Underwater Cache - Any Ideas?

[Laighside Legends]

I am planning to place a underwater cache this summer

Does anyone know what containers work/don't work?
I am thinking of using a piece of PVC pipe with a screw lid attached to one end. This is then anchored to the seabed using a old wheel rim.

Do PVC screw lids seal well?

Any suggestions on what I should use?

[caughtatwork]

The best one I've seen does not make the cache water tight but uses an underwater tablet and an underwater pen (pencil?) for your log. Then there is no possibility of leaks, but of course, no swaps.

[Richary]

Without having done one, I think a problem with trying to make something watertight is that as it is removed from the water for the swapping/signing process, it will come out wet. Some of this water will invariably get inside the container each time it is found, and things will end up damp. That assumes too that the finder does the thing up properly allowing it to seal.

I also have some concerns about dumping a wheel rim onto the ocean floor. Doesn't really keep with the environmental ethos of the hobby (you would be best using something already there like an old mooring point for a buoy or similar).

[Laighside Legends]

Without having done one, I think a problem with trying to make something watertight is that as it is removed from the water for the swapping/signing process, it will come out wet. Some of this water will invariably get inside the container each time it is found, and things will end up damp. That assumes too that the finder does the thing up properly allowing it to seal.

I can see this as been the biggest problem - possibly making the cache bigger might help (this would also make it harder for finders to re-submerge it though)

I also have some concerns about dumping a wheel rim onto the ocean floor. Doesn't really keep with the environmental ethos of the hobby (you would be best using something already there like an old mooring point for a buoy or similar).

I know of many existing old mooring points (which are made from old wheel rims) and I will probably use one of them.

The best one I've seen does not make the cache water tight but uses an underwater tablet and an underwater pen (pencil?) for your log. Then there is no possibility of leaks, but of course, no swaps.

I like this idea as I don't intend to include swaps (but TBs would be good). How long does the writing last on them? ie. does it slowly wash off with lots of small sea creatures crawling over it and been underwater for extended lengths of time?
How much writing area is on them? ie. How long will it last before needing replacement?
How much do they cost and where can you get them from?

[caughtatwork]

Don't really know. I only found it once

http://cgi.ebay.com.au/NEW-UNDERWATER-W ... 51942a0f46

Can be easily cleaned with Jiff or other household cleaner.
12.5cm x 15cm overall.

Dunno. Might be worth a squiz around at a dive shop or something similar.

[Zytheran]

Rather than using ink/pencil/whatever use a stack of very thin aluminum tags and a hard plastic stylus if you are concerned about water.
As for container I have done one. 100mm PVC water pipe with sealed end 2/3rds filled with rock and concrete to make overall buoyancy negative. (Or use lead if you have a few kg of it.) Remaining air space has a sports drink container which seals air tight which contains the usual logbook and swaps. Removable end is sealed pipe screw fitting with o-ring seal. Currently is sitting 3m below water level in an old mine shaft. Has been dry inside so far. An improvement would be a 50/60 PVC water pipe with o-ring seals for inner container rather than the sports drink container.
This is what it looks like with some recent finders.

[Laighside Legends]

Rather than using ink/pencil/whatever use a stack of very thin aluminum tags and a hard plastic stylus if you are concerned about water.
As for container I have done one. 100mm PVC water pipe with sealed end 2/3rds filled with rock and concrete to make overall buoyancy negative. (Or use lead if you have a few kg of it.) Remaining air space has a sports drink container which seals air tight which contains the usual logbook and swaps. Removable end is sealed pipe screw fitting with o-ring seal. Currently is sitting 3m below water level in an old mine shaft. Has been dry inside so far. An improvement would be a 50/60 PVC water pipe with o-ring seals for inner container rather than the sports drink container.

I like the aluminum tag idea (but wouldn't they rust very quickly in sea water?)
Did the PVC pipe fill with water leaving only the drink bottle to keep the log dry or did it all stay dry?
The advantage of having yours in a mine shaft is that the finders open and sign the log on dry land and hence there is no chance of water getting in while this is happening. Mine will be a reasonable distance from land and hence the log will need to be signed while in the water.

I am now thinking of having one PVC tube within a larger one. The larger outside one would have the aluminum tags in it and the small inside one would have the paper log (inside a plastic bag) and any TBs. Finders could then have a choice of using the aluminum tags or the paper log depending on weather they had a boat or other dry platform with them. The outside one would stay reasonably dry (minus a few splashes while opening and signing) and the inside one would stay totally dry.

Would this work?

[Zytheran]

Did the PVC pipe fill with water leaving only the drink bottle to keep the log dry or did it all stay dry?

PVC stayed dry inside, that was the design. The sports drink container was a backup.
Oh, one other thing, test the whole assembly in a river /rainwater tank/bath before putting out in the field.

[Richary]

And aluminium can't rust, rust is the reaction of iron oxidising. Aluminium will oxidise but only on the surface and it won't decay in salt water in a hurry I wouldn't think.

[Hoojar]

I have found a PVC pipe within a PVC pipe, however sadly it got washed away in a flood:

http://coord.info/GC10F28

Another that I sadly did not get a chance to find, and also did not stand the test of time:

http://coord.info/GC10F28

[Damo.]

I have found a PVC pipe within a PVC pipe, however sadly it got washed away in a flood:

http://coord.info/GC10F28

Another that I sadly did not get a chance to find, and also did not stand the test of time:

http://coord.info/GC10F28

They're both the same cache.....

[Hoojar]

They're both the same cache.....

Try http://coord.info/GCMP06

[gmj3191]

One of those solid glass preserving jars might make a good container.
Because they close on a rubber seal with a clamp like an ammo box, it might get around the
finder not closing it problem.
A huge bag of moisture absorbent might help with the dampness issue.
A recent one around here used divers weights as the anchor which seemed quite successful.

[covert]

Glass container for a cache is not a good idea. Broken glass and kids hands make a mess that is hard to get of the log book...

2 pieces of PCV pipe are a great way to go. One that fits inside the other. Ballast at one end with concrete.

[robmc]

I constructed mine with a 200ml Sistema. Removed the problem of getting things wet by drilling a couple of holes in the side and submerging (with a small weight attached). The log is made of white plastic film, and the pen is a graphite pencil (that is not a normal pencil made of wood, but a pencil made just of graphite). Both can be purchased from Art Suppliers for little cost..
Do not go to a Dive shop! They have an interesting idea of the value of their products. You probably won't like it!

Chewinprickles put some suitable swaps in, unfortunately the next person opened the container underwater, and they floated to the surface.
TB's and geocoins have been in it.

The cache does get some sand in it during winter storms, but all this does is clean the logbook ready for summer's finders.

If you want to know anything else, send me a note.