Underwater caches

[irenfrea]

Hello everyone, first post in the forums, I'm getting started on GC and I'm planning an underwater cache to be placed in an artificial lake on a park near my home. However I'd like to hear some advice from veteran geocachers about underwater caches. I'm planning to use a big bottle as the cache, with some stones in the inside for ballast, assuming that the bottle is airthight (im going to test it somewhat soon) do you think it will last?

[aniyn]

Relevant thread

Bottles can work, you just need to be sure they'll sit up-side down when they're underwater. Unfortunately, the bottles stop being water tight every time someone opens then. People are unfortunately more of a problem than the containers themselves.

[irenfrea]

Thanks for the advice, its true, probably someone wont close the bottle tight enough, I'll make some testing on a friends pool btw

[+StarBrand]

What is the bottle made of?? What kind of seal?

 

The best ones I know of typically use an ammocan with something like a lock-n-lock and rocks inside. Double secure.

[+briansnat]

I think one method to consider would be to hide the actual cache on dry land, then put the coordinates to the cache on something waterproof (e.g. painted on a rock, etched on plastic) and sink that underwater.

[irishgond]

Have you heard of the beer Grolsch? Some of the bottles have lock tops on them that seal great, maybe for a micro....just a thought ;-)

 

http://blastmagazine.com/images/media/PL_s...op_bottleLR.jpg

[+Crafty Turtle]

I'm thinking that a container designed to keep a liquid IN, would be equally as suitable to keep water OUT. ...pressure of depth notwithstanding.

 

So, a screw-top container (jar, bottle, canister, etc) would be ideal.

 

I too am planning an underwater cache, and I'm using a diver's box. Obviously this is designed to keep water OUT, under pressure. Maybe it's overkill, but it depends how deep you are putting the cache. Anything over 10 feet or so, and it'll be under enough pressure that an ordinary plastic screw-top canister might get compromised. If you put it just under the surface, it'll be out of site in murky water, or amongst reeds or rocks. (Of course it goes without saying - keep it safe.)

 

I also like the idea of doubling up - one container inside another, to be sure.

 

I think your idea is great! How many people would drive or walk past your lake every day, and not realise there's a cache there?

[irenfrea]

Well it is a 6 litre bottle with a big opening (about 3.5 cm wide) and screw top, theyre made of PET as far as I know. I'll probably add a cover for the top made with a latex balloon for extra sealing, the idea is to drop this one in an artificial lake from a boat, since the lake is located in a park which rents small rowing boats, and tie a wood piece from a line of nylon string (like those used on fishing lines) so it will float and mark the cache site (since you can normally find tree branches and the such floating in this lake i guess it will pass unnoticed). The cache hunter will have to rent a boat to get to the cache site, which may make it extra fun to find

Edited October 2, 2009 by irenfrea

[+Crafty Turtle]

Sounds like a lot of fun. Very exciting for families too.

 

Make sure you inform ppl on the cache page the cost of boat hire, as well as their hours of operation. ...without sounding like commercial advertising.

[+Wildbill34275]

Well it is a 6 litre bottle with a big opening (about 3.5 cm wide) and screw top, theyre made of PET as far as I know. I'll probably add a cover for the top made with a latex balloon for extra sealing, the idea is to drop this one in an artificial lake from a boat, since the lake is located in a park which rents small rowing boats, and tie a wood piece from a line of nylon string (like those used on fishing lines) so it will float and mark the cache site (since you can normally find tree branches and the such floating in this lake i guess it will pass unnoticed). The cache hunter will have to rent a boat to get to the cache site, which may make it extra fun to find

 

So if I understand this right, you are going to use a weighted bottle for the actual cache and attach it to a piece of wood as a marker. If you don't secure it in place somehow the wind and or any currents will cause it to float around and it won't be at GZ. If you just tie it to a low hanging branch it will stay in place

[+TeamAH3]

Well it is a 6 litre bottle with a big opening (about 3.5 cm wide) and screw top, theyre made of PET as far as I know.

That's quite a lot of volume - you're going to need nearly 15lbs of weight to keep that sitting underwater and more like 20 to ensure that the floating wood can't drag it around in the wind. That's a lot of stones small enough to fit in the bottle - don't fancy tipping out the goodies and rocks into a boat much either. You might be better considering a smaller cache.

Edited October 8, 2009 by TeamAH3

[+theosus]

Well it is a 6 litre bottle with a big opening (about 3.5 cm wide) and screw top, theyre made of PET as far as I know.

That's quite a lot of volume - you're going to need nearly 15lbs of weight to keep that sitting underwater and more like 20 to ensure that the floating wood can't drag it around in the wind. That's a lot of stones small enough to fit in the bottle - don't fancy tipping out the goodies and rocks into a boat much either. You might be better considering a smaller cache.

 

Wal-mart has lock-and-lock style camping boxes that are small and have a waterproof o-ring. That might be easier to submerge - tied to a half cinder block or something. I would also remember, the deeper you put it the more pressure there is. Just from swimming you can tell theres a lot more pressure 8 feet down, than just under the surface. I would suggest only non-water-soluble swag/materials. I have seen a cache that had no log book - only numbers on a metal tag. You had to email the numbers to the cache owner - or he would delete your log. That might be a non-logbook alternative, in case your seal is compromised. Maybe a travel bug tag would work...

You want to make sure a cache of this type is as easy to maintain as possible. Nothing would suck like having to go swimming in february to retrieve your cache because it filled with water and sank.

[+TEAM HARTSOCK]

Ball currently makes these freezer cup type things which has a screw on lid. Have a normal cache in one of them and it is holding up just fine. I am now working on an underwater cache that is to go in a stream/pond nearby which is one of these containers that is going to go inside of a 4" PVC pipe which is painted like a log and has some add on stuff that will ensure it doesn't look like a PVC pipe. One end of the pipe will have an end cemented in place with weight at that end to ensure it stays submerged and the other end will have a screw off clean out end to reveal the cache. So far the initial tests have proven promising.

[+niraD]

To submerge a container with concrete, you have to fill it about half full. To submerge a container with rocks, you're going to need to fill it at least half full of rocks. If the rocks are loose, then it will be hard to find the log/swag among the rocks. Of course, you could always use something that is more dense than concrete or rocks, and that would take up less of the container's volume.

 

A bottle like you describe would be more waterproof if you could secure it in place upside down, with the lid down and the bottom of the bottle up. Then the air pressure inside the bottle would keep the water out if the seal isn't 100% watertight.

 

I have seen a cache that had no log book - only numbers on a metal tag. You had to email the numbers to the cache owner - or he would delete your log. That might be a non-logbook alternative, in case your seal is compromised.

Keyword caches are no longer allowed. Requiring confirming information from the finder is now considered an Additional Logging Requirement, and is no longer allowed.

 

But you can make a multi-cache, where the clue that provides the coordinates for the final is underwater. That way you have the fun of the underwater search, but the cache can be on dry ground.

[+TeamAH3]

As an afterthought - you can normally pick up secondhand diver's weights (ie lumps of lead) cheap via ebay or similar. These are far better for weighting than rocks as they'll take up much less space.