Worthington tanks, weighting etc

[Scott M]

Kind of late to ask now but........In an effort to put more none ditchable weight on my back for D.S. diving I have decided to relagate my AL80's to wet suit divng only. Which brings me to steel tanks, after some research into them and talking to few locals I have decided on the Wothington HP100's as my tank of choice and got a great deal on a few new ones. Did I make the right choice? Good tanks? I have read a lot of good and could not find anything bad about them.

The HP100's are -10 fulland -2.5empty, my AL80's (catalina) -1.6 and +4.1. I assume the only bouyancy that matters would be the ending weight, is this correct? If this is the case the steels should allow my to drop 6.6 lbs of ditchable weight. yes/no?

One other quick question regarding weight. Right now with very light undergarments I am carrying 24lbs of weight (12 and 12) I am a little heavy but since I am new to D.S. I don't mind being slightly heavy until I am more comfortbale. When I switch to heavier undergarments say to something like the White's MK2's and then more as the water gets colder. Is there a rule of thumb on how much extra weight I will need?

Regards

 

[Wayward Son]

Yes, the tanks will let you take 4 to 6 lbs off your belt. assuming the weights you got from the tables are correct, you should be able to drop 6. You might want to weigh them both to see for sure.

 

[Scott M]

Yes, the tanks will let you take 4 to 6 lbs off your belt. assuming the weights you got from the tables are correct, you should be able to drop 6. You might want to weigh them both to see for sure.

Great idea, I have read many of the tables are incorrect or tabulated differently. It would make more sense if they all used the same standards and I would prefer to see the weight with 500lbs since I never run under that.

Thanks

 

[Wayward Son]

I have a PST E7-100 and now a Faber X7-100, both are close in weights. When I have them both here at the house together I need to weigh them & see just how close. They're not as heavy as yours, I can take about 4 lbs off with them compared to an AL80

 

[Scott M]

I have a PST E7-100 and now a Faber X7-100, both are close in weights. When I have them both here at the house together I need to weigh them & see just how close. They're not as heavy as yours, I can take about 4 lbs off with them compared to an AL80

Great info. thanks. Some friends of mine have the PST HP80's and really like them. I was thinking I have my trim pretty much spot on so I wanted the longer tank because I was afraid the shorter one would move too much weight up farther on my back and I didn't want that. Plus it never hurts to have a little extra gas when your diving with very experienced divers.

 

[Wayward Son]

I also prefer a longer tank. Doesn't matter at depth, but I find the short fat ones don't balance as well when I'm bobbing around the surface waiting for a boat.

 

[Leadking]

Yes, the tanks will let you take 4 to 6 lbs off your belt. assuming the weights you got from the tables are correct, you should be able to drop 6. You might want to weigh them both to see for sure.

Weighing tanks on land will not work. It is the displacement of the cylinder along with the weight that determines buoyancy.

 

[Scott M]

Weighing tanks on land will not work. It is the displacement of the cylinder along with the weight that determines buoyancy.

With that in mind, How does someone do the math to determine a starting point when switching to steels.

 

[Wayward Son]

This is true, but the land wt is provided. You can at least confirm that value.

Ultimately, you work it out the way you do all weighting. Make your best guess at a starting point, dive with that weight & see if you're still negative at the end of the dive (assuming you're down to 500 lbs or so). If you are, take off 2 lbs next time & do the same.

Or you can adjust weight until you're neutral at the surface with a full tank, then add enough lead to cover the bouyancy swing of the weight of the air for that size tank.

 

[Leadking]

With that in mind, How does someone do the math to determine a starting point when switching to steels.

That is a conundrum. There are charts available that list various buoyancy characteristics, but as a former distributor of cylinders, I will tell you that most are inaccurate due to the following:

1. with or without valve
2. salt or fresh water
3. full or empty
4. and lastly, some distributors just plain lie to give their cylinders favorable attributes

Use the charts as a guideline but not as gospel!

I wish you good diving.