one failure of one of the counterlungs covered under warranty.

I disliked the screw connections of loop hoses and T-pieces. The T-piece o-rings were prone to roll on mine. I second the opinion of 211Ratsbud about the scrubber. It is hard to pack, the screen stretches, and the screw on top is prone to collect hard sorb. Unlike my other CCRs, there are no springs to mitigate the settling of sorb that might occur although I never had a problem.

Also, the plastic cover over the clear plexiglass(?) scrubber cannister will get scratched easily and is not secure enough with the clip. Mine would fall off frequently and I made a velcro strap to hold it on.

As far as tech diving, the Prism 2 performed as well as my other units have on dives to 225 feet (75meters) on trimix. For caves the Prism 2 is taller when in horizontal trim than my other backmount units, even taller than a twinset, due to the plastic cover so maybe not the best unit for overhead.

 

[TuckerIdaho]

I've been diving a P2 for 1 1/2 years now. The scrubber is really its only weak point IMO. The key is to just set aside some time to pack the scrubber or you'll get frustrated and have threads full of sorb.

 

[rob1967]

I have been diving the Hollis Prism 2 for 10 years, and have over 500 dives on it. Needless to say, I know it very well. However, I don't have much to compare with, since I have very few dives on other CCR units. That being said, things I like about it are:
1. Reliable. I have had a few issues, but mostly my fault.
2. Work of breathing is good.
3. I don't mind the scrubber packing procedure. It is a bit finicky, but there is a YouTube video on how to pack it, and I got used to it quickly. I can now pack it in 5 minutes or so. I used to have a problem with sorb caking on the threads years ago when I used Intersorb 812 (Blue jug). However, that problem disappeared when I switched to Sofnolime Molecular (white jug).
4. I love the Shearwater electronics.
5. I like that it has a cover to protect the head.
6. Overall the unit is rugged.

Things I don't like are:
1. I find it is big and heavy and a pain to lug around. Literally a pain, because it is natural to grab it by the bar under the cover, and it pinches your fingers. I really need to look into some kind of carrying handle solution.
2. Lack of a stand. I should have bought one years ago.
3. Difficult to don. I think a stand will help with that.
4. Cover has frequently gotten cracked by various banging around, on the boat, under water, during travel. But at least the cover is relatively cheap to replace and protects the head.
5. I find it is a bit laborious to take it apart for cleaning and to put it together again. Particularly the screw-in for the hoses at the head, you need to keep putting lube on the threads on a regular basis, or it gets difficult to screw in and screw out. Bayonet mounts would likely be easier, but no way to change that.

Overall, I think it is a well-thought out and well-designed unit. I just wish it was lighter and more compact and easier to lug around.

 

[mr_v]

How often do you dive and why do you need a rebreather?

Most of us justify rebreather costs because "we can afford and want to dive rebreathers." But if you don't do at least 50-60 ~3hr dives per year, CC value becomes questionable.