PLBs Can Save Your Life

[Dan]

I don't think that is how the physics works. Imagine an upside-down glass that you lower into the water. You can take it down to (say) 10m, and the air will compress to half the glass, water will fill the other half, and the pressure in the air is ambient at 10m...2 ATM. the key is that the air is at the top, so anything there will still be dry...but under full pressure. Now if the water can only go slowly into the upside-down glass...a slow leak....then the pressure in the air will slowly increase from 1 to 2 ATM. So the key is to have a slow leak, so the pressure in the canister increases slowly...you might still end up with ambient pressure in the canister, depending on the orientation of the canister and whether the air can get out.

How did my GoPro Hero 6 survive at 100’ depth with half full of water in the case then?

 

[tursiops]

How did my GoPro Hero 6 survive at 100’ depth with half full of water in the case then?

If salt water got into the camera, I have no idea how it survived. The pressure is irrelevant. The flooding problem is salt water...not pressure. Pressure is just what lets the salt water get in.

 

[seeker242]

If salt water got into the camera, I have no idea how it survived. The pressure is irrelevant. The flooding problem is salt water...not pressure.

The pressure is relevant when it's waterproof down to a particular pressure, like all PLBs are. Hero 6 for example, waterproof down to 33 feet IIRC. Exceed that pressure, no longer waterproof.

 

[tursiops]

The pressure is relevant when it's waterproof down to a particular pressure, like all PLBs are. Hero 6 for example, waterproof down to 33 feet IIRC. Exceed that pressure, no longer waterproof.

Agreed. But what kills the camera is the saltwater, not the pressure. Having a 33 ft rating just means you can tolerate a bit more pressure before the saltwater gets in.

 

[DandyDon]

The pressure is relevant when it's waterproof down to a particular pressure, like all PLBs are. Hero 6 for example, waterproof down to 33 feet IIRC. Exceed that pressure, no longer waterproof.

I think both are true.

Agreed. But what kills the camera is the saltwater, not the pressure. Having a 33 ft rating just means you can tolerate a bit more pressure before the saltwater gets in.

Dan's camera like my PLB both got wet in salt water when some water got inside the canisters, but pressure inside did not exceed tolerances, rated to 33 feet but actually a little more. We got lucky.

I wasn't so lucky when I emptied my pockets into my hat on the beach after digging out baby turtle stragglers

and getting wet sand all over my clothes. I went in the ocean to rinse off, then realized my land camera was still on my belt. I saved the batteries and card tho.

 

[outofofficebrb]

I wanted to come back and share what the ACR PLB-425 View, UST floating signal mirror, and an emergency blanket (shade!) looks like together in the HDVSEATEK small canister. It fits perfectly and there’s still space for something else small.

 

[outofofficebrb]

Does anyone know what size, material, and durometer the o-ring is on the HDVSEATEK canister is? I tried e-mailing the person who makes it but haven't received a response yet and want to ensure I have a spare since I'm leaving on a trip soon.

Thanks.

 

[-JD-]

I wanted to come back and share what the ACR PLB-425 View, UST floating signal mirror, and an emergency blanket (shade!) looks like together in the HDVSEATEK small canister. It fits perfectly and there’s still space for something else small.

How easy is that to open up after it has been sealed for a while and does the O-ring on that canister seal by compressing

vertically between the outer flanges
| | __
| Top | | |
-------- | |
ORing| |
--------| |
|Bot |


or circumferencially between an inner and outer surface
| | __
| | | |
| Top | ORing | Bot |
| | | |
| | thread | |
| | thread | |
------- | |
-----------------| |
| |


Sorry for the crude character graphics.

Background: I've been testing an old Under Kinetics dive light with the guts removed as a possible canister. It uses a single ORing with a vertical compression design and it becomes almost impossible to open up once it is cranked down to seal. I'm trying to see if it is characteristic of that type of seal or is particular to the UK implementation.

Thanks!

 

[tridacna]

How easy is that to open up after it has been sealed for a while and does the O-ring on that canister seal by compressing

vertically between the outer flanges
| | __
| Top | | |
-------- | |
ORing| |
--------| |
|Bot |


or circumferencially between an inner and outer surface
| | __
| | | |
| Top | ORing | Bot |
| | | |
| | thread | |
| | thread | |
------- | |
-----------------| |
| |


Sorry for the crude character graphics.

Background: I've been testing an old Under Kinetics dive light with the guts removed as a possible canister. It uses a single ORing with a vertical compression design and it becomes almost impossible to open up once it is cranked down to seal. I'm trying to see if it is characteristic of that type of seal or is particular to the UK implementation.

Thanks!

I found it impossible to open after compression.

 

[DandyDon]

Brb, replacing the o-ring ever year or so is a good idea, and I hope that someone comes up with a good US source. I bought a couple from Hdvseatvek, shipped from Australia, for $12. More important is regreasing the o-ring. Mine leaked a little the first day on my last trip, no harm but not something you’d want to happen every day. I added a little silicone grease which fixed that for the rest of the week. I do open and check daily, good idea for any canister.

JD, I think you just want it snug as well as greased with silicone grease. Check daily as to ease of opening and leaked.