What is a dive plan on a shallow wreck?

[DogDiver]

Aside from being an overhead dive where there’s no immediate access to the surface, there’s little or nothing in common between wreck diving and cave diving.

The first thing about wrecks is they’re ever changing and full of entanglement opportunities and pieces easily break off. Wrecks are seldom deep penetration dives and much of the hard and fast caving rules certainly don’t apply.

Caves don’t generally change shape unless the water level rises with rain. Their basic topology may not have changed in thousands of years. Wrecks change with each passing storm and decay. In many ways wrecks are more akin to diving in mines than caves as in the environment can rapidly change — a rotting pit prop gives way.

The generic rules of caving — continuous line, rule of thirds or less — generally don’t apply to wrecks as penetration tends to be short. Wrecks demand common sense and good core skills as they normally have a lot of silt, obviously this applies to many caves too.

The challenge with wrecks is finding the fine line of exploring the marine architecture without putting yourself in danger. Most wartime wrecks are now collapsing and offer limited long penetration opportunities. Looking at the props, boilers, engines, bow, etc.

I’ll agree to disagree with you on this. I did 36 years of Great Lakes Wreck diving. In the late 90’s a group of us went to Florida and got cave certified so we wouldn’t kill ourselves in the wrecks. Back then wreck diving was based on progressive penetration and running a line in a wreck would kill you. We were doing deep and long wreck penetrations and I can tell you for a fact that being cave trained saved myself and buddy lives more than once.

 

[boat sju]

I believe @lamont "rock bottom rule of thumb" was (depth x 10 ) + 300 . And the max depth for an 80 cu. ft. was 80 ft, 100 ft for a 100 cu.ft. tank, etc.

@allanbranch, There's a lot of past discussion on rock bottom gas planning that you might find interesting. I just quoted an easy rule of thumb from one.

@The Chairman uses +50 but he has a bit more experience than you do.

 

[Wibble]

I’ll agree to disagree with you on this. I did 36 years of Great Lakes Wreck diving. In the late 90’s a group of us went to Florida and got cave certified so we wouldn’t kill ourselves in the wrecks. Back then wreck diving was based on progressive penetration and running a line in a wreck would kill you. We were doing deep and long wreck penetrations and I can tell you for a fact that being cave trained saved myself and buddy lives more than once.

Of course there’s the long penetrations in recent or well preserved wrecks which have a lot in common with cave diving.

For every one of those there’s dozens of collapsing wrecks where penetration is short if at all possible.

 

[The Chairman]

@The Chairman uses +50 but he has a bit more experience than you do.

Of course, this is for recreational limits only. Most of my personal diving involves the rule of thirds or a variant thereof.

In the days of yore, before I could afford (or wanted) an SPG, I awaited the first pucker when my air ran out. Then, I would simply pull the lever rod of my J-Valve to initiate my reserve air. Every now and then, I would experience the second pucker, which was always far more exciting, when I realized that the lever was already down and I had to get to the surface without that reserve. It should be noted that the pucker you felt as you tried to suck the air out of an empty tank, leveraged a much larger pucker at your other end.

 

[Nick_Radov]

Got a little worried and locked arms...then slowly ascended to 35' watching our dive computers for accent rate.

Locking arms isn't recommended. This screws with your buoyancy control and leaves you short of a hand that you need for other tasks. If you're holding on to another diver, then it's easy to accidentally get too positive or too negative without realizing it. Then if you lose your grip, you go suddenly shooting up or down while your buddy goes the opposition direction. While ascending it's best to stay close but not actually touching.

 

[Orestis82]

Wait, you are OW and the top of the tug is at 55’? So already you are close to your certification limit. Of course there’s nothing preventing you from going deeper and seeing the other end of the boat but best to avoid this kind of temptation.

 

[The Chairman]

Meh... 60ft is the deepest an instructor can take an OW student. I don't see it as a viable limit.

 

[boat sju]

Wait, you are OW and the top of the tug is at 55’? So already you are close to your certification limit. Of course there’s nothing preventing you from going deeper and seeing the other end of the boat but best to avoid this kind of temptation.

And this coming from a guy with less than 25 dives who just started a thread about accidentally exceeding his NDL on a 30m dive.

 

[Orestis82]

And this coming from a guy with less than 25 dives who just started a thread about accidentally exceeding his NDL on a 30m dive.

I’ll take the bait. Did I say something wrong?

 

[Orestis82]

Wait, you are OW and the top of the tug is at 55’? So already you are close to your certification limit. Of course there’s nothing preventing you from going deeper and seeing the other end of the boat but best to avoid this kind of temptation.

Let me rephrase so that I don’t come off as condescending or over-confident. I, personally, wouldn’t make this dive without a guide. Not now, not when I had 12 dives post OW. I’ll let more experienced people give advice.