From personal_submersibles at psubs.org Thu Jan 22 16:32:17 2026 From: personal_submersibles at psubs.org (Rick Patton via Personal_Submersibles) Date: Thu, 22 Jan 2026 11:32:17 -1000 Subject: [PSUBS-MAILIST] second stage adjusting Message-ID: I had shared about a thruster leaking on my first dip. Someone in the group said that they had adjusted their second stage for more positive pressure. I am not sure how to do that. Rick -------------- next part -------------- An HTML attachment was scrubbed... URL: From personal_submersibles at psubs.org Thu Jan 22 17:06:51 2026 From: personal_submersibles at psubs.org (via Personal_Submersibles) Date: Thu, 22 Jan 2026 23:06:51 +0100 Subject: [PSUBS-MAILIST] second stage adjusting In-Reply-To: References: Message-ID: <00ec01dc8beb$69c0ca10$3d425e30$@airesearch.nl> Hi Rick, Maybe a open door but the (vertical) position makes also a difference. Some 10-20?lower than the thruster will create overpressure. However, it should be tight without overpressure. Br, Emile Van: Personal_Submersibles Namens Rick Patton via Personal_Submersibles Verzonden: donderdag 22 januari 2026 22:32 Aan: psubs chat room Onderwerp: [PSUBS-MAILIST] second stage adjusting I had shared about a thruster leaking on my first dip. Someone in the group said that they had adjusted their second stage for more positive pressure. I am not sure how to do that. Rick -------------- next part -------------- An HTML attachment was scrubbed... URL: From personal_submersibles at psubs.org Thu Jan 22 18:58:16 2026 From: personal_submersibles at psubs.org (Jon Wallace via Personal_Submersibles) Date: Thu, 22 Jan 2026 23:58:16 +0000 (UTC) Subject: [PSUBS-MAILIST] USCG update References: <165715359.3391203.1769126296981.ref@mail.yahoo.com> Message-ID: <165715359.3391203.1769126296981@mail.yahoo.com> Gentlemen, The USCG has declined our invitation to attend the 2026 convention citing a restriction on attending conferences.? See the following quoted text which is the entirety of their response: "Thank you for the invitation, however unfortunately we are no longer permitted to attend conferences.? As we previously discussed we are not looking to add additional regulations to recreational submersibles at this time.? If that ever changes, we will make sure we reach out to PSubs for their involvement." While I am disappointed the USCG will not be attending, this email and discussions I have had with USCG personnel in Washington HQ, do seem to suggest that there are no impending regulations that will impact us, or our organization, in the foreseeable future.? While that is great news it is even more incumbent upon us to ensure we continue to design, fabricate, and operate safely, and adhere to industry standards as set by ABS, ASME, and ourselves.? In this way, we will continue to maintain our reputation and preserve our rights to enjoy our hobby with minimal government interference. In the meantime, I feel this was a missed opportunity by the USCG that?risks reinforcing the perception that the private submersible community?s expertise and concerns are not being given due consideration.? For that reason, I am drafting a letter to the USCG Commandant respectfully expressing our disappointment and planting a seed for reconsideration in the future. Jon From personal_submersibles at psubs.org Thu Jan 22 22:51:47 2026 From: personal_submersibles at psubs.org (subvet596 via Personal_Submersibles) Date: Thu, 22 Jan 2026 22:51:47 -0500 Subject: [PSUBS-MAILIST] USCG update In-Reply-To: <165715359.3391203.1769126296981@mail.yahoo.com> Message-ID: <6972EF9300000974@altprdrgo001.altice.prod.cloud.openwave.ai> (added by postmaster@optonline.net) I suggest that you don't poke the bear.John K.(203) 414-1000Sent via the Samsung Galaxy S10e, an AT&T 5G Evolution capable smartphone -------- Original message --------From: Jon Wallace via Personal_Submersibles Date: 1/22/26 10:30 PM (GMT-05:00) To: Personal Submersibles General Discussion Subject: [PSUBS-MAILIST] USCG update Gentlemen,The USCG has declined our invitation to attend the 2026 convention citing a restriction on attending conferences.? See the following quoted text which is the entirety of their response:"Thank you for the invitation, however unfortunately we are no longer permittedto attend conferences.? As we previously discussed we are not looking to addadditional regulations to recreational submersibles at this time.? If thatever changes, we will make sure we reach out to PSubs for their involvement."While I am disappointed the USCG will not be attending, this email and discussions I have had with USCG personnel in Washington HQ, do seem to suggest that there are no impending regulations that will impact us, or our organization, in the foreseeable future.? While that is great news it is even more incumbent upon us to ensure we continue to design, fabricate, and operate safely, and adhere to industry standards as set by ABS, ASME, and ourselves.? In this way, we will continue to maintain our reputation and preserve our rights to enjoy our hobby with minimal government interference.In the meantime, I feel this was a missed opportunity by the USCG that?risks reinforcing the perception that the private submersible community?s expertise and concerns are not being given due consideration.? For that reason, I am drafting a letter to the USCG Commandant respectfully expressing our disappointment and planting a seed for reconsideration in the future.Jon_______________________________________________Personal_Submersibles mailing listPersonal_Submersibles at psubs.orghttp://www.psubs.org/mailman/listinfo.cgi/personal_submersibles -------------- next part -------------- An HTML attachment was scrubbed... URL: From personal_submersibles at psubs.org Thu Jan 22 23:04:01 2026 From: personal_submersibles at psubs.org (via Personal_Submersibles) Date: Fri, 23 Jan 2026 04:04:01 +0000 (UTC) Subject: [PSUBS-MAILIST] USCG update In-Reply-To: <6972EF9300000974@altprdrgo001.altice.prod.cloud.openwave.ai> References: <165715359.3391203.1769126296981@mail.yahoo.com> <6972EF9300000974@altprdrgo001.altice.prod.cloud.openwave.ai> Message-ID: <701787884.2006475.1769141041891@mail.yahoo.com> Jon, I notice the USCG response was in the passive voice.? Perhaps some there think it best to not stir up internal discussions with those who might have a more controlling mindset.? Whoever attends would certainly be required to file a written report for review and critique. Jim T. In a message dated 1/22/2026 9:50:02 PM Central Standard Time, personal_submersibles at psubs.org writes:? I suggest that you don't poke the bear.?John K.(203) 414-1000???Sent via the Samsung Galaxy S10e, an AT&T 5G Evolution capable smartphone??-------- Original message --------From: Jon Wallace via Personal_Submersibles Date: 1/22/26 10:30 PM (GMT-05:00)To: Personal Submersibles General Discussion Subject: [PSUBS-MAILIST] USCG update?Gentlemen, The USCG has declined our invitation to attend the 2026 convention citing a restriction on attending conferences.? See the following quoted text which is the entirety of their response: "Thank you for the invitation, however unfortunately we are no longer permitted to attend conferences.? As we previously discussed we are not looking to add additional regulations to recreational submersibles at this time.? If that ever changes, we will make sure we reach out to PSubs for their involvement." While I am disappointed the USCG will not be attending, this email and discussions I have had with USCG personnel in Washington HQ, do seem to suggest that there are no impending regulations that will impact us, or our organization, in the foreseeable future.? While that is great news it is even more incumbent upon us to ensure we continue to design, fabricate, and operate safely, and adhere to industry standards as set by ABS, ASME, and ourselves.? In this way, we will continue to maintain our reputation and preserve our rights to enjoy our hobby with minimal government interference. In the meantime, I feel this was a missed opportunity by the USCG that?risks reinforcing the perception that the private submersible community?s expertise and concerns are not being given due consideration.? For that reason, I am drafting a letter to the USCG Commandant respectfully expressing our disappointment and planting a seed for reconsideration in the future. Jon _______________________________________________ Personal_Submersibles mailing list Personal_Submersibles at psubs.org http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles_______________________________________________ Personal_Submersibles mailing list Personal_Submersibles at psubs.org http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles -------------- next part -------------- An HTML attachment was scrubbed... URL: From personal_submersibles at psubs.org Thu Jan 22 23:35:25 2026 From: personal_submersibles at psubs.org (Rick Patton via Personal_Submersibles) Date: Thu, 22 Jan 2026 18:35:25 -1000 Subject: [PSUBS-MAILIST] second stage adjusting In-Reply-To: <00ec01dc8beb$69c0ca10$3d425e30$@airesearch.nl> References: <00ec01dc8beb$69c0ca10$3d425e30$@airesearch.nl> Message-ID: Hi Emile, not sure what you mean by open door? My second stage is probably 18" to 24" lower than the thrusters but someone in the group said that he had adjusted his second stage I thought to more over bottom pressure than how they come off the shelf. Rick On Thu, Jan 22, 2026 at 12:07?PM via Personal_Submersibles < personal_submersibles at psubs.org> wrote: > Hi Rick, > > > > Maybe a open door but the (vertical) position makes also a difference. > Some 10-20?lower than the thruster will create overpressure. > > However, it should be tight without overpressure. > > > > Br, Emile > > > > *Van:* Personal_Submersibles *Namens > *Rick Patton via Personal_Submersibles > *Verzonden:* donderdag 22 januari 2026 22:32 > *Aan:* psubs chat room > *Onderwerp:* [PSUBS-MAILIST] second stage adjusting > > > > I had shared about a thruster leaking on my first dip. Someone in the > group said that they had adjusted their second stage for more positive > pressure. I am not sure how to do that. > > > > Rick > _______________________________________________ > Personal_Submersibles mailing list > Personal_Submersibles at psubs.org > http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles > -------------- next part -------------- An HTML attachment was scrubbed... URL: From personal_submersibles at psubs.org Fri Jan 23 05:45:55 2026 From: personal_submersibles at psubs.org (via Personal_Submersibles) Date: Fri, 23 Jan 2026 11:45:55 +0100 Subject: [PSUBS-MAILIST] second stage adjusting In-Reply-To: References: <00ec01dc8beb$69c0ca10$3d425e30$@airesearch.nl> Message-ID: <012401dc8c55$73d5c310$5b814930$@airesearch.nl> Hi Rick, I meant that this is probably know to you. Proverbs translate not very well ? Br, Emile Van: Personal_Submersibles Namens Rick Patton via Personal_Submersibles Verzonden: vrijdag 23 januari 2026 05:35 Aan: Personal Submersibles General Discussion Onderwerp: Re: [PSUBS-MAILIST] second stage adjusting Hi Emile, not sure what you mean by open door? My second stage is probably 18" to 24" lower than the thrusters but someone in the group said that he had adjusted his second stage I thought to more over bottom pressure than how they come off the shelf. Rick On Thu, Jan 22, 2026 at 12:07?PM via Personal_Submersibles > wrote: Hi Rick, Maybe a open door but the (vertical) position makes also a difference. Some 10-20?lower than the thruster will create overpressure. However, it should be tight without overpressure. Br, Emile Van: Personal_Submersibles > Namens Rick Patton via Personal_Submersibles Verzonden: donderdag 22 januari 2026 22:32 Aan: psubs chat room > Onderwerp: [PSUBS-MAILIST] second stage adjusting I had shared about a thruster leaking on my first dip. Someone in the group said that they had adjusted their second stage for more positive pressure. I am not sure how to do that. Rick _______________________________________________ Personal_Submersibles mailing list Personal_Submersibles at psubs.org http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles -------------- next part -------------- An HTML attachment was scrubbed... URL: From personal_submersibles at psubs.org Fri Jan 23 08:23:16 2026 From: personal_submersibles at psubs.org (hank pronk via Personal_Submersibles) Date: Fri, 23 Jan 2026 13:23:16 +0000 (UTC) Subject: [PSUBS-MAILIST] second stage adjusting In-Reply-To: <012401dc8c55$73d5c310$5b814930$@airesearch.nl> References: <00ec01dc8beb$69c0ca10$3d425e30$@airesearch.nl> <012401dc8c55$73d5c310$5b814930$@airesearch.nl> Message-ID: <668159612.1443225.1769174596049@mail.yahoo.com> Hi Rick, I use a first stage regulator with the spring removed to act as the pressure compensator. ?I use a first stage to bring down the pressure from the tank as normal, then send that air to the second first stage regulatow with spring removed, then to the motors. ?The output pressure to the motor is a constant 2 psi or so. ?I tie all the motors and arm to the one regulator. ?I have had no luck with the scuba second stage regulator set up. ?Tested to 400 feet, no issues.Hank On Friday, January 23, 2026 at 03:46:07 AM MST, via Personal_Submersibles wrote: Hi Rick, ? I meant that this is probably know to you. Proverbs translate not very well? ? ? Br, Emile ? Van: Personal_Submersibles Namens Rick Patton via Personal_Submersibles Verzonden: vrijdag 23 januari 2026 05:35 Aan: Personal Submersibles General Discussion Onderwerp: Re: [PSUBS-MAILIST] second stage adjusting ? Hi Emile, not sure what you mean by open door? My second stage is probably 18" to 24" lower than the thrusters but someone in the group said that he had adjusted his second stage I thought to more over bottom pressure than how they come off the shelf. ? Rick ? On Thu, Jan 22, 2026 at 12:07?PM via Personal_Submersibles wrote: Hi Rick, ? Maybe a open door but the (vertical) position makes also a difference. Some 10-20?lower than the thruster will create overpressure. However, it should be tight without overpressure. ? Br, Emile ? Van: Personal_Submersibles Namens Rick Patton via Personal_Submersibles Verzonden: donderdag 22 januari 2026 22:32 Aan: psubs chat room Onderwerp: [PSUBS-MAILIST] second stage adjusting ? I had shared about a thruster leaking on my first dip. Someone in the group said that they had adjusted their?second stage for more positive pressure. I am not sure how to do that. ? Rick _______________________________________________ Personal_Submersibles mailing list Personal_Submersibles at psubs.org http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles _______________________________________________ Personal_Submersibles mailing list Personal_Submersibles at psubs.org http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles -------------- next part -------------- An HTML attachment was scrubbed... URL: From personal_submersibles at psubs.org Fri Jan 23 11:48:05 2026 From: personal_submersibles at psubs.org (Jon Wallace via Personal_Submersibles) Date: Fri, 23 Jan 2026 16:48:05 +0000 (UTC) Subject: [PSUBS-MAILIST] second stage adjusting In-Reply-To: <668159612.1443225.1769174596049@mail.yahoo.com> References: <00ec01dc8beb$69c0ca10$3d425e30$@airesearch.nl> <012401dc8c55$73d5c310$5b814930$@airesearch.nl> <668159612.1443225.1769174596049@mail.yahoo.com> Message-ID: <1300040415.1256452.1769186885100@mail.yahoo.com> How do you release pressure from the motors when surfacing? On Friday, January 23, 2026 at 08:25:20 AM EST, hank pronk via Personal_Submersibles wrote: Hi Rick, I use a first stage regulator with the spring removed to act as the pressure compensator. ?I use a first stage to bring down the pressure from the tank as normal, then send that air to the second first stage regulatow with spring removed, then to the motors. ?The output pressure to the motor is a constant 2 psi or so. ?I tie all the motors and arm to the one regulator. ?I have had no luck with the scuba second stage regulator set up. ?Tested to 400 feet, no issues. Hank From personal_submersibles at psubs.org Fri Jan 23 12:40:18 2026 From: personal_submersibles at psubs.org (Alan James via Personal_Submersibles) Date: Fri, 23 Jan 2026 17:40:18 +0000 (UTC) Subject: [PSUBS-MAILIST] second stage adjusting In-Reply-To: References: Message-ID: <61197843.1533855.1769190018906@mail.yahoo.com> Rick,I resin printed a second stage regulator bodywith an adjustment bolt & spring to give up to 10psi overpressure. It has a diagphram rated for 80psi that was built for me in China & a standard 2nd stage mechanism for regulating air.It has an outlet fitting to an 8 port manifold.On the manifold I have an over- pressure valve for pressure relief in the system.I am building an electric manipulator & using the compensator for that as well as the thrusters.Hanks method of using an additional 1st stage should work. I believe Karl Stanley is or was using this method. He said he let the over- pressure bubble out through the thruster o-rings.Not sure what type of 1st stage Hank is using.Possibly the more sensitive diaphragm type.You could run a line from the first stage to a manifold and put a beer brewing type over- pressure valve in the manifold. Not sure how long the spring in the manifold will last though. I think they are 304 stainless.Cheers. Yahoo Mail: Search, organise, conquer -------------- next part -------------- An HTML attachment was scrubbed... URL: From personal_submersibles at psubs.org Fri Jan 23 13:28:17 2026 From: personal_submersibles at psubs.org (John Bussard via Personal_Submersibles) Date: Fri, 23 Jan 2026 10:28:17 -0800 Subject: [PSUBS-MAILIST] USCG update In-Reply-To: <701787884.2006475.1769141041891@mail.yahoo.com> References: <701787884.2006475.1769141041891@mail.yahoo.com> Message-ID: <6CC3F31D-01BB-4F06-A4D3-2A416B852528@gmail.com> An HTML attachment was scrubbed... URL: From personal_submersibles at psubs.org Fri Jan 23 13:43:26 2026 From: personal_submersibles at psubs.org (River Dolfi via Personal_Submersibles) Date: Fri, 23 Jan 2026 13:43:26 -0500 Subject: [PSUBS-MAILIST] USCG update Message-ID: Jon, I wouldn't interpret the USCG backing out as a snub. DOGE hit the federal workforce pretty hard with restrictions on what was deemed "unnecessary" travel. The civilian workforces for NAVSEA and the USCG somehow drew the most ire out of the entire DOD. My NAVSEA contracting officer had his NAVSEA travel expense card set to a $1 limit (as did everyone else in the federal government) while deployed to Japan to manage a Navy salvage project. I wouldn't describe any of that as "frivolous" or "unnecessary" but here we are. Thankfully the heat has cooled down some, but I imagine a Florida Keys junket for such a niche issue would be hard to justify to the beancounters. Thanks, -River J. Dolfi rdolfi7 at gmail.com -------------- next part -------------- An HTML attachment was scrubbed... URL: From personal_submersibles at psubs.org Fri Jan 23 14:02:43 2026 From: personal_submersibles at psubs.org (Rick Patton via Personal_Submersibles) Date: Fri, 23 Jan 2026 09:02:43 -1000 Subject: [PSUBS-MAILIST] second stage adjusting In-Reply-To: <012401dc8c55$73d5c310$5b814930$@airesearch.nl> References: <00ec01dc8beb$69c0ca10$3d425e30$@airesearch.nl> <012401dc8c55$73d5c310$5b814930$@airesearch.nl> Message-ID: ?? On Fri, Jan 23, 2026 at 1:08?AM via Personal_Submersibles < personal_submersibles at psubs.org> wrote: > Hi Rick, > > > > I meant that this is probably know to you. Proverbs translate not very > well ? > > > > Br, Emile > > > > *Van:* Personal_Submersibles *Namens > *Rick Patton via Personal_Submersibles > *Verzonden:* vrijdag 23 januari 2026 05:35 > *Aan:* Personal Submersibles General Discussion < > personal_submersibles at psubs.org> > *Onderwerp:* Re: [PSUBS-MAILIST] second stage adjusting > > > > Hi Emile, not sure what you mean by open door? My second stage is probably > 18" to 24" lower than the thrusters but someone in the group said that he > had adjusted his second stage I thought to more over bottom pressure than > how they come off the shelf. > > > > Rick > > > > On Thu, Jan 22, 2026 at 12:07?PM via Personal_Submersibles < > personal_submersibles at psubs.org> wrote: > > Hi Rick, > > > > Maybe a open door but the (vertical) position makes also a difference. > Some 10-20?lower than the thruster will create overpressure. > > However, it should be tight without overpressure. > > > > Br, Emile > > > > *Van:* Personal_Submersibles *Namens > *Rick Patton via Personal_Submersibles > *Verzonden:* donderdag 22 januari 2026 22:32 > *Aan:* psubs chat room > *Onderwerp:* [PSUBS-MAILIST] second stage adjusting > > > > I had shared about a thruster leaking on my first dip. Someone in the > group said that they had adjusted their second stage for more positive > pressure. I am not sure how to do that. > > > > Rick > > _______________________________________________ > Personal_Submersibles mailing list > Personal_Submersibles at psubs.org > http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles > > _______________________________________________ > Personal_Submersibles mailing list > Personal_Submersibles at psubs.org > http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles > -------------- next part -------------- An HTML attachment was scrubbed... URL: From personal_submersibles at psubs.org Fri Jan 23 14:03:47 2026 From: personal_submersibles at psubs.org (Rick Patton via Personal_Submersibles) Date: Fri, 23 Jan 2026 09:03:47 -1000 Subject: [PSUBS-MAILIST] second stage adjusting In-Reply-To: <1300040415.1256452.1769186885100@mail.yahoo.com> References: <00ec01dc8beb$69c0ca10$3d425e30$@airesearch.nl> <012401dc8c55$73d5c310$5b814930$@airesearch.nl> <668159612.1443225.1769174596049@mail.yahoo.com> <1300040415.1256452.1769186885100@mail.yahoo.com> Message-ID: The air as it expands comes out the two stage regulator that is mounted low. On Fri, Jan 23, 2026 at 7:08?AM Jon Wallace via Personal_Submersibles < personal_submersibles at psubs.org> wrote: > How do you release pressure from the motors when surfacing? > > > On Friday, January 23, 2026 at 08:25:20 AM EST, hank pronk via > Personal_Submersibles wrote: > > Hi Rick, I use a first stage regulator with the spring removed to act as > the pressure compensator. I use a first stage to bring down the pressure > from the tank as normal, then send that air to the second first stage > regulatow with spring removed, then to the motors. The output pressure to > the motor is a constant 2 psi or so. I tie all the motors and arm to the > one regulator. I have had no luck with the scuba second stage regulator > set up. Tested to 400 feet, no issues. > Hank > > > _______________________________________________ > Personal_Submersibles mailing list > Personal_Submersibles at psubs.org > http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles > -------------- next part -------------- An HTML attachment was scrubbed... URL: From personal_submersibles at psubs.org Fri Jan 23 14:13:27 2026 From: personal_submersibles at psubs.org (Rick Patton via Personal_Submersibles) Date: Fri, 23 Jan 2026 09:13:27 -1000 Subject: [PSUBS-MAILIST] second stage adjusting In-Reply-To: <61197843.1533855.1769190018906@mail.yahoo.com> References: <61197843.1533855.1769190018906@mail.yahoo.com> Message-ID: Hey Alan, I run all thrusters and the arm from the second stage port on the inhale exhale port. I don't have an over-pressure valve in the system. Is that a backup for if the second stage does not vent properly? Rick. On Fri, Jan 23, 2026 at 8:07?AM Alan James via Personal_Submersibles < personal_submersibles at psubs.org> wrote: > Rick, > I resin printed a second stage regulator body > with an adjustment bolt & spring to give up to 10psi overpressure. It has > a diagphram rated for 80psi that was built for me in China & a standard 2nd > stage mechanism for regulating air. > It has an outlet fitting to an 8 port manifold. > On the manifold I have an over- pressure valve for pressure relief in the > system. > I am building an electric manipulator & using the compensator for that as > well as the thrusters. > Hanks method of using an additional 1st stage should work. I believe Karl > Stanley is or was using this method. He said he let the over- pressure > bubble out through the thruster o-rings. > Not sure what type of 1st stage Hank is using. > Possibly the more sensitive diaphragm type. > You could run a line from the first stage to a manifold and put a beer > brewing type over- pressure valve in the manifold. Not sure how long the > spring in the manifold will last though. I think they are 304 stainless. > Cheers. > > > Yahoo Mail: Search, organise, conquer > > > _______________________________________________ > Personal_Submersibles mailing list > Personal_Submersibles at psubs.org > http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles > -------------- next part -------------- An HTML attachment was scrubbed... URL: From personal_submersibles at psubs.org Fri Jan 23 14:35:36 2026 From: personal_submersibles at psubs.org (Alan James via Personal_Submersibles) Date: Fri, 23 Jan 2026 19:35:36 +0000 (UTC) Subject: [PSUBS-MAILIST] second stage adjusting In-Reply-To: References: <61197843.1533855.1769190018906@mail.yahoo.com> Message-ID: <837722923.1575867.1769196936111@mail.yahoo.com> Rick,on my system there isn't an exhaust valve like a normal regulator.When I did use a normal second stage regulator I fitted 2 short PVC tubes into the exhaust outlet by heating it & forcing the tube in to it. This helped stop water getting in the system.?I did a video of my over- pressure regulator & posted it on the Psubs Facebook page.If you went on there & searched my name you would come across it.Alan Yahoo Mail: Search, organise, conquer On Sat, 24 Jan 2026 at 8:15 am, Rick Patton via Personal_Submersibles wrote: _______________________________________________ Personal_Submersibles mailing list Personal_Submersibles at psubs.org http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles -------------- next part -------------- An HTML attachment was scrubbed... URL: From personal_submersibles at psubs.org Fri Jan 23 14:48:33 2026 From: personal_submersibles at psubs.org (Jon Wallace via Personal_Submersibles) Date: Fri, 23 Jan 2026 19:48:33 +0000 (UTC) Subject: [PSUBS-MAILIST] second stage adjusting In-Reply-To: References: <00ec01dc8beb$69c0ca10$3d425e30$@airesearch.nl> <012401dc8c55$73d5c310$5b814930$@airesearch.nl> <668159612.1443225.1769174596049@mail.yahoo.com> <1300040415.1256452.1769186885100@mail.yahoo.com> Message-ID: <785269687.1521331.1769197713197@mail.yahoo.com> Hi Rick, the second stage setup I understand.? My question was directed to Hank regarding his system of using sequential 1st stages since there's no escape for the pressurized air in the motor the same way there is when using a second stage.? I've seen Stanley describe just letting that air blow out through the thruster o-rings but seems like that would come with some risk with the Minn-Kota motors. Jon? On Friday, January 23, 2026 at 02:05:39 PM EST, Rick Patton via Personal_Submersibles wrote: The air as it expands comes out the two stage regulator?that is mounted low. On Fri, Jan 23, 2026 at 7:08?AM Jon Wallace via Personal_Submersibles wrote: > How do you release pressure from the motors when surfacing? > > > On Friday, January 23, 2026 at 08:25:20 AM EST, hank pronk via Personal_Submersibles wrote: > > Hi Rick, I use a first stage regulator with the spring removed to act as the pressure compensator.? I use a first stage to bring down the pressure from the tank as normal, then send that air to the second first stage regulatow with spring removed, then to the motors.? The output pressure to the motor is a constant 2 psi or so.? I tie all the motors and arm to the one regulator.? I have had no luck with the scuba second stage regulator set up.? Tested to 400 feet, no issues. > Hank > > From personal_submersibles at psubs.org Fri Jan 23 15:01:36 2026 From: personal_submersibles at psubs.org (Sean T. Stevenson via Personal_Submersibles) Date: Fri, 23 Jan 2026 20:01:36 +0000 Subject: [PSUBS-MAILIST] second stage adjusting In-Reply-To: <785269687.1521331.1769197713197@mail.yahoo.com> References: <00ec01dc8beb$69c0ca10$3d425e30$@airesearch.nl> <012401dc8c55$73d5c310$5b814930$@airesearch.nl> <668159612.1443225.1769174596049@mail.yahoo.com> <1300040415.1256452.1769186885100@mail.yahoo.com> <785269687.1521331.1769197713197@mail.yahoo.com> Message-ID: Any industrial pressure reducing regulator with pressure tracking bias and "self-relieving" or "self-venting" functionality should serve this purpose. Look at the Tescom 44-4000 series as an example. Sean -------- Original Message -------- On Friday, 01/23/26 at 11:49 Jon Wallace via Personal_Submersibles wrote: Hi Rick, the second stage setup I understand.? My question was directed to Hank regarding his system of using sequential 1st stages since there's no escape for the pressurized air in the motor the same way there is when using a second stage.? I've seen Stanley describe just letting that air blow out through the thruster o-rings but seems like that would come with some risk with the Minn-Kota motors. Jon On Friday, January 23, 2026 at 02:05:39 PM EST, Rick Patton via Personal_Submersibles wrote: The air as it expands comes out the two stage regulator?that is mounted low. On Fri, Jan 23, 2026 at 7:08?AM Jon Wallace via Personal_Submersibles wrote: > How do you release pressure from the motors when surfacing? > > > On Friday, January 23, 2026 at 08:25:20 AM EST, hank pronk via Personal_Submersibles wrote: > > Hi Rick, I use a first stage regulator with the spring removed to act as the pressure compensator.? I use a first stage to bring down the pressure from the tank as normal, then send that air to the second first stage regulatow with spring removed, then to the motors.? The output pressure to the motor is a constant 2 psi or so.? I tie all the motors and arm to the one regulator.? I have had no luck with the scuba second stage regulator set up.? Tested to 400 feet, no issues. > Hank > > _______________________________________________ Personal_Submersibles mailing list Personal_Submersibles at psubs.org http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles From personal_submersibles at psubs.org Fri Jan 23 16:23:42 2026 From: personal_submersibles at psubs.org (Jon Wallace via Personal_Submersibles) Date: Fri, 23 Jan 2026 21:23:42 +0000 (UTC) Subject: [PSUBS-MAILIST] second stage adjusting In-Reply-To: References: <00ec01dc8beb$69c0ca10$3d425e30$@airesearch.nl> <012401dc8c55$73d5c310$5b814930$@airesearch.nl> <668159612.1443225.1769174596049@mail.yahoo.com> <1300040415.1256452.1769186885100@mail.yahoo.com> <785269687.1521331.1769197713197@mail.yahoo.com> Message-ID: <551699078.3695803.1769203422067@mail.yahoo.com> Seems to be a large variation in pricing on the Tescom. Branom Instrument wants $5299.00 AliExpress wants $798.00 Alibaba has one for $300.00 Jon On Friday, January 23, 2026 at 03:03:24 PM EST, Sean T. Stevenson via Personal_Submersibles wrote: Any industrial pressure reducing regulator with pressure tracking bias and? "self-relieving" or "self-venting" functionality should serve this purpose. Look at the Tescom 44-4000 series as an example. Sean From personal_submersibles at psubs.org Fri Jan 23 16:43:29 2026 From: personal_submersibles at psubs.org (Alan James via Personal_Submersibles) Date: Fri, 23 Jan 2026 21:43:29 +0000 (UTC) Subject: [PSUBS-MAILIST] second stage adjusting In-Reply-To: References: <00ec01dc8beb$69c0ca10$3d425e30$@airesearch.nl> <012401dc8c55$73d5c310$5b814930$@airesearch.nl> <668159612.1443225.1769174596049@mail.yahoo.com> <1300040415.1256452.1769186885100@mail.yahoo.com> <785269687.1521331.1769197713197@mail.yahoo.com> Message-ID: <1925477432.3704908.1769204609416@mail.yahoo.com> Psubs people like Hugh Fulton, Cliff Redus,? Brian Hughes & myself did a lot of experimentation in using venting pressure regulators. Cliff found the venting hole too small & it caused a pressure build up in his system.?I found it difficult to find a replacement non corrosive spring for the relieving system.It had to be mounted upside down to help prevent water ingress & the 316 regulators were relatively inexpensive.As the 1st stage regulator can feed in to a manifold a beer brewing over pressure regulator can screw in to the manifold & solve the problem.Alan Yahoo Mail: Search, organise, conquer On Sat, 24 Jan 2026 at 9:03 am, Sean T. Stevenson via Personal_Submersibles wrote: Any industrial pressure reducing regulator with pressure tracking bias and? "self-relieving" or "self-venting" functionality should serve this purpose. Look at the Tescom 44-4000 series as an example. Sean -------- Original Message -------- On Friday, 01/23/26 at 11:49 Jon Wallace via Personal_Submersibles wrote: Hi Rick, the second stage setup I understand.? My question was directed to Hank regarding his system of using sequential 1st stages since there's no escape for the pressurized air in the motor the same way there is when using a second stage.? I've seen Stanley describe just letting that air blow out through the thruster o-rings but seems like that would come with some risk with the Minn-Kota motors. Jon On Friday, January 23, 2026 at 02:05:39 PM EST, Rick Patton via Personal_Submersibles wrote: The air as it expands comes out the two stage regulator?that is mounted low. On Fri, Jan 23, 2026 at 7:08?AM Jon Wallace via Personal_Submersibles wrote: > How do you release pressure from the motors when surfacing? > > > On Friday, January 23, 2026 at 08:25:20 AM EST, hank pronk via Personal_Submersibles wrote: > > Hi Rick, I use a first stage regulator with the spring removed to act as the pressure compensator.? I use a first stage to bring down the pressure from the tank as normal, then send that air to the second first stage regulatow with spring removed, then to the motors.? The output pressure to the motor is a constant 2 psi or so.? I tie all the motors and arm to the one regulator.? I have had no luck with the scuba second stage regulator set up.? Tested to 400 feet, no issues. > Hank > > _______________________________________________ Personal_Submersibles mailing list Personal_Submersibles at psubs.org http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles _______________________________________________ Personal_Submersibles mailing list Personal_Submersibles at psubs.org http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles -------------- next part -------------- An HTML attachment was scrubbed... URL: From personal_submersibles at psubs.org Fri Jan 23 17:54:12 2026 From: personal_submersibles at psubs.org (hank pronk via Personal_Submersibles) Date: Fri, 23 Jan 2026 15:54:12 -0700 Subject: [PSUBS-MAILIST] second stage adjusting In-Reply-To: References: Message-ID: An HTML attachment was scrubbed... URL: From personal_submersibles at psubs.org Fri Jan 23 20:18:57 2026 From: personal_submersibles at psubs.org (Rick Patton via Personal_Submersibles) Date: Fri, 23 Jan 2026 15:18:57 -1000 Subject: [PSUBS-MAILIST] second stage adjusting In-Reply-To: References: Message-ID: Hi Hank, could you send me a picture of it so I can see the size and how I would plumb it to the existing system?Thanks. Rick On Fri, Jan 23, 2026 at 1:38?PM hank pronk via Personal_Submersibles < personal_submersibles at psubs.org> wrote: > Rick, sorry forgot to mention, I have a small adjustable relief valve > tee?d into the pressure line. > Hank > Sent from my iPhone > > On Jan 23, 2026, at 12:03?PM, Rick Patton via Personal_Submersibles < > personal_submersibles at psubs.org> wrote: > > ? > ?? > > On Fri, Jan 23, 2026 at 1:08?AM via Personal_Submersibles < > personal_submersibles at psubs.org> wrote: > >> Hi Rick, >> >> >> >> I meant that this is probably know to you. Proverbs translate not very >> well ? >> >> >> >> Br, Emile >> >> >> >> *Van:* Personal_Submersibles *Namens >> *Rick Patton via Personal_Submersibles >> *Verzonden:* vrijdag 23 januari 2026 05:35 >> *Aan:* Personal Submersibles General Discussion < >> personal_submersibles at psubs.org> >> *Onderwerp:* Re: [PSUBS-MAILIST] second stage adjusting >> >> >> >> Hi Emile, not sure what you mean by open door? My second stage is >> probably 18" to 24" lower than the thrusters but someone in the group said >> that he had adjusted his second stage I thought to more over bottom >> pressure than how they come off the shelf. >> >> >> >> Rick >> >> >> >> On Thu, Jan 22, 2026 at 12:07?PM via Personal_Submersibles < >> personal_submersibles at psubs.org> wrote: >> >> Hi Rick, >> >> >> >> Maybe a open door but the (vertical) position makes also a difference. >> Some 10-20?lower than the thruster will create overpressure. >> >> However, it should be tight without overpressure. >> >> >> >> Br, Emile >> >> >> >> *Van:* Personal_Submersibles *Namens >> *Rick Patton via Personal_Submersibles >> *Verzonden:* donderdag 22 januari 2026 22:32 >> *Aan:* psubs chat room >> *Onderwerp:* [PSUBS-MAILIST] second stage adjusting >> >> >> >> I had shared about a thruster leaking on my first dip. Someone in the >> group said that they had adjusted their second stage for more positive >> pressure. I am not sure how to do that. >> >> >> >> Rick >> >> _______________________________________________ >> Personal_Submersibles mailing list >> Personal_Submersibles at psubs.org >> http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles >> >> _______________________________________________ >> Personal_Submersibles mailing list >> Personal_Submersibles at psubs.org >> http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles >> > _______________________________________________ > Personal_Submersibles mailing list > Personal_Submersibles at psubs.org > http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles > > _______________________________________________ > Personal_Submersibles mailing list > Personal_Submersibles at psubs.org > http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles > -------------- next part -------------- An HTML attachment was scrubbed... URL: From personal_submersibles at psubs.org Sun Jan 25 21:13:23 2026 From: personal_submersibles at psubs.org (Greg via Personal_Submersibles) Date: Sun, 25 Jan 2026 21:13:23 -0500 Subject: [PSUBS-MAILIST] USCG update In-Reply-To: <6972EF9300000974@altprdrgo001.altice.prod.cloud.openwave.ai> References: <6972EF9300000974@altprdrgo001.altice.prod.cloud.openwave.ai> Message-ID: Thanks for the info! No bears were poked in the creation of this email! (Good advice?) Best personal regards, Greg > > On Jan 22, 2026 at 10:51 PM, wrote: > > > > I suggest that you don't poke the bear. > > > > John K. > > (203) 414-1000 > > > > > > > > > Sent via the Samsung Galaxy S10e, an AT&T 5G Evolution capable smartphone > > > > > > > > -------- Original message -------- > > From: Jon Wallace via Personal_Submersibles > > Date: 1/22/26 10:30 PM (GMT-05:00) > > To: Personal Submersibles General Discussion > > Subject: [PSUBS-MAILIST] USCG update > > > Gentlemen, > > The USCG has declined our invitation to attend the 2026 convention citing a restriction on attending conferences. See the following quoted text which is the entirety of their response: > > "Thank you for the invitation, however unfortunately we are no longer permitted > to attend conferences. As we previously discussed we are not looking to add > additional regulations to recreational submersibles at this time. If that > ever changes, we will make sure we reach out to PSubs for their involvement." > > While I am disappointed the USCG will not be attending, this email and discussions I have had with USCG personnel in Washington HQ, do seem to suggest that there are no impending regulations that will impact us, or our organization, in the foreseeable future. While that is great news it is even more incumbent upon us to ensure we continue to design, fabricate, and operate safely, and adhere to industry standards as set by ABS, ASME, and ourselves. In this way, we will continue to maintain our reputation and preserve our rights to enjoy our hobby with minimal government interference. > > In the meantime, I feel this was a missed opportunity by the USCG that risks reinforcing the perception that the private submersible community?s expertise and concerns are not being given due consideration. For that reason, I am drafting a letter to the USCG Commandant respectfully expressing our disappointment and planting a seed for reconsideration in the future. > > Jon > > _______________________________________________ > Personal_Submersibles mailing list > Personal_Submersibles at psubs.org > http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles > _______________________________________________ Personal_Submersibles mailing list Personal_Submersibles at psubs.org http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles -------------- next part -------------- An HTML attachment was scrubbed... URL: From personal_submersibles at psubs.org Mon Jan 26 13:49:21 2026 From: personal_submersibles at psubs.org (hank pronk via Personal_Submersibles) Date: Mon, 26 Jan 2026 11:49:21 -0700 Subject: [PSUBS-MAILIST] second stage adjusting In-Reply-To: References: Message-ID: An HTML attachment was scrubbed... URL: -------------- next part -------------- A non-text attachment was scrubbed... Name: image0.jpeg Type: image/jpeg Size: 164292 bytes Desc: not available URL: From personal_submersibles at psubs.org Mon Jan 26 13:50:34 2026 From: personal_submersibles at psubs.org (hank pronk via Personal_Submersibles) Date: Mon, 26 Jan 2026 11:50:34 -0700 Subject: [PSUBS-MAILIST] second stage adjusting In-Reply-To: References: Message-ID: An HTML attachment was scrubbed... URL: From personal_submersibles at psubs.org Mon Jan 26 16:21:18 2026 From: personal_submersibles at psubs.org (Rick Patton via Personal_Submersibles) Date: Mon, 26 Jan 2026 11:21:18 -1000 Subject: [PSUBS-MAILIST] second stage adjusting In-Reply-To: References: Message-ID: Hi Hank, I got a picture of the two place sub but I thought that you might have a picture of just the overpressure part up close so I could see it? You going to make it to the convention coming up? Rick On Mon, Jan 26, 2026 at 8:51?AM hank pronk via Personal_Submersibles < personal_submersibles at psubs.org> wrote: > Rick, I sent a pic but if it doesn?t make it, email me and I will send it > direct to you > Hank > Sent from my iPhone > > On Jan 23, 2026, at 6:19?PM, Rick Patton via Personal_Submersibles < > personal_submersibles at psubs.org> wrote: > > ? > Hi Hank, could you send me a picture of it so I can see the size and how I > would plumb it to the existing system?Thanks. > > Rick > > > On Fri, Jan 23, 2026 at 1:38?PM hank pronk via Personal_Submersibles < > personal_submersibles at psubs.org> wrote: > >> Rick, sorry forgot to mention, I have a small adjustable relief valve >> tee?d into the pressure line. >> Hank >> Sent from my iPhone >> >> On Jan 23, 2026, at 12:03?PM, Rick Patton via Personal_Submersibles < >> personal_submersibles at psubs.org> wrote: >> >> ? >> ?? >> >> On Fri, Jan 23, 2026 at 1:08?AM via Personal_Submersibles < >> personal_submersibles at psubs.org> wrote: >> >>> Hi Rick, >>> >>> >>> >>> I meant that this is probably know to you. Proverbs translate not very >>> well ? >>> >>> >>> >>> Br, Emile >>> >>> >>> >>> *Van:* Personal_Submersibles *Namens >>> *Rick Patton via Personal_Submersibles >>> *Verzonden:* vrijdag 23 januari 2026 05:35 >>> *Aan:* Personal Submersibles General Discussion < >>> personal_submersibles at psubs.org> >>> *Onderwerp:* Re: [PSUBS-MAILIST] second stage adjusting >>> >>> >>> >>> Hi Emile, not sure what you mean by open door? My second stage is >>> probably 18" to 24" lower than the thrusters but someone in the group said >>> that he had adjusted his second stage I thought to more over bottom >>> pressure than how they come off the shelf. >>> >>> >>> >>> Rick >>> >>> >>> >>> On Thu, Jan 22, 2026 at 12:07?PM via Personal_Submersibles < >>> personal_submersibles at psubs.org> wrote: >>> >>> Hi Rick, >>> >>> >>> >>> Maybe a open door but the (vertical) position makes also a difference. >>> Some 10-20?lower than the thruster will create overpressure. >>> >>> However, it should be tight without overpressure. >>> >>> >>> >>> Br, Emile >>> >>> >>> >>> *Van:* Personal_Submersibles *Namens >>> *Rick Patton via Personal_Submersibles >>> *Verzonden:* donderdag 22 januari 2026 22:32 >>> *Aan:* psubs chat room >>> *Onderwerp:* [PSUBS-MAILIST] second stage adjusting >>> >>> >>> >>> I had shared about a thruster leaking on my first dip. Someone in the >>> group said that they had adjusted their second stage for more positive >>> pressure. I am not sure how to do that. >>> >>> >>> >>> Rick >>> >>> _______________________________________________ >>> Personal_Submersibles mailing list >>> Personal_Submersibles at psubs.org >>> http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles >>> >>> _______________________________________________ >>> Personal_Submersibles mailing list >>> Personal_Submersibles at psubs.org >>> http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles >>> >> _______________________________________________ >> Personal_Submersibles mailing list >> Personal_Submersibles at psubs.org >> http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles >> >> _______________________________________________ >> Personal_Submersibles mailing list >> Personal_Submersibles at psubs.org >> http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles >> > _______________________________________________ > Personal_Submersibles mailing list > Personal_Submersibles at psubs.org > http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles > > _______________________________________________ > Personal_Submersibles mailing list > Personal_Submersibles at psubs.org > http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles > -------------- next part -------------- An HTML attachment was scrubbed... URL: From personal_submersibles at psubs.org Wed Jan 28 15:43:49 2026 From: personal_submersibles at psubs.org (Alec Smyth via Personal_Submersibles) Date: Wed, 28 Jan 2026 15:43:49 -0500 Subject: [PSUBS-MAILIST] O-rings and cold temperature Message-ID: Here's one for the PSUBS brain trust. I was reading today about the Challenger accident 40 years ago. The O-ring that failed was Viton, and the failure was caused by cold weather in the days prior to the mission. The low was 18F. Per the engineers interviewed for the article, when an O-ring contracts due to extreme cold it sets at its newly reduced size, without regaining its prior shape and elasticity as temperatures go back up. Here's my question. The variant of Viton used on Challenger has a service temperature range with a lower end of -20F, way colder than +18F. Why would 18F have damaged it? The O-rings on Shackleton are Buna-N, which is rated to -40F, but I'd still like to understand the failure mechanism, since the weather forecast calls for 3F (-16C) in a few days' time, and I'll be diving Shackleton in Florida two weeks from now. Best, Alec -------------- next part -------------- An HTML attachment was scrubbed... URL: From personal_submersibles at psubs.org Wed Jan 28 16:19:19 2026 From: personal_submersibles at psubs.org (Sean T. Stevenson via Personal_Submersibles) Date: Wed, 28 Jan 2026 21:19:19 +0000 Subject: [PSUBS-MAILIST] O-rings and cold temperature In-Reply-To: References: Message-ID: <8tUCoK9WP3VzPtVA-TKy_vGX_I99p7Y80IFZh1deSKYfPiPK6ff3mupO688RU4O86jaEsihyPVPTIKGm3WqhA-0XlvVirj2-Z4PvqiSh59o=@protonmail.com> The problem with the shuttle O-rings was their dynamic performance charactetistics, as opposed to the quasi-static ones. Interestingly, there was no actual functional reason for the SRBs to have the O-ring sealed joints at all. The contract for manufacture of the SRBs was awarded to Morton Thiokol out of state for somewhat suspect reasons, but regardless, this necessitated sectioning the booster in order to accommodate inter-state transport by rail, instead of manufacuring them as a single part in a facility adjacent to the launch complex. So, the SRB sections were designed with those joints, comprising a double radial O-ring seal protected from the propellant exhaust gases by a non-incendiary putty and insulation on the inside. The cold temperature on launch day, in addition to shrinking the O-rings and reducing the static sealing contact pressure as installed, also reduced their resiliency by increasing their stiffness and how readily they could both deform under applied pressure and return to their original shape when that pressure was relaxed. The SRB is not simply a tube filled with solid propellant that burns away from the bottom end. In order to maximize specific impulse, you want to burn as much propellant as possible in as little time as possible, so the SRB actually has a hollow core which is ignited from the top down to set the entire core alight, and furthermore, instead of being a simple cylinder, the shape of that core void is convoluted in order to maximize its surface area for the initial burn. The result is very high exhaust gas pressures achieved very rapidly. Ordinarily, the O-rings would rapidly expand and deform into their service (sealing) shape in the presence of the applied pressure, but in the case of Challenger, this pressure was applied too quickly for the cold and stiffened O-rings to keep up with the deformation rate required to maintain the design sealing force through their transition from initial installation shape to their maximum service pressure sealing shape , resulting in blow-by of the hot exhaust gases which ultimately failed the joint structurally. Sean https://proton.me/mail/home -------- Original Message -------- On Wednesday, 01/28/26 at 12:45 Alec Smyth via Personal_Submersibles wrote: > Here's one for the PSUBS brain trust. > > I was reading today about the Challenger accident 40 years ago. The O-ring that failed was Viton, and the failure was caused by cold weather in the days prior to the mission. The low was 18F. Per the engineers interviewed for the article, when an O-ring contracts due to extreme cold it sets at its newly reduced size, without regaining its prior shape and elasticity as temperatures go back up. > > Here's my question. The variant of Viton used on Challenger has a service temperature range with a lower end of -20F, way colder than +18F. Why would 18F have damaged it? > > The O-rings on Shackleton are Buna-N, which is rated to -40F, but I'd still like to understand the failure mechanism, since the weather forecast calls for 3F (-16C) in a few days' time, and I'll be diving Shackleton in Florida two weeks from now. > > Best, > Alec -------------- next part -------------- An HTML attachment was scrubbed... URL: From personal_submersibles at psubs.org Wed Jan 28 17:02:06 2026 From: personal_submersibles at psubs.org (Jefferson Tortorelli via Personal_Submersibles) Date: Wed, 28 Jan 2026 22:02:06 +0000 Subject: [PSUBS-MAILIST] O-rings and cold temperature In-Reply-To: <8tUCoK9WP3VzPtVA-TKy_vGX_I99p7Y80IFZh1deSKYfPiPK6ff3mupO688RU4O86jaEsihyPVPTIKGm3WqhA-0XlvVirj2-Z4PvqiSh59o=@protonmail.com> References: <8tUCoK9WP3VzPtVA-TKy_vGX_I99p7Y80IFZh1deSKYfPiPK6ff3mupO688RU4O86jaEsihyPVPTIKGm3WqhA-0XlvVirj2-Z4PvqiSh59o=@protonmail.com> Message-ID: That was a wonderful and informative description! Thank you. Jefferson Tortorelli Tortorelli Creations 4910 Santa Anita Avenue El Monte, CA 91731 Phone ? 909-908-3795 Website: Tortorelli.com From: Personal_Submersibles On Behalf Of Sean T. Stevenson via Personal_Submersibles Sent: Wednesday, January 28, 2026 1:19 PM To: Personal Submersibles General Discussion Subject: Re: [PSUBS-MAILIST] O-rings and cold temperature The problem with the shuttle O-rings was their dynamic performance charactetistics, as opposed to the quasi-static ones. Interestingly, there was no actual functional reason for the SRBs to have the O-ring sealed joints at all. The contract for manufacture of the SRBs was awarded to Morton Thiokol out of state for somewhat suspect reasons, but regardless, this necessitated sectioning the booster in order to accommodate inter-state transport by rail, instead of manufacuring them as a single part in a facility adjacent to the launch complex. So, the SRB sections were designed with those joints, comprising a double radial O-ring seal protected from the propellant exhaust gases by a non-incendiary putty and insulation on the inside. The cold temperature on launch day, in addition to shrinking the O-rings and reducing the static sealing contact pressure as installed, also reduced their resiliency by increasing their stiffness and how readily they could both deform under applied pressure and return to their original shape when that pressure was relaxed. The SRB is not simply a tube filled with solid propellant that burns away from the bottom end. In order to maximize specific impulse, you want to burn as much propellant as possible in as little time as possible, so the SRB actually has a hollow core which is ignited from the top down to set the entire core alight, and furthermore, instead of being a simple cylinder, the shape of that core void is convoluted in order to maximize its surface area for the initial burn. The result is very high exhaust gas pressures achieved very rapidly. Ordinarily, the O-rings would rapidly expand and deform into their service (sealing) shape in the presence of the applied pressure, but in the case of Challenger, this pressure was applied too quickly for the cold and stiffened O-rings to keep up with the deformation rate required to maintain the design sealing force through their transition from initial installation shape to their maximum service pressure sealing shape , resulting in blow-by of the hot exhaust gases which ultimately failed the joint structurally. Sean -------- Original Message -------- On Wednesday, 01/28/26 at 12:45 Alec Smyth via Personal_Submersibles > wrote: Here's one for the PSUBS brain trust. I was reading today about the Challenger accident 40 years ago. The O-ring that failed was Viton, and the failure was caused by cold weather in the days prior to the mission. The low was 18F. Per the engineers interviewed for the article, when an O-ring contracts due to extreme cold it sets at its newly reduced size, without regaining its prior shape and elasticity as temperatures go back up. Here's my question. The variant of Viton used on Challenger has a service temperature range with a lower end of -20F, way colder than +18F. Why would 18F have damaged it? The O-rings on Shackleton are Buna-N, which is rated to -40F, but I'd still like to understand the failure mechanism, since the weather forecast calls for 3F (-16C) in a few days' time, and I'll be diving Shackleton in Florida two weeks from now. Best, Alec -------------- next part -------------- An HTML attachment was scrubbed... URL: From personal_submersibles at psubs.org Wed Jan 28 19:23:21 2026 From: personal_submersibles at psubs.org (hank pronk via Personal_Submersibles) Date: Wed, 28 Jan 2026 17:23:21 -0700 Subject: [PSUBS-MAILIST] second stage adjusting In-Reply-To: References: Message-ID: An HTML attachment was scrubbed... URL: From personal_submersibles at psubs.org Wed Jan 28 19:41:25 2026 From: personal_submersibles at psubs.org (Alec Smyth via Personal_Submersibles) Date: Wed, 28 Jan 2026 19:41:25 -0500 Subject: [PSUBS-MAILIST] O-rings and cold temperature In-Reply-To: <8tUCoK9WP3VzPtVA-TKy_vGX_I99p7Y80IFZh1deSKYfPiPK6ff3mupO688RU4O86jaEsihyPVPTIKGm3WqhA-0XlvVirj2-Z4PvqiSh59o=@protonmail.com> References: <8tUCoK9WP3VzPtVA-TKy_vGX_I99p7Y80IFZh1deSKYfPiPK6ff3mupO688RU4O86jaEsihyPVPTIKGm3WqhA-0XlvVirj2-Z4PvqiSh59o=@protonmail.com> Message-ID: Thanks Sean! That's a bit different reasoning than the one given in the article (that is wasn't the cold on launch day that did it, so much as a permanent set taken on days prior when it was colder.) I do think that, fortunately for us, there's something fundamental that makes O-ring seals problems more forgiving on subs than on spacecraft. Its the fact that if an O-ring is going to seal poorly it tends to happen at low pressure, which for subs means on the surface. But spacecraft start with "high" pressure that tapers off as they climb. I'm guessing that's why Challenger blew up a little over a minute into her flight. On Wed, Jan 28, 2026 at 4:20?PM Sean T. Stevenson via Personal_Submersibles wrote: > The problem with the shuttle O-rings was their dynamic performance > charactetistics, as opposed to the quasi-static ones. > > Interestingly, there was no actual functional reason for the SRBs to have > the O-ring sealed joints at all. The contract for manufacture of the SRBs > was awarded to Morton Thiokol out of state for somewhat suspect reasons, > but regardless, this necessitated sectioning the booster in order to > accommodate inter-state transport by rail, instead of manufacuring them as > a single part in a facility adjacent to the launch complex. > > So, the SRB sections were designed with those joints, comprising a double > radial O-ring seal protected from the propellant exhaust gases by a > non-incendiary putty and insulation on the inside. The cold temperature on > launch day, in addition to shrinking the O-rings and reducing the static > sealing contact pressure as installed, also reduced their resiliency by > increasing their stiffness and how readily they could both deform under > applied pressure and return to their original shape when that pressure was > relaxed. > > The SRB is not simply a tube filled with solid propellant that burns away > from the bottom end. In order to maximize specific impulse, you want to > burn as much propellant as possible in as little time as possible, so the > SRB actually has a hollow core which is ignited from the top down to set > the entire core alight, and furthermore, instead of being a simple > cylinder, the shape of that core void is convoluted in order to > maximize its surface area for the initial burn. The result is very high > exhaust gas pressures achieved very rapidly. Ordinarily, the O-rings would > rapidly expand and deform into their service (sealing) shape in the > presence of the applied pressure, but in the case of Challenger, > this pressure was applied too quickly for the cold and stiffened O-rings to > keep up with the deformation rate required to maintain the design sealing > force through their transition from initial installation shape to their > maximum service pressure sealing shape , resulting in blow-by of the > hot exhaust gases which ultimately failed the joint structurally. > > Sean > > > > > > -------- Original Message -------- > On Wednesday, 01/28/26 at 12:45 Alec Smyth via Personal_Submersibles < > personal_submersibles at psubs.org> wrote: > > Here's one for the PSUBS brain trust. > > I was reading today about the Challenger accident 40 years ago. The O-ring > that failed was Viton, and the failure was caused by cold weather in the > days prior to the mission. The low was 18F. Per the engineers interviewed > for the article, when an O-ring contracts due to extreme cold it sets at > its newly reduced size, without regaining its prior shape and elasticity as > temperatures go back up. > > Here's my question. The variant of Viton used on Challenger has a service > temperature range with a lower end of -20F, way colder than +18F. Why would > 18F have damaged it? > > The O-rings on Shackleton are Buna-N, which is rated to -40F, but I'd > still like to understand the failure mechanism, since the weather forecast > calls for 3F (-16C) in a few days' time, and I'll be diving Shackleton in > Florida two weeks from now. > > Best, > Alec > > _______________________________________________ > Personal_Submersibles mailing list > Personal_Submersibles at psubs.org > http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles > -------------- next part -------------- An HTML attachment was scrubbed... URL: From personal_submersibles at psubs.org Wed Jan 28 20:15:48 2026 From: personal_submersibles at psubs.org (Sean T. Stevenson via Personal_Submersibles) Date: Thu, 29 Jan 2026 01:15:48 +0000 Subject: [PSUBS-MAILIST] O-rings and cold temperature In-Reply-To: References: <8tUCoK9WP3VzPtVA-TKy_vGX_I99p7Y80IFZh1deSKYfPiPK6ff3mupO688RU4O86jaEsihyPVPTIKGm3WqhA-0XlvVirj2-Z4PvqiSh59o=@protonmail.com> Message-ID: I could be missing some information. Obviously NASA and MT engineers would be the authoritative word on the issue, but to me, it actually makes sense that a temperature swing in the positive direction would be more likely to induce compression set. Here's why: Viton is generally pretty resistant to compression set, but in any seal design, you have a target initial installation "squeeze", or compression of the O-ring, which should be enough to maintain an effective seal in the absence of differential pressure. If you want to maximize that initial seal force, you increase the initial squeeze to some value below the value that would cause compression set in your elastomer, so that it will recover fully if you remove the O-ring from the groove. Now, when you increase the system temperature, the groove bore and plug diameters of the metal parts increase, so increasing the height of the groove, but the elastomer cross-sectional diameter also increases, and the coefficient of thermal expansion of the elastomer is something like six times that of the steel, so you end up with a larger O-ring being crushed beyond design squeeze in the groove, and if the resultant squeeze is greater than the value at which compression set begins, then when the temperature cools and everything goes back to normal, the O-ring having suffered compression set will exert less sealing force in the groove. Now, how it could work the other way, is that in addition to cross-sectional "squeeze", an O-ring also nominally experiences a circumferential "stretch", which is nominally slight in most seal designs, but of course as temperatures drop, this stretch is lost in favour of increased cross-sectional diameter of the O-ring, which increases squeeze sympathetically with simultaneously shrinking groove dimensions. If the dimensions of the groove are tight (e.g. 90+ % groove fill), this could induce unrecoverable compression set which would result in lower nominal squeeze once the temperature returned to normal. Many variables here. You'd really need to look at the specific groove design and elastomer to analyze the behaviour. https://proton.me/mail/home As far as PSub applications are concerned, submerged temperatures have a pretty consistent and narrow range that is relatively easy to design seals for. If I were trailering a sub through severe cold in advance of a dive, however, I would be inclined to give it time to equilibrate with the water temperature for a while before diving it. This is also prudent for your acrylic windows if they have been allowed to become thoroughly cold. Sean -------- Original Message -------- On Wednesday, 01/28/26 at 16:42 Alec Smyth via Personal_Submersibles wrote: > Thanks Sean! That's a bit different reasoning than the one given in the article (that is wasn't the cold on launch day that did it, so much as a permanent set taken on days prior when it was colder.) > > I do think that, fortunately for us, there's something fundamental that makes O-ring seals problems more forgiving on subs than on spacecraft. Its the fact that if an O-ring is going to seal poorly it tends to happen at low pressure, which for subs means on the surface. But spacecraft start with "high" pressure that tapers off as they climb. I'm guessing that's why Challenger blew up a little over a minute into her flight. > > On Wed, Jan 28, 2026 at 4:20?PM Sean T. Stevenson via Personal_Submersibles wrote: > >> The problem with the shuttle O-rings was their dynamic performance charactetistics, as opposed to the quasi-static ones. >> >> Interestingly, there was no actual functional reason for the SRBs to have the O-ring sealed joints at all. The contract for manufacture of the SRBs was awarded to Morton Thiokol out of state for somewhat suspect reasons, but regardless, this necessitated sectioning the booster in order to accommodate inter-state transport by rail, instead of manufacuring them as a single part in a facility adjacent to the launch complex. >> >> So, the SRB sections were designed with those joints, comprising a double radial O-ring seal protected from the propellant exhaust gases by a non-incendiary putty and insulation on the inside. The cold temperature on launch day, in addition to shrinking the O-rings and reducing the static sealing contact pressure as installed, also reduced their resiliency by increasing their stiffness and how readily they could both deform under applied pressure and return to their original shape when that pressure was relaxed. >> >> The SRB is not simply a tube filled with solid propellant that burns away from the bottom end. In order to maximize specific impulse, you want to burn as much propellant as possible in as little time as possible, so the SRB actually has a hollow core which is ignited from the top down to set the entire core alight, and furthermore, instead of being a simple cylinder, the shape of that core void is convoluted in order to maximize its surface area for the initial burn. The result is very high exhaust gas pressures achieved very rapidly. Ordinarily, the O-rings would rapidly expand and deform into their service (sealing) shape in the presence of the applied pressure, but in the case of Challenger, this pressure was applied too quickly for the cold and stiffened O-rings to keep up with the deformation rate required to maintain the design sealing force through their transition from initial installation shape to their maximum service pressure sealing shape , resulting in blow-by of the hot exhaust gases which ultimately failed the joint structurally. >> >> Sean >> >> https://proton.me/mail/home >> >> -------- Original Message -------- >> On Wednesday, 01/28/26 at 12:45 Alec Smyth via Personal_Submersibles wrote: >> >>> Here's one for the PSUBS brain trust. >>> >>> I was reading today about the Challenger accident 40 years ago. The O-ring that failed was Viton, and the failure was caused by cold weather in the days prior to the mission. The low was 18F. Per the engineers interviewed for the article, when an O-ring contracts due to extreme cold it sets at its newly reduced size, without regaining its prior shape and elasticity as temperatures go back up. >>> >>> Here's my question. The variant of Viton used on Challenger has a service temperature range with a lower end of -20F, way colder than +18F. Why would 18F have damaged it? >>> >>> The O-rings on Shackleton are Buna-N, which is rated to -40F, but I'd still like to understand the failure mechanism, since the weather forecast calls for 3F (-16C) in a few days' time, and I'll be diving Shackleton in Florida two weeks from now. >>> >>> Best, >>> Alec >> >> _______________________________________________ >> Personal_Submersibles mailing list >> Personal_Submersibles at psubs.org >> http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles -------------- next part -------------- An HTML attachment was scrubbed... URL: