underwater cache -> Howto?

[Guest wetbell]

Hi all, I am planning on making an underwater cache. I know that underwater thet tupperware will not hold very long so I plan on using sewer-pipe. Does anyone know if this is water-tight enough?

The next problem is the gps-unit. One could go by boat and leave the unit in there dry but as this place is enclosed water not so many boats are available (no rentals either) so I want to make it reachable for swimmers. Would a triangular fix be acceptable for geocachers? I think of giving 2 pairs of coordinates. so that lines through them will cross in the water, swim there and duckdive...

[Guest k7pbx]

Have coordinates to a spot, then swim west 30'. Or what ever direction from coordinates.

[Guest peter]

I would just give the coordinates of the cache and leave it up to the searcher to decide how to find it.

Some searcher options would be a) use a waterproof GPS, put the GPS in a waterproof case, c) plot location on a topo map and then determine compass bearings from cache site to landmarks like peaks, towers, pts. of land, etc. - swim out with compass until bearings match, d) find natural ranges that cross near cache site on topo map , e) determine bearing and distance from point on shore using topo map and swim out that distance while maintaining compass bearing, f) lots of other possibilities

[Guest BasicJim]

When I whitewater kayak, I use a drybag. I am sure that you could see through it to read your GPS. Give that a shot.

[Guest mcb]

The dry bag would keep your GPS dry but I am afraid that if you go much deeper that a few inches the satellite signal will be to weak to maintain a lock. I did see a discussion on the sci.geo.satellite-nav and if you could figure out how to seal the connections at the GPS unit you could put an external antenna on a small buoy and float it above you while you dove down and hid the cache. You would just have to ensure that you little buoy stayed directly over head because your unit will give you the position of the antenna not the unit. Good luck

 

mcb

[Guest mcb]

The dry bag would keep your GPS dry but I am afraid that if you go much deeper that a few inches the satellite signal will be to weak to maintain a lock. I did see a discussion on the sci.geo.satellite-nav and if you could figure out how to seal the connections at the GPS unit you could put an external antenna on a small buoy and float it above you while you dove down and hid the cache. You would just have to ensure that you little buoy stayed directly over head because your unit will give you the position of the antenna not the unit. Good luck

 

mcb

[Guest wetbell]

I was wondering, as I want the cache reachable to swimmers I could just drop a weight with a little float on a 1 meter line(for easy finding) from the selected location. After that I duckdive to hook-up the stash to the weight.

Stumblers are not likely I suppose if the water is murky enough to prevent the float to be seen from the surface.

 

This only leaves the question about a pressure-proof container. any ideas?

 

Anyone ever found a waypoint to an underwater stash?

 

WetBell

[Guest Silver]

Here's some ideas you might try.

 

1. Find out how deep the water is where you want to stash the cache. Get some nylon rope (yellow water skiing rope works well) that is longer than the water is deep. One end will be a heavy weight with an eyebolt or ring, the other end tie to a float.
2. About 1 meter from the float, tie two plastic clips (plastic carbiners) to the rope. One clip will clip to the cache container, the other will clip to the weight when you submerge the cache. This way the swimmer can unhook the clip and both the cache and the float will rise to the surface.
3. The swimmer can now unclip the cache, take it to the boat or shore and sign the log, trade items, and seal it again. Then they take the cache back to the float, clip the cache container to its clip, and submerge the cache and float back to the weight. Because they will have to submerge them both to the weight, the float and the cache container should not be too big. Ever tried to hold a beachball under water?
4. The cache could be made from either a scuba dry box(Pelican makes some good ones), or you could make one yourself. Take something like a plastic pretzel container. (They are about 12 inches tall and 9 inches in diameter.) Drill a small hole in the lid and put an eyebolt through with flat metal washers on both sides. Between the metal washers and the plastic lid, place rubber gaskets/washers and tighten securly. Cover all around the washers with silicon sealent. You might also make a rubber seal for the lid where it contacts the mouth of the container.
5. If the items you place in the container are not too heavy, it should float mouth down, minimizing the water intrusion. I would fill the finished container with something about the same weight as the final cache contents. Maybe golf balls, drinking glasses, anything that getting wet won't hurt. Fill the rest of the container with newspaper and submerge it down to the depth you plan on stashing it. Leave it a week and then retrieve it. If the newspapers haven't gotten wet, you can probably guess you have a watertight cache.

 

These are just some ideas. Experiment! If you find a winning combination, let the rest of us know. Good luck!

 

Silver

PADI Instructor

[Guest Silver]

Here's some ideas you might try.

 

1. Find out how deep the water is where you want to stash the cache. Get some nylon rope (yellow water skiing rope works well) that is longer than the water is deep. One end will be a heavy weight with an eyebolt or ring, the other end tie to a float.
2. About 1 meter from the float, tie two plastic clips (plastic carbiners) to the rope. One clip will clip to the cache container, the other will clip to the weight when you submerge the cache. This way the swimmer can unhook the clip and both the cache and the float will rise to the surface.
3. The swimmer can now unclip the cache, take it to the boat or shore and sign the log, trade items, and seal it again. Then they take the cache back to the float, clip the cache container to its clip, and submerge the cache and float back to the weight. Because they will have to submerge them both to the weight, the float and the cache container should not be too big. Ever tried to hold a beachball under water?
4. The cache could be made from either a scuba dry box(Pelican makes some good ones), or you could make one yourself. Take something like a plastic pretzel container. (They are about 12 inches tall and 9 inches in diameter.) Drill a small hole in the lid and put an eyebolt through with flat metal washers on both sides. Between the metal washers and the plastic lid, place rubber gaskets/washers and tighten securly. Cover all around the washers with silicon sealent. You might also make a rubber seal for the lid where it contacts the mouth of the container.
5. If the items you place in the container are not too heavy, it should float mouth down, minimizing the water intrusion. I would fill the finished container with something about the same weight as the final cache contents. Maybe golf balls, drinking glasses, anything that getting wet won't hurt. Fill the rest of the container with newspaper and submerge it down to the depth you plan on stashing it. Leave it a week and then retrieve it. If the newspapers haven't gotten wet, you can probably guess you have a watertight cache.

 

These are just some ideas. Experiment! If you find a winning combination, let the rest of us know. Good luck!

 

Silver

PADI Instructor

[Guest trilobites]

Try and find a well driller in your area. There is a flush threaded PVC pipe that is used extensively for monitoring wells that has o-rings. You can buy it in a short as 1-2-1/2 foot lengths. Just remember that when the high water comes the cache may be gone.

[Guest ggaspari]

Ok, here is the mega-ultra-pro Plus Advanced Version XP (whoops) Underwater-Howto...

 

Serious now: first thing is to really waterproof your items. I suggest using TWO rugged plastic bags (in case one of them get punctured), take off (like, SUCK ) the air using a flexible thin hose (medical equipment like those used in venous lines work well in this case), and most important: instead of just tieing the opening, TWIST it a couple times, fold it over itself and use a strong rubber band to fix it (a piece of a tyre air chamber should do it).

 

After that, using tupperware, ammo boxes or anything like that should do, because, even if the outer box gets flooded (most certainly will do), the contents will be protected, and easily opened once taken out of water - and since there's no hot-sealing/stapling/glueing/etc involved, the process can be redone.

 

Other thing that should be considered is the strength of water currents. In that case, putting some kind of weights (rocks, metal, etc) can solve the problem.

 

As for how to take readings, even some entry-level GPS receivers like the eTrex are water-resistant or waterproof, but if not, you can use the same technique described above

 

 

[This message has been edited by ggaspari (edited 25 August 2001).]

[Guest ggaspari]

Ok, here is the mega-ultra-pro Plus Advanced Version XP (whoops) Underwater-Howto...

 

Serious now: first thing is to really waterproof your items. I suggest using TWO rugged plastic bags (in case one of them get punctured), take off (like, SUCK ) the air using a flexible thin hose (medical equipment like those used in venous lines work well in this case), and most important: instead of just tieing the opening, TWIST it a couple times, fold it over itself and use a strong rubber band to fix it (a piece of a tyre air chamber should do it).

 

After that, using tupperware, ammo boxes or anything like that should do, because, even if the outer box gets flooded (most certainly will do), the contents will be protected, and easily opened once taken out of water - and since there's no hot-sealing/stapling/glueing/etc involved, the process can be redone.

 

Other thing that should be considered is the strength of water currents. In that case, putting some kind of weights (rocks, metal, etc) can solve the problem.

 

As for how to take readings, even some entry-level GPS receivers like the eTrex are water-resistant or waterproof, but if not, you can use the same technique described above

 

 

[This message has been edited by ggaspari (edited 25 August 2001).]

[Guest Uplink]

Wouldn't it be easier to just use cache items that are ok to get wet (a flooded cache)? You might have to have a vertual log. Also, I think you would have to target Scuba divers - an underwater search, even if you had a + or - 20 foot fix, could be an exhausting job, and untrained or underequiped folks can get into trouble very quickly. And if you are going to make a neutrally bouyant cache, you did plan on anchoring that, didn't you? I thought about putting a cache in a crab trap, but concluded the float would make it too easy to find.

[Guest CACHED-AWAY]

My second cache I placed was in a military flare can ...it's an over sized ammo can with a rubber gasket.I took it from about 1000' to about 5500' and opened it and heard a WHOOSH...seems to be airtight might be watertight too..you can find these at surplus stores for about 7.50

Cached-Away

[Guest Cape Cod Cache]

I used to do a game years ago from S FLA to the Bahamas, we used to hide bottles of rum. I have a thought about GPS usage (as opposed to LORAN etc... I have a couple caches on/near Bass River MA, USA. A bit of pvc pipe with coordinates, and then a land travel. Thinking of a bunch of small units, that a skin diver can get to. Cut one off, replace it.