If you design a sub so that if all hard and soft ballast tanks are full of water, and the hull is also completely flooded and you have enough syntactic foam on or in the sub that if you release one or more large drop weights and/or battery pods your positively bouyant, I believe it's a serious safety advantage. When I speak of mold, I'm mostly concerned with it in a sub that never completely floods only standard regular use moisture. Moisture from breathing, a small leak in any one of a thousand plumbing connections, rain as you get into or out of a sub, SCUBA diver(s) coming on board, a wave splashing some water into a open hatch, etc can all bring moisture on board.
There is also many ways to sink a sub with out it having any real mechanical or hull failer that wouldn't require the main hull to be reworked. Like having your hatch open and a rogue wave over takes you, or some how a solenoid valve gets opened when you or your passengers are leaving the sub to go on deck, etc. In that event, as you said you'll have to go through the equipment carefully.
If I use urethane foam in a hyperbaric submarine, the foam will compress and break making the insulation have less R value as well as being porous to moisture. If I use bubble foil insulation, as soon as you add hyperbaric pressure your insulation R value goes way down.
I've had many hyperbaric treatments in a regular steel six person chamber that was un-insulated. It could be quite cold or hot depending on the current weather. It would cost a fair bit to heat or cool the room the chamber was in just to change the temperature of the steel making up the chamber. When we would compress the chamber the air is warm and if the steel of the chamber is cold the air is not warm enough to off set that. If the steel is warm, like in summer months, that extra warm air coming in to compress the air is like a dry sauna. When we would bleed off the air pressure the air would get cold and foggy. This is a pic of the six person chamber I worked on and used.
Some porous materials resist mold growth. As for cork I wouldn't know, but someone here would likely know.
Cheers
Brent
From: "Jon Wallace" <jon@psubs.org>
Reply-To: personal_submersibles@psubs.org
To: <personal_submersibles@psubs.org>
Subject: RE: [PSUBS-MAILIST] Insulation Types That Can Be Used Inside a Sub
Date: Sun, 14 Jan 2007 22:20:05 -0500
Without trying to sound flip, I'm thinking that if your sub floods; mold should be the least of your concerns. One, you're gonna bail and the sub is going to be at the bottom unless you've got enough displacement with the insulation to provide positive bouyancy. Second, I'm guessing that if the sub floods, a complete teardown will be required to ensure the integrity of the sub hull and framing members including ripping out the insulation to get down to the metal. Not to mention that any/all electronics/electrical connections will have to be removed and replaced.
You may have a legitimate point regarding compression of material and its effects inside a hyberbaric chamber, but for a working sub I think your concerns about compression ruining the insulation material and/or bouyancy issues involved with flooding aren't worth worrying about. Regarding the type of material, I know some subs of the 40's and 50's used cork insulation on the hull and frame members.
Jon
This is a subject I've been thinking about for some time now for my live aboard sub ideas as well as for smaller craft. Most insulation choices out there are porous to external air. This means that it can get wet and oh so moldy. Also if you ever flood your sub in any way you'll have allot of work to do. Urethane foam may work well for some designs. I've seen some become old and powdery after a few years but that maybe because of a bad mix and/or UV damage. Urethane foam wouldn't work for me because I want my subs to be able to be used as hyperbaric chambers for both general health benefits at 2 atmospheres as well as for divers with the bends. With this in mind I wouldn't expect urethane foam not to stand up to the internal pressure of the sub(s). If you have a dive boat that is also a submarine that can take care of a
divers hyperbaric chamber needs at the dive sight I know it could save lives.
One insulation type with a reasonable R value that is sealed and can compress under hyperbaric pressure, is a foil covered expensive version of bubble wrap called bubble foil insulation. One brand is call Radiant Guard.
You can find bubble foil insulation at most large hardware stores. One problem though is that because it will compress under pressure it won't help your buoyancy if your sub starts to flood.
This is why I was thinking syntactic foam may be the answer for all my requirements. From what I understand syntactic foam would not compress under pressure. So if your sub floods it will help in your buoyance as well as keeping it's shape and insulation value if internal pressure is raised. In addition to all that if water and air can't get into the syntactic foam then you won't have the mold problems I mentioned or the need to replace insulation if your sub floods. Now since I have not as yet worked with syntactic foam I would love to hear any bodies thoughts on this that have used it as well as others.
The great merit of society is to make one appreciate solitude.
-- Charles Chincholles
Being alone in your submarine can be a wondrous thing.
Brent Hartwig
