Question Dive planning exercise, please check my work

[scubadada]

And? So if tables give me 15 minutes bottom time, I still need to allocate some time for descent and need to leave a bit early. Yes you teleport yourself to the bottom/drop like a rock and you could execute a perfect 10 (or 20, depends on the table) meters per minute ascent right on the 14:59 mark but as a prudent recreational diver who want needs to avoid mandatory deco stops, you want to leave a earlier.

In reality, you follow your computer for a no stop dive, right? This takes your descent and bottom time into account. Then, you just do your normal ascent and safety stop. With a modern computer, you have the advantage of additional information like SurfGF.

 

[crofrog]

Casual recreational depth? Sure, in Egypt, warm water, infinite viz.

There is nothing wrong with deco. 10 mins of backgas deco on a single cylinder is fine, worst case you would need to breathe O2 for a bit back on the boat.

Until you have some sort of loss of gas issue and are blowing off 10 minutes of deco because you didn’t bring the right equipment or plan.

 

[johndiver999]

Until you have some sort of loss of gas issue and are blowing off 10 minutes of deco because you didn’t bring the right equipment or plan.

Casual recreational depth? Sure, in Egypt, warm water, infinite viz.

There is nothing wrong with deco. 10 mins of backgas deco on a single cylinder is fine, worst case you would need to breathe O2 for a bit back on the boat.

Exactly, the whole reason deco is a big deal is that you can't just surface.

What if the diver experiences a bad freeflow or a scuba failure at the end of the dive? Running for the surface ASAP from 120 with 10 minutes of deco could result in paralysis or maybe worse. To suggest the worst case scenario is owing the capt $20 to refill his o2 bottle, is way, way off target.

I would carry a pony bottle for this dive, with enough to probably hang for a good 5 minutes, at least, even if the dive was planned for nodeco.

Diving to 120 feet on nitrox or air is not a big deal, but suggesting that blowing off 100% of a 10 minute deco stop is trivial, is irresponsible

 

[grantmac]

Would make a very good AN/DP dive. Even finding the wreck within Nitrox NDL might be challenging.

 

[Cthippo]

Would make a very good AN/DP dive. Even finding the wreck within Nitrox NDL might be challenging.

Doing it as an AN/DP dive would involve adding a second deco gas and intentionally going into deco, correct?

I'm not worried about finding the wrecks. I should be able to drop a line directly on them and follow it down.

 

[Cthippo]

Exactly, the whole reason deco is a big deal is that you can't just surface.

What if the diver experiences a bad freeflow or a scuba failure at the end of the dive? Running for the surface ASAP from 120 with 10 minutes of deco could result in paralysis or maybe worse. To suggest the worst case scenario is owing the capt $20 to refill his o2 bottle, is way, way off target.

I would carry a pony bottle for this dive, with enough to probably hang for a good 5 minutes, at least, even if the dive was planned for nodeco.

Diving to 120 feet on nitrox or air is not a big deal, but suggesting that blowing off 100% of a 10 minute deco stop is trivial, is irresponsible

I would definately do this with a 40 pony. Even assuming a total loss of back gas at 120, that will give me at least 15 minutes at 20 feet, after ascending from depth.

 

[rjack321]

AOW here in the Great Lakes is a common dive to these depths, with single tank, including just air (though there is a better nirtox mix if your training allows it)....

You don't get to see much or have much bottom time, so that alone explains that this type of diving is best done with advanced training, but it can be done within recreational limits...

Vis in the Great Lakes is 100x Lake Washington, its 8ft on a great day. 5-6ft on average, less where your shot impacts the silt.

Doing it as an AN/DP dive would involve adding a second deco gas and intentionally going into deco, correct?

I'm not worried about finding the wrecks. I should be able to drop a line directly on them and follow it down.

Which are you thinking of here? MANY divers have missed the wreck and end up in a silt bomb in the bottom. Have you done any diving in Lake WA before? Which wrecks?

'Cause this is NOT how to dive Lake WA. We never just drop shots on any Lake WA wreck. This is how they get hammered and trashed. Punching holes in the fabric of the planes, breaking off wood from the boats. You need to be setting a shot line near but NOT on the wreck. Some of them are incredibly fragile. Then using a spool and a compass to connect the shot to the wreck.

Honestly if you haven't successfully marked and dove the shallower wrecks like the Landing craft, the PBM Mariner, the Louie and the Scout you have no business trying mark and dive The Dawn or the Hauler or the Valiant on nitrox. You will be narced out of your mind at 115ft in sheet vis and either stressed or clueless. The south end vis is especially crappy due to the Cedar River. And you'll quite possibly trash the wreck(s). The Valiant in particular should never be dove from a boat again. It's easy to dive from shore with a scooter and that eliminates the risk of accidental shot destruction. It's the consistency of wet cardboard so don't even one finger touch that one.

 

[rick00001967]

Vis in the Great Lakes is 100x Lake Washington, its 8ft on a great day. 5-6ft on average, less where your shot impacts the silt.


Which are you thinking of here? MANY divers have missed the wreck and end up in a silt bomb in the bottom. Have you done any diving in Lake WA before? Which wrecks?

'Cause this is NOT how to dive Lake WA. We never just drop shots on any Lake WA wreck. This is how they get hammered and trashed. Punching holes in the fabric of the planes, breaking off wood from the boats. You need to be setting a shot line near but NOT on the wreck. Some of them are incredibly fragile. Then using a spool and a compass to connect the shot to the wreck.

Honestly if you haven't successfully marked and dove the shallower wrecks like the Landing craft, the PBM Mariner, the Louie and the Scout you have no business trying mark and dive The Dawn or the Hauler or the Valiant on nitrox. You will be narced out of your mind at 115ft is sheet vis and either stressed or clueless. The south end vis is especially crappy due to the Cedar River. And you'll quite possibly trash the wreck(s). The Valiant in particular should never be dove from a boat again. It's easy to dive from shore with a scooter and that eliminates the risk of accidental shot destruction.

so we now have a responsible post from someone who seems to have advanced local knowledge. hopefully the op will consider this advise

 

[rick00001967]

Why because if you don't know; don't ask?

It is a dive to recreational depths, and this is the advanced scuba section. If anything, someone my throw down a red flag when the OP casually mentions deco (for a few minutes), but I interpreted that more as a contingency in the dive plan, rather than the actual plan.

Knowing how to deal with accidental, or unplanned deco for a few minutes should be within the recreational discussion, as long as it is not planned, right? Or is it the diving over 100 feet on air, not something that should be discussed?

sorry. i mean no offense to the op. but it is clear they have no advanced training whatsoever. and although i do support peoples desire to advance their knowledge in the sport, these questions seem a bit too specific for my taste.
it is one thing to ask a general question about how tables work, or what the pros and cons are when using nitrox for example, in order to gain some understanding before taking a proper class.
but it is another ball game when a newer diver starts asking specific questions regarding specific dive sites and about the allowable bottom time, which gas to use, how much deco is acceptable etc.
do you want to be the one who provides all the answers and then read about a diving accident 6 months from now?
i am not suggesting this diver is planning to do that, but they might. and so might someone else who reads this thread.

 

[rhwestfall]

'Cause this is NOT how to dive Lake WA. We never just drop shots on any Lake WA wreck. This is how they get hammered and trashed. Punching holes in the fabric of the planes, breaking off wood from the boats. You need to be setting a shot line near but NOT on the wreck. Some of them are incredibly fragile. Then using a spool and a compass to connect the shot to the wreck.

Nobody puts mooring blocks in at valuable dive sites?