Calculating how much weight to leave behind with HP100

[HugoSolano]

I just purchased a Faber FX100 tank, and it states that it is 34.3 pounds and -8.41 lbs full in water and -0.59 lbs empty in water.

Now can anyone help me out in figuring out how many pounds I should leave behind from my belt to compensate.

I used to dive AL-80s and used 18 lbs to be fine and dandy. Now with the new tank i should think that there is a change. I just need to know the equation.

A typical AL-80 tank weighs around 34 lbs and is -1.5 lbs full in water and 4.4 lbs when empty.

I am sure someone has figured this out already, but I can't seem to wrap my head around it.

Thanks!

 

[RonFrank]

Drop 5lbs, and see how it goes. There is a good chance you are a bit overweighted anyway, but hard to say. 5lbs is the difference between the old tank, and new tank.

Start there, and if you feel solid holding shallow ascents, you can shave off some additional weight in the future.

 

[Scared Silly]

Basic math just subtract the difference.

HP100 -8.41 lbs full in water and -0.59 lbs when empty in water
AL 80 -1.5 lbs full in water and 4.4 lbs when empty in water

if one does the math there is a 5lbs difference which is what you can drop.

Edit fixed my typo

 

[cwkline]

Check your math. 4.4 - (-0.59) = 4.99 or 5 lbs. There is no need to weight something that is already negative.
Charlie

Basic math just subtract the difference.

HP100 -8.41 lbs full in water and -0.59 lbs when empty in water
AL 80 -1.5 lbs full in water and 4.4 lbs when empty in water

if one does the math there is a 6lbs difference which is what you can drop.

 

[NJMike]

As I understand it, you are concerned with the difference in weight at the end of the dive, hence the weight difference with the tanks empty.

So your AL80 is +4.4 lbs empty, the HP100 is - .5.

You will be 4.9 lbs heavier at the end of the dive at your safety stop. So you should be able to drop 5 lbs that you are now carrying.