Nitrox vs larger tank

[KeithG]

forgot to ask about bottom times. Are you trying to stretch a 30 minute dive to 35 minutes? Or are you whining about having to surface after 70 minutes?

 

[Steve_C]

i have dove with some obese divers who also happened to have a few thousand dives under their belts. They had very good SAC rates. Even a huge diver can bring their SAC rate down as they get comfortable in the water and learn to be relaxed and be economical with exertion.

You could get a different buddy.

Swim less and look more. A large diver, possibly a bit over weight, trying to keep up with another swimmer will suck a lot more air than if they are relaxed and doing less exertion.

If you are left with 1250 and they are left with 500 out of 3000 then if you want to get a longer dive they need a tank that is about 40% larger.

 

[T.C.]

His S.A.C. Is larger than mine

Just noticed this. Ah...scuba diving. The only sport where grown men will brag about how small their S.A.C is.

 

[scubadiver888]

Suggest your buddy take a Peak Performance Buoyancy course. Learning good buoyancy control will probably help his SAC rate the most.

Additionally, you dive AL80s and your buddy dives a larger tank. The one thing to watch out for however is if the heavy tank causes your dive buddy to get a little winded getting into the water, take a few moments to just relax and get his breaking back to normal.

Finally, how does his regulator breathe? If it is breathing hard, he might be fighting with it. This added effort might cause a higher SAC rate.

 

[maniago]

We have choice of either 100 cubic foot air tanks or 80 cubic foot nitrox tanks.

Ok hang on a sec. I just noticed this in your original post. Seems like you have your solution. You dive the 80s and he dives the 100s. Whats the problem?

 

[scubadiver888]

Ok hang on a sec. I just noticed this in your original post. Seems like you have your solution. You dive the 80s and he dives the 100s. Whats the problem?

Actually, as Steve_C points out, the buddy needs approximately 40% more air to match the original poster's air consumption. If he uses a 100 cu.ft. tank and the OP uses an AL80 (really 77.4 cu.ft.) then the buddy only has 29% more air. The buddy's SAC rate will still be the limiting factor.

 

[kelemvor]

Just noticed this. Ah...scuba diving. The only sport where grown men will brag about how small their S.A.C is.

Low, not small. Important distinction!

 

[maniago]

Actually, as Steve_C points out, the buddy needs approximately 40% more air to match the original poster's air consumption. If he uses a 100 cu.ft. tank and the OP uses an AL80 (really 77.4 cu.ft.) then the buddy only has 29% more air. The buddy's SAC rate will still be the limiting factor.

Horseshoes and handgrenades. They just need to get closer together in time so the OP can stop fretting over it - exact is not required. Moreover, if they have only a choice between 80s and 100s, nothing else moves them in the right direction easily.

 

[Candiru]

This is exactly how our debate went too. In reality we won't worry about it much when we start the trip with our goal being 60 min dive irregardless of depth needed to reach that goal. I'm sure that we'll both end up with nitrox 80's even though we would be better off with a 100 and 80 air. That was the key point of the debate. There is no getting around 10((weight in kg)^(3/4)). Plus the alum 100 are half the price of a nitrox 80.

 

[scubastingray]

Ok hang on a sec. I just noticed this in your original post. Seems like you have your solution. You dive the 80s and he dives the 100s. Whats the problem?

Right, so he shouldn't bother with nitrox in the 80 if his buddy is diving the 100 on air.