What is a dive plan on a shallow wreck?

[The Chairman]

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.

It's OK. My first instructor never got into the water with us. Yelled at us from the side of a pool and then let us dive without him in a blackwater lake. Of course, he wasn't a 'real' instructor with a diploma. Just a Master Cheif diver who had no idea how to teach. I didn't have a guide for over 30 years and I never died.

Know your limits. Respect your limits. Go explore.

 

[tursiops]

Advanced Open Water with Navigation as one of the modules.

Navigation is a required module for AOW.

 

[60plus]

Bit of a strange question because you need a plan whatever the depth or situation. For me there are two parts to a plan.
Firstly what you intend to do and how to do it.
Secondly what are the procedures when something goes wrong and the plan has to be abandoned.

 

[Robert H. Diver]

My plan is usually to have fun and also make it back to the boat LOL.

 

[mdwalter]

Time is usually set by the boat and/or NDL. Most boats allow an hour, but the deeper you go, the less time you can stay safely. For planning, I use the rule of 120. I subtract my anticipated depth from 120 and get a rough idea of how long I can stay. 75ft? 120-75=45 minutes. Of course, your PDC will guide you far more accurately.

...​

If I hit my time limit before all others, well it's still time to thumb the dive and start up.

So on a 130' dive you get out ten minutes before you got in?

 

[The Chairman]

So on a 130' dive you get out ten minutes before you got in?

Good troll. I learned that rule back in the sixties before I even got a depth gauge many years later. Limits have limits. Some are useful only to determine if what your PDC is telling you is even sane when you're planning. Many divers have no idea off the top of their head just how long they can stay at a certain depth, and the rule of 120 starts them in the right direction especially for a "shallow wreck" as stated in the OP. You can't stay long at 130FSW, and that's a depth better suited to tech diving. At least for me.

 

[Open Ocean Diver]

Dive with a guide familiar with the wreck you’ll see more.

 

[Outbound]

The viz was super low, probably 12'...

Man, I envy folks who can call 12' viz "super low."

Seems that you and your son did pretty well overall. For the wrecks we dive on around me (Great Lakes), dive planning can be very simple for the smaller and shallower wrecks and more detailed for the deeper or bigger ones. For one of the tugs we dive on the plan is usually "circle the thing a few times until we either get cold or bored, then come up." But it's a small boat and sits in about 50' of water, and we dive together all the time so we know how much gas each guy tends to use, etc. For the bigger wrecks we'll plan according to NDL times and gas.

Several have mentioned the importance of having a compass and knowing how to use it for underwater navigation. This is definitely critical. However, in your situation even if you had taken a bearing from the mooring line to the wreck it wouldn't have done you much good unless you took note to remember exactly where on the wreck that bearing landed you. Otherwise, if you hopped off the wreck and headed back on your reciprocal you could've easily swam on a parallel course and missed the mooring line completely. Next time, spend a bit of time when you arrive at the wreck to make a mental note of where you are on it. Bow? Stern? Amidships somewhere? Is the hull keeled over, and if so, which side is it resting on? Is there a damaged section, specific coral or sponge growth, or any other marking that can help you to navigate your way back? Be particularly careful on wrecks that have split apart and are in sections, as in low viz it can be easy to get confused and think you are on one section when you are actually on another. Pay careful attention to the dive briefing and, as you do the dive, picture where you actually are on the wreck and how to get back to the mooring line. Underwater navigation is about much more than simple compass bearings.

 

[ScubaWithTurk]

My first thought is learn how to determine what your RMV is (Respiratory Minute Volume) and then covert that to SAC (Surface Air Consumption), sometimes referred to as Surface Gas Consumption. Once you have that number, then and only then can you accurately plan a dive based on two determining factors, your NDL and your gas volume. If you need any help with that, feel free to shoot me a PM and I will walk you through it.

On a side note, I am really shocked more agencies don't teach this type of dive planning in the OWC.

 

[Wibble]

Good troll. I learned that rule back in the sixties before I even got a depth gauge many years later. Limits have limits. Some are useful only to determine if what your PDC is telling you is even sane when you're planning. Many divers have no idea off the top of their head just how long they can stay at a certain depth, and the rule of 120 starts them in the right direction especially for a "shallow wreck" as stated in the OP. You can't stay long at 130FSW, and that's a depth better suited to tech diving. At least for me.

Those rules of thumb are extremely useful in assessing a dive. You'll know more or less what the gas would be; bottom time; min gas; deco gas; contingency gas, etc. For most dives -- non extreme dives! -- that's all the planning you'd need, you just run it on your computer(s).

Maybe just call it experience?