The trouble with steel is...

[Coll]

I recently switched from an Al80 to a Steel HP 100. It feels more comfortable but I'm having trouble with my buoyancy. Has anybody else experienced this? It's most significant towards the end of the dive, obviously the steel is still negative at the end while an Al80 is pretty positive. Does anyone have any particular advice? Or is it just dive dive dive and it will come? Thanks all!

 

[widget]

I think its fairly normal to have a few bouyancy issues after a swop like that.

You probably find you are a bit on the heavy side now (lead weight that is ) so you could probably drop a few pounds on your weight belt, as a start point.

Best is to probably do a bouyancy test in a deepish pool or somewhere in a controlled enviroment where you can adjust your weight easily.

I like to be slightly negative and descend quickly, a puff or two of air in my BC and I am neutral - but thats just me, others may prefer differant.

 

[Gombessa]

Coll - have you adjusted your weights to account for the steel tank? Near empty, an AL80 will be about 4lb positively buoyant. An HP100 will be more than 1lb negatively buoyant.

What this means is, if you were correctly weighted with the AL80, you should be able to take about 5lb off of your weight belt or integrated weight pouches, when you switch to the HP100.

 

[Coll]

Hey folks, thanks for your responses. Yes I took five pounds off my belt, I think I may be able to remove one or two more, perhaps that would do the trick. I think I'll just have to go diving to get used to it, what a shame!

 

[spectrum]

You should need to drop 5-6 pounds depending on the brands in question.

The other varriable is cylinder balance. If you were diving Catalina AL80 s then you are accustomed to a bottom heavy cylinder. Luxfur AL80s may be more steel like in weight distribution.

I would not dive it and expect to adapt if you truly had a good configuration for trim before. With the right configuration adjustment the cylinder swap should be tranparent. I switch through 4 different cylinder types and each has it's own slight change in how much weight goes where but they all dive second nature in the water.

Pete

 

[halocline]

Another thing is that the gas in the cylinder weighs more (there's more of it) so you have a larger swing throughout the dive. In practical terms, you'll begin the dive with more air in your BC because you'll be compensating for the increased gas weight. More air in the BC means trickier buoyancy control.

You're also probably just not used to it yet, and you might not have your weight requirement dialed in perfectly.

 

[mpgunner]

Also check where the tank heigth is on your back. You may need to adjust a little (up or down) and that could make some difference.

 

[Charlie99]

I recently switched from an Al80 to a Steel HP 100. It feels more comfortable but I'm having trouble with my buoyancy. Has anybody else experienced this? It's most significant towards the end of the dive, obviously the steel is still negative at the end while an Al80 is pretty positive.

Could you be more specific about what sort of trouble you are having towards the end of your dive. Normally, the only problem that shows up near the end of the dive is being too buoyant due to not enough lead.

It doesn't matter that the AL80 is buoyant at the end of the dive and the HP100 is negative. What matters is that the AL80 will be 6 pounds lighter at the end of the dive and the HP100 will be about 7-1/2 pounds lighter.

Charlie Allen

p.s. The specs of the 3500psi and the 3442psi HP100 tanks differ slightly. Which manufacturer's tank do you have?