Sidemount Diving Book

[Peter Guy]

Rob -- congratulations and I'll probably buy one too.

Although off topic, a poster wrote: "Less buoyancy swing" when discussing differences twixt steel and aluminum tanks. Please, will someone explain to me how breathing 5 (or 6 or 10) pounds of air out of a steel tank results in "less buoyancy swing" than breathing 5 (or 6 or 10) pounds of air out of an aluminum tank?

Of course I know that your standard AL80 goes from slightly negative to slightly positive, but the swing is the same as a steel tank that goes from really negative to slightly negative -- is it not?

 

[rongoodman]

I'll be looking forward to seeing it too.

 

[bamafan]

Rob -- congratulations and I'll probably buy one too.

Although off topic, a poster wrote: "Less buoyancy swing" when discussing differences twixt steel and aluminum tanks. Please, will someone explain to me how breathing 5 (or 6 or 10) pounds of air out of a steel tank results in "less buoyancy swing" than breathing 5 (or 6 or 10) pounds of air out of an aluminum tank?

Of course I know that your standard AL80 goes from slightly negative to slightly positive, but the swing is the same as a steel tank that goes from really negative to slightly negative -- is it not?

This statement and the "balanced rig" statement some make have always never made sense to me. Air / gas weighs the same per cuft whether it is coming out of an aluminum tank or steel tank. The way I see it is that steel tanks cut down on the ballast you need to put on your bc. Either way you are going to be way over wheighted at the beginning of the dive or terribly light at the end of the dive. You must compensate for the ballast weight lost during the dive somehow. When you start diving large steel tanks and multiple stages this really becomes an issue because the gas volume used is so large. I like to think of it as more of where the majority of the ballast is carried.

 

[nakatomi]

I´am about to buy my first tanks, but I am unsure what kind I should choose for cold water diving in dry suit? Aluminium or steel?

There are some very opposing opinions when it comes to the choice of tanks.
Some people will claim that sidemount is always best when using aluminum tanks. The theory behind this claim is that the more neutral aluminum tanks "may" enable you to trim out easier or more naturally.
My experience is not so. I've used about 8-10 different types of tanks in cold water, ranging from 8.5l tanks (roughly LP50) to 19l (LP120) tanks, including several HP steel versions and different aluminum tanks. And they all let me trim out fine, some of them requiring trim weights, others not.

Depending on your setup, you can trim out perfectly with pretty much all steel tanks and of course with aluminum tanks too.
The huge benefit with steel tanks is, in general you will require much less weight when using them in cold water in a drysuit.
To me it makes a tremendous difference whether I wear 6kg (13lbs) or 10Kg+ (22lbs) of weights on my rig. That's the reason I own 5 sets of steel tanks for sidemount diving and use the aluminum 80s as stage tanks only.

---------- Post added September 26th, 2015 at 07:43 PM ----------

Of course I know that your standard AL80 goes from slightly negative to slightly positive, but the swing is the same as a steel tank that goes from really negative to slightly negative -- is it not?

That probably depends on the size of the tank and the initial pressure.
If you take two cave filled LP120 tanks with 3600+psi and breathe them down to thirds (or 500psi) your buoyancy swing will be more significant than breathing two aluminum 80s down to thirds/500psi

So assuming the same amount of gas is breathed, as in the exact same dive profile and duration, the buoyancy swing will be exactly the same, regardless the material and size of the tanks.

 

[Dive-aholic]

I would like a copy too!

Perhaps I can ask a fast question because I can not wait to buy my own gear for sidemount:
I´am about to buy my first tanks, but I am unsure what kind I should choose for cold water diving in dry suit? Aluminium or steel?

The answer...It depends. My suggestion...Put it off another week or so. I address that very question in my book. Don't waste your money on cylinders that may not work for you. There are too many variables to answer that question just based on cold water in a dry suit. Divers all over the world dive steel and aluminum cylinders in cold water with a dry suit. The question is not which cylinders are better but rather which cylinders you will need for your diving.

---------- Post added September 26th, 2015 at 01:33 PM ----------

Rob -- congratulations and I'll probably buy one too.

Although off topic, a poster wrote: "Less buoyancy swing" when discussing differences twixt steel and aluminum tanks. Please, will someone explain to me how breathing 5 (or 6 or 10) pounds of air out of a steel tank results in "less buoyancy swing" than breathing 5 (or 6 or 10) pounds of air out of an aluminum tank?

Of course I know that your standard AL80 goes from slightly negative to slightly positive, but the swing is the same as a steel tank that goes from really negative to slightly negative -- is it not?

Eric/bamafan did a pretty good job answering this. All else being equal, meaning gas volume, the swing will be the same. So whether you dive 3 AL80s or 2 LP85s, you will have the same change in buoyancy when you breathe those down. However, as you stated, AL80s will get positive while most steel cylinders will not. I say most because there are steel cylinders that do get positive as you breathe them down. In this case you still need ballast to remain neutral at the end of the dive with near empty cylinders.

 

[whitefang21]

i will buy one

 

[infamy]

Seem it is posted for sale on DGX already! Before even on your own site... Maybe they beat you to the punch!

https://www.divegearexpress.com/sidemount-diving-the-almost-comprehensive-guide

 

[stuartv]

The book will be available soon. I'm taking pre-orders now.

I want one. Does this post constitute a pre-order, or will you be posting more info on how to do that?

 

[catone]

I'll get one, too.

 

[sethw]

I would like one too please