/diy/ - Do It Yourself

>mad scientist

lol you agian

>>148949

If I'm unwelcome, I'll leave.

>>148950
I'm not that anon, you're not unwelcome.

>>148940
Remeber just how much pressure there will be per square inch versus the size of your viewing "ports". The bigger the single square area the more it will bend and less stable it will be.

>>148954

>Remeber just how much pressure there will be per square inch versus the size of your viewing "ports". The bigger the single square area the more it will bend and less stable it will be.

Well, considering that the view ports will be on the sides of the container and not the 'roof', the pressure should be zero. This is an ambient pressure diving bell, it does not maintain a pressure differential between interior and exterior. It holds water out by keeping the air inside at the same pressure.

I suspect you know all of that and I simply misunderstood your meaning, though. Is there nonetheless some stress exerted against windows along the 'walls' of the container? If so, why? What principle causes it?

This, or something functionally identical, is what I plan to use to supply air:

http://www.amazon.com/Floating-Surface-Compressor-Hookah-Divers/dp/B000T82PLU

It's very overpriced so I will either look for a better deal on a used one or build my own. The compressor setup for my helmet is battery powered and lasts all of 45 minutes. I could use a generator but that would only be safe if I put it on shore, where there's room to space the generator far away from the compressor so that gas fumes don't get into the air supply (apparently not a problem with hookah rig compressors, don't understand why. Special filters?)

>>148963
I missed the diving bell part.

>>148963

Pressure is roughly equal (minus gradient) across the surface of a submerged object.

>>148968

Yes, precisely. It's just a stationary diving bell with lots of large windows. The primary purpose would be recreation/novelty, although I plan to use one of the two air hoses to feed my diving helmet so that while someone is resting inside the observatory they can watch the other person walking around outside with the helmet. As it is only slightly negatively buoyant when in water, the helmet could simply be hung on a hook outside the observatory when not in use. For everyone else, Spare Air micro scuba cylinders. They offer 57 breaths, which can be stretched out to more than ten minutes with good breath control, plenty of time to explore the area around the observatory and return before your air runs out.

Unlike full sized cylinders, they do not require a trip to the dive shop to refill; They can be refilled up to ten times from a normal sized scuba tank (pic related). With a few of these normal sized tanks affixed to the observatory, it could act as a filling station where people could return to refill their air bottles and rest a while until the refill is complete.

>>148976
>mfw I live 500 miles from the nearest body of water larger than 3 acres.

>>148982

So do I. But back in 1903 my ancestors purchases land on the shore of a large northern lake for mere pennies and built a cabin there. It's where I spend my Summers.

My thinking is, I can deploy the shelter in the lake at 21 feet; The depth where nitrogen saturation does not yet occur, so no decompression is ever needed, but also deep enough that even when the lake ices over in the winter the observatory will remain undisturbed beneath it. When Summer rolls around and the ice melts I can just swim out to the site with the floating compressor, hook the hose up to the observatory, turn the compressor on and presto, all the water that's gotten in over the winter is purged and life support is restored. In fact with a check valve, it should hold air just fine when when the compressor isn't present.

I guess I'll be the idiot to ask, "What about oxygen? That'll eventually run out..."

It would be nice if this underwater home could surface and submerge.

Perhaps a top buoy connected to a leakproof hose down to the place? (but not part of the frame itself)?

>>148998

There's a floating air compressor that sends down more. See: >>148966

>>149012

Too ambitious and expensive. It is a nice fantasy but beyond my financial means to construct. The very best idea is useless to me if it is not within my means to build it. My design for such an observatory is determined entirely by what is cheap and readily available to me.

Once we had this 6' clear plastic ball that screwed together in two pieces. Buoy.
We took it diving with me and 3 other people. (Sea)
There was a charge hole in the side of the ball, which we opened to fill the ball with water and then took it down 600' with us.
These balls are designed to send up things of interest either inside or as the lifting force.
Unbeknownst to me, 2 of the guys wanted to see what it was like floating up inside this ball...so they unscrewed it, one got in and they screwed it back up.
The ball was then affixed to the underwater shackling point to hold it in place when charged, and the outside fella charged the ball with air, and then released the tether sending the ball rocketing upwards.
You can figure out the rest.....that was the last time I ever dived.
...what a mess, and unbelievable stupidity.

>>149028
You might consider installing some way of measuring oxygen content. You might end up subject to asphyxiation, but not the choking/water kind, the kind you can't feel.

>>149088
Also, I'm no diver, but if I understand your story the guy in the ball went rocketing to the surface, then got out and had decompression sickness, thus horrifying you and ending your diving career. Am I right? Did he die, or did he get to a hyperbaric chamber or whatever it is you do to avoid the bends?

600 foot dive? What mixture were you breathing?

>> Going to have diving nightmares now.

>>149102
>Did he die, or did he get to a hyperbaric chamber
I would have expected him to be turned inside out and dead before he even reached the surface.

I think I'd experiment around, but the rubbermaid trashcans sound like they'd be too weak and would collapse inward without some kind of strutting.

The ballast system should be pressure tanks that can be filled with air or water. This way you could float it out there, fill the tanks with water to sink it, and if you chose to move or raise it again, you could do so.

This requires a lot of valves, so try to do it in a uniform way and LABEL them all. If you could make a different size/type of valve for air/water, you probably should.

Air quality sampling and check valves, warning siren if the surface compressor fails. The check valve would prevent collapse, but the air wouldn't be refreshed.

>>149148

Ballast tanks by themselves are not sufficient. Water is not heavier than the surrounding water. They are not used alone to weigh down submersibles; Rather, the subs are loaded with enough lead weight that they only float when the ballast tanks are filled with air; This way, flooding the tanks to different degrees precisely controls how positively or negatively buoyant the sub is, within a specific range.

But with tanks alone, even when full of water, they only weigh as much as the materials that the tanks are made of.

One thing to keep in mind about these underwater, air filled, enclosures is that the air density of the enclosure will be different than that at the surface.

This poses a significant risk if the diver doesn't exhale as they surface. Essentially, if your lungs are "full" on the bottom (supplied by the underwater enclosure), as you rise to the static-pressure on the surface, your lungs will continue to expand beyond their healthy extents. That will destroy your lungs.

... another danger in addition to simply low oxygen.

>>149173

Yup, that's called an air embolism. I took special care to avoid that while testing the homemade diving helmet.

NAUI open water diver here.

I would not trust my life on this.

>>149178

No, an air embolism is when gasses that were under pressure 'bubble out' of the bloodstream and tissues, blocking blood vessels and wreaking all sorts of havoc.

The bends are an exceptionally painful way to die.

>>149088
>There was a charge hole in the side of the ball, which we opened to fill the ball with water and then took it down 600' with us.

>>149185
Takes a little while to happen too.

Worse of all, with a serious case of DCS, there's nothing they can really do about it except watch you die.

>>149187
Also, calculated it out, pressure at 600' is roughly 300 psi.

Enough to crush an average air tank like a beer can. At 350', the pressure exerted on the human body is enough to cause euphoria, drunkenness, poor judgement, and unconsciousness.

>>149197
Oh, and I also forgot to mention, but using pure air below 100' is a lousy idea, as narcosis may occur due to nitrogen and oxygen content. That's where the technical airs come into play... nitrox, heliox, trimix... fun for the whole family.

legorobot will you ever do rapeture with humans or is the sexxual offending thing still bothering you?

I don't know how much this would affect you in a lake, but from my experiences spearfishing those hookah things pretty much scare everything interesting away. If you were wanting an observatory that wouldn't scare everything away your best bet would probably be just to dive down with a couple of tanks and periodically refresh your air supply with those. It would still cause a disturbance but it wouldn't be constant like the hookah would.

That being said, it may be different in a lake. In salt water the sounds pneumatic guns make drive everything away. In fresh water they get lots more use because the freshwater fish either don't care or are attracted by the noise.

Also, are there rocks anywhere about? If your lake is anything like the lakes I've spearfished since moving inland there should be giant boulders strewn about. It might be easier to attach to them with stainless steel chain than to add your own ballast.

Also, now come to think about it, wouldn't it be easier just to use a regular old air compressor and run line to your observatory? Why overspend on a diving hookah which has to run on gas?

You need to be careful of CO2 poisoning, need a way to vent whats in the bubble as you add more air. Just adding more air won't do that much to the CO2 content.