Question Hollis Prism 2 - Advice & Tips

[iain/hsm]

I don't have a game in the Prism market... But the statement above is a load of BS. It makes me wonder if the author is a bot. To think of that, this is some serious load of garbage that typically comes from banned accounts.

ROFL You wish sunshine.

To kick off re the Prism for background. I have known Sharon and Peter Readey for some time now back when he lived in Warrington and when they lived down in Cornwall when they introduced me to the best crispy beef I have ever had.
Back then BOTS didn't exist but amateur stunt divers did together with there BS and by the looks of things they still do. But no matter.

Back then I was also involved in other diving design projects and with a chap called Stuart Clough who together with Peter we added together our initials PR SC IM and I wrote a letter to Peter of the suggestion of PRISM as bots and email didn't exist back.

The original concept was for a modification of the then CCR 155 / Mk15b for use in remote areas diving for deep spidge (and the Santa Maria del la Rosa) but no matter on that part. Smith Kline Beecham came along and diving for plant life became the goal of both Peter and Stuart.

They flew over to see us here last year in the sunny Cotswolds then drove over to see Stuart Clough. Sharon explained the things that were forgotten and buried and set a panic in motion as they had a plan to write a book. I spoke with Stuart only last week by email would you believe we have email now we just don't talk about Peters book. But judging by the sounds of things you're not going to like.

So we can raise the dead later if you like.

Happy days from the author. A Bot formally known as Iain ROFL

 

[mr_v]

Ok, you're right, you're not a bot. Bots do better context and logic flows.

 

[telemonster]

Also: I hate anything beeping or vibrating, so I consider that a feature that they don't. I think rebreather divers must be situationally aware enough to monitor their controllers. First thing I did when I got my first Petrel 3 was turn off ALL vibration.

I get that, I dive my prism2 somewhat manually doing my own o2 additions trying to beat the computer to any solenoid injection. But I always felt that in some extreme edge case having that alert could be a saver. I guess it would be really annoying when ascending near surface and ppo2 drops.

Any other prism2 divers on here, do you mod the o2 manual addition for a higher flow rate or run it stock?

 

[211ratsbud]

I get that, I dive my prism2 somewhat manually doing my own o2 additions trying to beat the computer to any solenoid injection. But I always felt that in some extreme edge case having that alert could be a saver. I guess it would be really annoying when ascending near surface and ppo2 drops.

Any other prism2 divers on here, do you mod the o2 manual addition for a higher flow rate or run it stock?

I used a spare dil-mav for my oxygen injection during a decompression based training. It prevents suffocating during an oxygen flush

 

[211ratsbud]

Also a good heads up is the IQ sub t-pieces are compatible with the prism ports. You can delete the adv this way, or even use the better one from IQ sub if you'd like.

 

[EricSm]

I've got a Prism 2 and by background am a Marine Engineer so will share from that perspective. The unit has been reliable for me (except the DSV is a complete POS if you do that instead of the BOV). It leaked air after the first few dives and could be rectified even with cleaning and tightening down the resistance to the point it became a BOV. The Prism 2 is CE approved (if that is important to you), but the DSV is not.

I think the biggest factor, that several talked around, is availability of local support and an accessible instructor. A rebreather isn't a catalog item that you go get serviced wherever like a regulator. I was interested in a Megalodon, but chose the Prism based on availability and satisfaction with the local instructor. Having seen both now, the Megalodon is a lot smaller/ more compact, but I don't really regret choosing the Prism 2 over the Megalodon. They relative availability of the Prism 2 means that when dive buddies have had an issue whether scrubber basket or whatever they have been able to go to a Hollis dealer in a remote location (if Bonaire is remote) and buy or borrow a spare part to make the dives.

I went went with the front mount counter lungs, which make venting gas when surfacing much less of a hassle vs the back mount counter lungs. Cleaning the unit is also easier with the front mount counter lungs. I didn't get a lot of guidance on one vs the other when deciding, but think I chose wisely.

The hoses that thread into the head and where they screw onto the counter-lungs is temperamental, but something that you get more accustomed to with time. It should have been designed better. I put a scubapro stainless backplate on mine (I copied that idea) so I have a handle to move the unit around. My other Prism 2 dive buddies are moving to the the scubapro stainless backplate too. The stand is mandatory and I think just comes with it now. All the CCR's are roughly the same money ~10k (except the Divesoft Liberty ~15k) so you aren't really shopping based on price. My biggest gripe with the Prism is the frame is aluminum and bolted directly to a stainless backplate... it is just an anode. Aluminum shouldn't be used in seawater (except as a sacrificial anode) and certainly not bolted directly to stainless. My next CCR (some years down the road) I am thinking about an XCCR with larger scrubber, tank options other then 3 liter, bayonet fittings for the hoses, still uses Shearwater electronics and does not use aluminum. Availability of local support is an issue though.

 

[gordonscuba]

My biggest gripe with the Prism is the frame is aluminum and bolted directly to a stainless backplate... it is just an anode. Aluminum shouldn't be used in seawater (except as a sacrificial anode) and certainly not bolted directly to stainless.

That is 100% true. Luckily, Hollis makes a stainless steel H-frame with the same dimensions as the AL frame. I picked one up for about $200 if I recall correctly. This completely removed the galvanic corrosion issue, so if that's your biggest gripe, it's a $200 fix.

Of course switching the H-frame from AL to SS adds a couple pounds of weight. In warm tropical water, I am typically overweighted on the SF2 or P2 even without adding any lead. I started using the Halcyon carbon fiber backplate which reduced weight by about 5 lbs, and a Titanium stand which shaved off another pound. That's a good first step but still somewhat overweighted.

Having a solid handle at the top of the unit is very helpful. Most backplates don't provide one. Luckily there are small holes in the top of the H-frame that aren't used for anything, and are perfect for bolting on a small steel handle (see pic).

 

[rob1967]

That is 100% true. Luckily, Hollis makes a stainless steel H-frame with the same dimensions as the AL frame. I picked one up for about $200 if I recall correctly. This completely removed the galvanic corrosion issue, so if that's your biggest gripe, it's a $200 fix.

Of course switching the H-frame from AL to SS adds a couple pounds of weight. In warm tropical water, I am typically overweighted on the SF2 or P2 even without adding any lead. I started using the Halcyon carbon fiber backplate which reduced weight by about 5 lbs, and a Titanium stand which shaved off another pound. That's a good first step but still somewhat overweighted.

Having a solid handle at the top of the unit is very helpful. Most backplates don't provide one. Luckily there are small holes in the top of the H-frame that aren't used for anything, and are perfect for bolting on a small steel handle (see pic).

Any advice on where to get a stainless steel handle that would fit on to the top of the H-frame?

 

[sea_ledford]

Any other prism2 divers on here, do you mod the o2 manual addition for a higher flow rate or run it stock?

I run mine stock. Just finished my 100m class and the reduced flow is great at depth. In the shallows, I'm not a fan. Especially when trying to flush out all the off gassing and I'm deeply exhaling AND dumping the lungs. It feels like 30 seconds before I can breathe again...

 

[gordonscuba]

Any advice on where to get a stainless steel handle that would fit on to the top of the H-frame?

Sure. Contact Marek Bochniak, he makes them and sells them, along with some other useful items like a wider stand. Marek's website is the following:

Home - Prism2CCR - Kursy nurkowe

Hollis Prism 2 CCR Kursy nurkowe Doskonal swoje umiejętności i rozszerz horyzonty podwodnego świata dzięki zaawansowanej technologii zamkniętego obiegu. Wydłuż czas nurkowania, kontroluj dekompresję i ciesz się niezrównaną mobilnością. Odkryj nowe możliwości nurkowania z Hollis Prism2 CCR...

prism2ccr.pl

Also consider joining a facebook group called "Hollis Prism 2 Rebreather Divers" on which you can find some of Marek's posts and probably DM him about placing orders. That group is also just, in general, a good place to get questions answered -- several of the members are P2 instructors with 1000+ dives on the unit.