UNDERWATER VIDEO care to predict if the glass container will crush at 70 foot depth ?

[swbca]

@BraceMaker the problem solver . . this might be for you.

I can tell that this 700 pound anchor that I set last summer is not oriented as expected because there is 24" of silty mud at the bottom of this lake. I need to inspect it to see if can be used as is or if needs to be replaced or salvaged and reset. Because of the deep mud I believe the anchor is tipped perhaps 30 degrees towards shore when I loaded the PVC hoop with a winch from shore before it had time to sink deep into the mud. If I have to start over the anchor will have structural outriggers so it will stay level. But there is a chance I can use it as is.

 

Yesterday a used two android phones face to face in a water proof windowed pouch. The touch screens are pressure sensitive so I prevented 30 PSI of direct contact pressure from the pouch window by using the 2 phones screen to screen. Common phone cases kept the screens separated. Had 3 tactical flood flashlights hanging down at 6 feet feet above the camera.

 

Problem: The 30 PSI pressure on the body of phones caused the video recordings to go totally out of focus at depth. the video was sharp down to about 30 feet. The phones are rated as water resistant down to 10' so they internal pressure may not have fully equalized.

 

So this RAOS spaghetti jar is the next possibility. Will it break ? It has a pretty thick wall. An old iPhone 6 fits in the 3.5 x7" jar. I will test this before sending down the phone, but I am 2 hours from the lake and can only guess I have the right stuff to take this video before I get there. I believe the gasketed steel lid will be OK. The water pressure will be 288 pounds pushing the lid against the gasket. It will deflect but will remain functional . . . I hope. (A = π r²) x 30psi

[Jmoski]

My guess is the jar will definitely leak at the seal of the lid well before you get to the desired depth of 70 ft, at 30 ft your already at 2x atmospheric pressure.

[JayShower]

Jars are cheap, you could just do a test and see if it breaks or leaks without the phone. If it leaks, maybe a seal the lid with caulk and then when you want to recover the phone just break the jar?

[swbca]

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[Cnewbert]

Is there a dive club in your area? You could inquire if anyone with an u/w video camera would inspect it for you for a modest amount of money. Most lake areas have police dive teams as well as u/w video cams. Maybe an off-duty officer would do the same.

[Bruce_Butterfield]

Spheres and cylinders are very strong against external pressure. I think the jar will hold up but the weak point will be the lid and/or seal. Easy enough to do a test drop without the phone and see if it leaks.

 

Pulling 700lb out of the mud is challenging but can be done.

[RGilmore]

If you want to be able to move that block, or even just level it where it is, mount a gas-powered trash pump on a floating platform, anchored in place over the weight. Run its 2" hose (typically) down to the weight with a ~ 3-foot x 2" diameter galvanized pipe extension, necked down to 1" diameter at the business end. Using scuba (of course), go down and utilize the high-pressure jet nozzle you just made to blow the silt/mud away from the sides of the block, and THEN out from underneath the block.

 

Be prepared to work by feel, because once you start blowing that muck around you're going to have near-zero visibility. DO NOT WORK UNDERWATER ALONE. Also, FYI, your "700 pound anchor" weighs about 410 pounds under water.

[2Valve]

use a fish camera with display designed for ice fishing. One of our members has one and we needed it last spring to do some inspecting on our course. If I recall, his even has infrared lighting since light diminishes the deeper you go. (If I remember much from my SCUBA days)

[Bruce_Butterfield]

Assuming this is for one end of a slalom course but why does direction matter? Your drawing seems to be for an overly complicated anchor. Wouldn’t a stainless eyebolt in the center be simpler and unidirectional?

[Bulldog]

if the phone is waterproof (cant remember what series started that) fill the jar with water to equalize the pressure.

[swbca]

@Bruce_Butterfield The anchor is for the Bay Lake course which is V.2 of the 1975 course on Christmas Lake. Bay Lake is also deep and requires a course that is only on the surface for our practice sets. Another difference in addition to what is shown below, the horizontal network of pull ropes are all connected 44 feet from the bottom rather than 5 feet from the top to reduce the number of fish lures collected by the course.

 

Your BOS signature is "I'm Ancient, WTH do I know". I did this drawing for the WATER SKIER magazine with a type writer and pencil before the first Apple computer.

[RGilmore]

@swbca - Your tagline says, "Home of the world's first submersible slalom course".

Well, unless your submersible course was built before 1978, it's the "world's second submersible course". As teenagers we built ours in about 35 - 40 ft of water, and used a whole bunch of steel manhole covers (that mysteriously disappeared from the county maintenance yard) for intermediate corner weights. The pull-down lines came from a huge spool of bright yellow 1/4" tri-strand poly rope that somehow went missing at the local power plant. I only mention that because my attorney says the statute of limitations has probably expired - along with any of the adults who were looking for all that stuff at the time.

[swbca]

@RGilmore Fun Story. Ours was built in 1975. Motorized winch with home-made up and down limit switches and a radio control button in the boat added in 1978. Mike Suyderhoud has a 1976 patent for a submersible course. I learned this recently when someone asked me to research this for a Minnesota Lakes history book. Of course I cant' really know if some family did something earlier. I know not much was happening in Europe and Australia at the time.

 

Ours didn't use stolen property but I think I told my wife we needed a new garage door remote control system because our original one had broken. But then she realized I was able to fix it when it showed up in the boat. The range over water was much greater than when it was in the car.

Yours might be the third in the world :)

[RGilmore]

@swbca

B)

[lpskier]

Forgive me if this is absurdly stupid, but if you have a waterproof phone, if you put the phone in the jar, filled the jar with water and then submerged the jar to 70 feet, wouldn’t:

1. The water pressure within the jar stay constant so long as the integrity of the jar and cap remained unchanged;

2. The jar have a greater ability to withstand increased bathymetric pressure because the water inside the jar being a liquid is harder to compress than a gas such as air; and

3. The phone not leak because the pressure in the jar is unchanged?

 

Please excuse any false assumptions and conclusions. I was an English and history major.

[swbca]

@Bulldog @lpskier

I have an iphone6, iphone5s and the original, very first Samsung Galaxy. Those are the models that will fit in the jar. None of them are water proof.

 

But your suggestion is interesting and not easy to answer.

 

Forget about the phone for a minute . . If glass is more compressible (changes size) before it breaks than the compressibility of the water inside jar, then the water in the jar would protect the glass from breaking. If not, it wouldn't.

 

Then back to the phone . . if the glass was compressible to affectively transfer pressure to the internal water, then we would be back to the original problem . . all phone cameras have mechanical focus (hard to believe) (zoom-no, focus-yes) and pressure on the phone, whether by water or air cause the camera's focusing system to put the lens totally out of focus. At least that is what happened with the 2 Samsung phones.

 

About the phones. None of them are waterproof. Recent models water resistant. Water well get in if there is pressure. Recent Samsung models are good down to 10 feet but not for long.

[swbca]

@Bruce_Butterfield Maybe my answer to your question about complexity was incomplete. The stainless loop would work possibly but I wanted a large diameter pipe to act like a pulley to handle 5 ropes being pulled through the hoop with minimal binding and friction. PVC is strong enough if already tipped towards shore where there is 300 pounds of lateral tension on 4" PVC from the winch on shore. In the original course the PVC lasted about 10 years before the AWSA official poly ski rope cut into the PVC. That course was up and down twice a day all summer. Not worried about 10 years any more.

 

The durability concern on this course is the use of stainless steel cable passing though a plastic pipe where the cable is pressed against the lake bottom. The 1975 course was 300 feet from shore and the stretch of poly rope wasn't too bad . . it also passed through pipe for the same reason.

 

The center line of the new course is 710 feet from shore (so no one could complain it was in front of their house) So I needed stainless cable because of the stretch. I bought 250 feet of thick walled tubing (for the ground-contact section) intended for underground natural gas. Don't know how long it will last before the cable cuts into it. If it does it can be replaced easily.

[swbca]

STEP 1 UNMANNED TEST DIVE - SUCCESS

This is before it went down to 69 foot depth and it came back up exactly the same. The cover did not leak because it has 280 pounds of pressure pushing it against its gasket.

STEP 2 Test with iPhone in glass container

The iPhone 6 fit in the glass container but its low light performance was not good enough to see anything. Comparing it to the video from a newer android a few days ago, the android could see with the same lighting arrangement but its mechanical lens focus was pushed to some bad extreme being directly exposed to 30PSI pressure in a water proof flexible windowed pouch. It won't fit in the glass container.

 

The original question about the glass container is answered, but no success with the video . . yet