Prism II?

sunnyboy · 10th June 2008, 17:02

Hollis,

Great post. I think the PRISM counterlungs are absolutely fantastic. Sounds like you are doing good things with the design.

As I said, my biggest suggestion is to leave the recreational BCD concept behind. I personally still prefer the single webbing "Hog" harness over anything else I've used. I'm still not sure I'm convinced about using the counterlungs (or the backing) as harness straps - if only because it negates the "single webbing harness" concept, but I'll wait until I see the finished unit.

Mike - I think sidemount is great for bailout - I'm still refining mine. Maybe Hollis could offer sidemount as an option for the new Prism.

Cheers,

-S

silent running · 10th June 2008, 17:18

Quote: (Originally Posted by Mike)

I've had my unit for a few years now, and disagree. After doing ~50 hours with a standard backplate plus the counterlungs, including using under counterlung D-Rings, I decided that approach was harder to get into and out of, and conferred no benefits. So I've gone back to using the counterlungs as shoulderstraps, with a simple webbing waist band.

I sidemount bailout (up to 2 steel 12s or ali 80s) and don't need to clip off to the counterlungs at all. So the ease of getting into the unit with just the counterlungs is well worth it to my mind.
Mike

Hi Mike, I came to the same conclusion after using a standard BP and under the shoulder web straps/d-rings. I also went back to using the CL's as the weight baring part of the harness and had the velcro yoke sewn onto the top slots of a Deep Sea Supply plastic harness plate, right where the shoulder web straps would normally go. The Web belt gets threaded through the 2 lower CL loops and a single crotch strap, very simple and easy to get in and out of. I also use sidemount for BO as it's simple and the most stream-lined rigging I can think of and all works really well together. -Andy

***jradomski*** · 10th June 2008, 19:23

Quote: (Originally Posted by sunnyboy)

Hollis,

Great post. I think the PRISM counterlungs are absolutely fantastic. Sounds like you are doing good things with the design.

As I said, my biggest suggestion is to leave the recreational BCD concept behind. I personally still prefer the single webbing "Hog" harness over anything else I've used. I'm still not sure I'm convinced about using the counterlungs (or the backing) as harness straps - if only because it negates the "single webbing harness" concept, but I'll wait until I see the finished unit.

Mike - I think sidemount is great for bailout - I'm still refining mine. Maybe Hollis could offer sidemount as an option for the new Prism.

Cheers,

-S

For historical reference the "Prism" counterlungs came from another rebreather.. There were 3 or 4 versions of counterlungs designed for the UT-240, the PRISM lunges are nearly the same as the final version used on the UT-240, right down to the water dumps.. They were designed to be part of a specially designed "BC"

**Chett.L** · 10th June 2008, 20:25

Quote: (Originally Posted by Parker)

Just wondering if the Prism II is going to make the April 2008 ship date? And any other news that might be available on the unit?

Parker

Is there any word if the new Hollis Prism ll, parts will work on the existing Prism Topaz,

Like:
Hollis Oceanic First Stage Dil & Oxygen regulator, for better hose roughing.

Hollis, Dil add counter lung (probably not since the O2 and Dil bottles will be on the opposite side of Topaz?)

Hollis Prism ll BC

Chett. L

NEwreckdiver · 13th June 2008, 18:11

Yes, I would also like to hear what parts and support will be available for PRISM Topaz owners. On my list... sorry if these have already been asked...

I have heard a number of things RE the head .... you've changed the loop direction - OK - but what about the molding of the head? Are you installing the solenoid on the other side (which means molding changes) or are you routing the ss tubing around and just gluing in the triangle piece inside the head on the opposite side? Will you produce original configuration replacement heads for Topaz owners?

Scrubber basket and seating to the sealing gasket in the head - will whatever PRISM 2 does be compatible with the Topaz?

Bucket - Going from the bayonet style to latch style is a big change.... what about Topaz rigs and replacement buckets? This also relates to how the scrubber basket is attached... Is this something you really intend to change, and if so, what about Topaz owners?

Power switch - the one that comes from SMI is the weakest link of the whole unit. Are you planning to re-design or improve this? We need to have 3 switches and a bag of sliders to keep up with magnets rusting out for 2 rigs. Will these changes be compatible with the SMI rig?

You mention 90 degree angle fittings - have you looked at this to see how crowded it will be? Not a lot of space in there. Are there other changes that will be made to make 90 degree fittings work? Compatible with SMI rig?

ADV improvements... the strike plunger is too short and doesn't work well unless the CL is in "just" the right position - for me anyway. A simple change would be to make the plunger longer with like a mushroom shaped head to it. Planning to do this? Compatible with SMI rig?

I am very pleased to see Hollis produce the PRISM 2. I hope you have great success with it. It's a solid rig and I am happy with my choice of the PRISM - I would buy it again. However, whatever deal was struck between Hollis and SMI certainly seems like Hollis and SMI both got what they wanted, but the existing Topaz customers are potentially going to be stuck in some no-mans land with compatible parts or service with respect to any major changes re PRISM Topaz vs PRISM 2. If there are parts that won't be compatible and this goes back to "Buy what is compatible from Hollis and SMI will service those components that aren't" - then I am frightened for the future as a PRISM Topaz owner.

Heather Knowles

silent running · 13th June 2008, 20:39

Quote: (Originally Posted by Hollis)

Small diameter air passages have higher resistance to flow, or resistive effort. So do elbows, long tubes, flow direction mushroom valves, and thick scrubber beds. Using a sufficiently large diameter throughout the breathing loop, avoiding bends and elbows, using low durometer mushroom valves, and a radial scrubber all reduce resistive effort.

Hi Hollis, will you change anything in the Prism 2 loop, like say, smooth the interior of the elbows to get rid of the right angles? Also, If I'm not mistaken, there are hoses made which are corrugated on the outside but not on the inside, which should cut down on gas flow turbulence and possibly lower the resistive load further.

10th June 2008, 17:02	#21 (permalink)
sunnyboy RBW Member Current Rebreather/s: Prism Topaz Other Rebreather/s: Join Date: Feb 2006 Location: Ladysmith, B.C. Canada Posts: 98	Re: Prism II? Hollis, Great post. I think the PRISM counterlungs are absolutely fantastic. Sounds like you are doing good things with the design. As I said, my biggest suggestion is to leave the recreational BCD concept behind. I personally still prefer the single webbing "Hog" harness over anything else I've used. I'm still not sure I'm convinced about using the counterlungs (or the backing) as harness straps - if only because it negates the "single webbing harness" concept, but I'll wait until I see the finished unit. Mike - I think sidemount is great for bailout - I'm still refining mine. Maybe Hollis could offer sidemount as an option for the new Prism. Cheers, -S
(Offline)

10th June 2008, 17:18	#22 (permalink)
silent running Mature mouth breather Current Rebreather/s: Prism Topaz Other Rebreather/s: Join Date: Jun 2005 Location: U.S.A. Brooklyn, New York Posts: 1,873	Re: Prism II? Quote: (Originally Posted by Mike) I've had my unit for a few years now, and disagree. After doing ~50 hours with a standard backplate plus the counterlungs, including using under counterlung D-Rings, I decided that approach was harder to get into and out of, and conferred no benefits. So I've gone back to using the counterlungs as shoulderstraps, with a simple webbing waist band. I sidemount bailout (up to 2 steel 12s or ali 80s) and don't need to clip off to the counterlungs at all. So the ease of getting into the unit with just the counterlungs is well worth it to my mind. Mike Hi Mike, I came to the same conclusion after using a standard BP and under the shoulder web straps/d-rings. I also went back to using the CL's as the weight baring part of the harness and had the velcro yoke sewn onto the top slots of a Deep Sea Supply plastic harness plate, right where the shoulder web straps would normally go. The Web belt gets threaded through the 2 lower CL loops and a single crotch strap, very simple and easy to get in and out of. I also use sidemount for BO as it's simple and the most stream-lined rigging I can think of and all works really well together. -Andy
(Offline)

10th June 2008, 19:23	#23 (permalink)
*jradomski* Moderator Current Rebreather/s: Inspiration Classic Sport Kiss Optima rEvo Other CCR Other Rebreather/s: Inspiration Vision Evolution Megalodon Classic Kiss rEvo Other CCR Join Date: Mar 2005 Location: "Da" Bronx Posts: 3,113	Re: Prism II? Quote: (Originally Posted by sunnyboy) Hollis, Great post. I think the PRISM counterlungs are absolutely fantastic. Sounds like you are doing good things with the design. As I said, my biggest suggestion is to leave the recreational BCD concept behind. I personally still prefer the single webbing "Hog" harness over anything else I've used. I'm still not sure I'm convinced about using the counterlungs (or the backing) as harness straps - if only because it negates the "single webbing harness" concept, but I'll wait until I see the finished unit. Mike - I think sidemount is great for bailout - I'm still refining mine. Maybe Hollis could offer sidemount as an option for the new Prism. Cheers, -S For historical reference the "Prism" counterlungs came from another rebreather.. There were 3 or 4 versions of counterlungs designed for the UT-240, the PRISM lunges are nearly the same as the final version used on the UT-240, right down to the water dumps.. They were designed to be part of a specially designed "BC" __________________ Joe Radomski CCR Trimix Instructor Trainer ANDI Instructor Trainer Director #10 All posts are personal opinions and DO NOT reflect any affiliated agency unless specifically stated.
(Offline)

10th June 2008, 20:25	#24 (permalink)
Chett.L Supporting Member Current Rebreather/s: Prism Topaz Other Rebreather/s: Join Date: May 2007 Location: LOS ANGELES Posts: 406	Re: Prism II? Quote: (Originally Posted by Parker) Just wondering if the Prism II is going to make the April 2008 ship date? And any other news that might be available on the unit? Parker Is there any word if the new Hollis Prism ll, parts will work on the existing Prism Topaz, Like: Hollis Oceanic First Stage Dil & Oxygen regulator, for better hose roughing. Hollis, Dil add counter lung (probably not since the O2 and Dil bottles will be on the opposite side of Topaz?) Hollis Prism ll BC Chett. L __________________ Chett. L
(Online)

13th June 2008, 18:11	#25 (permalink)
NEwreckdiver RBW Member Current Rebreather/s: Prism Topaz Other Rebreather/s: Join Date: Oct 2005 Location: Boston MA Posts: 72	Re: Prism II? Yes, I would also like to hear what parts and support will be available for PRISM Topaz owners. On my list... sorry if these have already been asked... I have heard a number of things RE the head .... you've changed the loop direction - OK - but what about the molding of the head? Are you installing the solenoid on the other side (which means molding changes) or are you routing the ss tubing around and just gluing in the triangle piece inside the head on the opposite side? Will you produce original configuration replacement heads for Topaz owners? Scrubber basket and seating to the sealing gasket in the head - will whatever PRISM 2 does be compatible with the Topaz? Bucket - Going from the bayonet style to latch style is a big change.... what about Topaz rigs and replacement buckets? This also relates to how the scrubber basket is attached... Is this something you really intend to change, and if so, what about Topaz owners? Power switch - the one that comes from SMI is the weakest link of the whole unit. Are you planning to re-design or improve this? We need to have 3 switches and a bag of sliders to keep up with magnets rusting out for 2 rigs. Will these changes be compatible with the SMI rig? You mention 90 degree angle fittings - have you looked at this to see how crowded it will be? Not a lot of space in there. Are there other changes that will be made to make 90 degree fittings work? Compatible with SMI rig? ADV improvements... the strike plunger is too short and doesn't work well unless the CL is in "just" the right position - for me anyway. A simple change would be to make the plunger longer with like a mushroom shaped head to it. Planning to do this? Compatible with SMI rig? I am very pleased to see Hollis produce the PRISM 2. I hope you have great success with it. It's a solid rig and I am happy with my choice of the PRISM - I would buy it again. However, whatever deal was struck between Hollis and SMI certainly seems like Hollis and SMI both got what they wanted, but the existing Topaz customers are potentially going to be stuck in some no-mans land with compatible parts or service with respect to any major changes re PRISM Topaz vs PRISM 2. If there are parts that won't be compatible and this goes back to "Buy what is compatible from Hollis and SMI will service those components that aren't" - then I am frightened for the future as a PRISM Topaz owner. Heather Knowles
(Offline)

13th June 2008, 20:39	#26 (permalink)
silent running Mature mouth breather Current Rebreather/s: Prism Topaz Other Rebreather/s: Join Date: Jun 2005 Location: U.S.A. Brooklyn, New York Posts: 1,873	Re: Prism II? Quote: (Originally Posted by Hollis) Small diameter air passages have higher resistance to flow, or resistive effort. So do elbows, long tubes, flow direction mushroom valves, and thick scrubber beds. Using a sufficiently large diameter throughout the breathing loop, avoiding bends and elbows, using low durometer mushroom valves, and a radial scrubber all reduce resistive effort. Hi Hollis, will you change anything in the Prism 2 loop, like say, smooth the interior of the elbows to get rid of the right angles? Also, If I'm not mistaken, there are hoses made which are corrugated on the outside but not on the inside, which should cut down on gas flow turbulence and possibly lower the resistive load further.
(Offline)

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