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Underwater cache idea


RenMin
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Thinking about an underwater cache. A container that would sit on a sunken island in a lake. Maybe four feet deep. An idea I saw involves concrete in a container with a smaller one wedged in. My question is, what have people seen or made that works well underwater?

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Thinking about an underwater cache. A container that would sit on a sunken island in a lake. Maybe four feet deep. An idea I saw involves concrete in a container with a smaller one wedged in. My question is, what have people seen or made that works well underwater?

When this came up before, people said it's tough to keep a container dry, so you need a log that can handle being submerged in water.

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I've seen an ammo can work well underwater when the seal is in good condition. I've also seen the same ammo can fail miserably when someone caught a plastic bag between the lid and the lip of the ammo can when closing it; the plastic bag wicks moisture into the ammo can, no matter how good the seal might be without the plastic.

 

I've seen various double container designs that I think would work well, if they were replaced correctly by those who find them. One example uses PVC pipe for the outer container, with a cap at the top end and a ball valve at the bottom end. The ball valve is big enough for a preform to fit inside. When the cache is anchored in place, the air pressure inside the PVC pipe keeps water out even if the ball valve isn't completely closed. And if the preform is oriented with the cap up, then its unlikely that the water would reach the cap. So even if both the ball valve and the preform cap leak, the contents of the preform shouldn't get soaked.

 

Another approach is to give up trying to keep the cache contents dry. Drill holes in the container so water can flow in and out freely, an use a waterproof log, such as a diver's slate.

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Every underwater container we've found had water in it. Most were FTFs.

 

We have a paddle-to cache (dry land to access), and the ammo can container was submerged 4' for about six months during a flood of the area.

After wiping the container and drying my hands before opening, everything inside was still bone dry.

- We can't get cachers to use umbrellas to keep containers dry in rain, what do you think they'd do for an underwater one? :laughing:

 

Like niraD said earlier, a Reviewer posted here once, saying he used an ammo can with holes drilled through it, with a divers slate as the log.

I thought it was a good idea.

Edited by cerberus1
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Thinking outside the square, how about making it a two-stage multi, with the coordinates of the dry-land final written (or engraved) on the underwater object.

+1

We did one (only a few found it) that was a rusted, thick steel plate with coords to the next stage plasma-cut through it.

Just laying in a foot of water in a creek, with other similar old bridge parts.

Evil.

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Use a soda bottle preform, with a wire tether, attached to a suitable weight (brick, concrete block etc.) If it tethered such that the opening is kept facign down, water leakage should not be a problem.

 

I have used preform for several underwater caches with no issue.

 

You could use rite-rain paper for extra safety.

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