Yet another tank Q?

RDRINK25 · Jul 21, 2011

OK I am in the market for tanks for my wife and I. We do all recreational diving some saltwater in the gulf or maybe some freshwater springs or quarries. My wife is 5'0" and 120lbs and I am 5'10" 200 when we go to saltwater using a al80 my wife uses about 10lbs of lead I use about 8 with a HP100 if I have to use an al80 im about 15lbs. I am looking for tanks for us to have and use when needed I use more air than her and why I opt for the 100. She has used a HP100 and thinks it is heavy but is ok with the al80. I recently went lake diving and with a 5mm wetsuit using a hp100 with 500 psi in the tank on my safety stop I took out my weights and I still sunk. I am concerned on not having any ditchable weight or should I? I have seen these new al80's that are neutral and negative with 500psi and they sound appealing. Just looking for some advice on getting 2 tanks for me and 2 for her. They all don't have to be the same also what about an al100 why doesn't any use them? Thx in advance.

markr · Jul 22, 2011

Here is a link to some tank stats that may be helpful Scuba Cylinder Specification Chart from Huron Scuba, Ann Arbor Michigan

You said your wife finds the HP100 heavy but if you look at the specs its only about one to two pounds heavier then an AL80. It has the added benefit of staying negatively buoyant when empty so she should be able to take a couple pounds of lead off to offset the extra weight of the tank. If she really wants a lighter tank you could try an HP80 which is four pounds lighter then an AL80 and is shorter which may be an advantage for someone that's 5'0".

sam1 · Jul 22, 2011

RDRINK25:
I am concerned on not having any ditchable weight or should I?

You need to be able to swim up (comfortably) in the event of a failure of your BC or wing when you are most negative, which, in a wetsuit, is at depth (neoprene compression) with a full tank. This may or may not require ditchable weight.

A bit of an elaboration on markr's post. Besides being (approximately) four pounds lighter than an AL80, an HP80 is 6+ pounds less buoyant when empty (-2.5 vs +4) which means that much less lead is needed. The weight difference and the buoyancy difference means ten fewer pounds to carry around.

OldNSalty · Jul 22, 2011

Sounds like an HP80 is perfect for your wife.

As for an AL100-people do use them. I have 2 and dive them all the time. I like them (but I am thinking of going to an HP100).

If you want to swap your steel for Al I will trade you

Onewolf · Jul 22, 2011

sam1:
...snip...

A bit of an elaboration on markr's post. Besides being (approximately) four pounds lighter than an AL80, an HP80 is 6+ pounds less buoyant when empty (-2.5 vs +4) which means that much less lead is needed. The weight difference and the buoyancy difference means ten fewer pounds to carry around.

My wife has HP steel 80s for this reason. She was able to carry ~8 lbs less weight with the HP80 tanks versus the AL80.

I bought HP 100s and 117 tanks for: more air, more negative.

Akimbo · Jul 22, 2011

A 5' female can often get about the same bottom time out of a single 65-72 as a 5'10" male can get out of a 100 Ft³ cylinder. An Aluminum 80 is quite long for a 5' female, especially sitting on a dive boat bench.

For example, Aluminum 80s are about 25" tall without valve where the Worthington X-65 is 16.7" and the X7-80 is 19.8".

RDRINK25 · Jul 22, 2011

thx I think the HP65 will do only I dont know if it will fit her bc. She has a Mares Aikailla and may not fit I think the HP80's will be close. There is 2 tank straps on the bc.

Akimbo · Jul 22, 2011

RDRINK25:
thx I think the HP65 will do only I dont know if it will fit her bc. She has a Mares Aikailla and may not fit I think the HP80's will be close. There is 2 tank straps on the bc.

I would be very surprised if there is a problem. Lots of dive shops have a few 65s or rent and training. If not, you can make sure by attaching her BC as high as possible and a steel 7¼ diameter cylinder (top of top band at the top of the cylindrical section). Measure the height of that cylinder. As long as you measure more than the difference in cylinder heights between the lower strap and top of the boot you are golden. Hope that makes sense.

elan · Jul 22, 2011

I would skip on hp80 for her for the very simple reason. She might not have adequate supply for you to bail out. If you dive to 100 ft with her your rock bottom will be about 40 cuf. Which only leaves 40 cuf for her. And thats in an ideal situation when the pressure in the water is 3442 which I personally never saw in HP tanks in the water. Even in this ideal case if you spend 20 mins at at the bottom her rate must be .5 which is doable for a female but remember it is an ideal case.
If you dive nitrox the rate should even be better to use the whole potential.

If you carry a pony then it would give her more gas but you need the pony

Hp100 would weight 2 lb less than al 80 on land and still would have 22 cuf more gas than al80. For her height it should be good to.

markr · Jul 23, 2011

RDRINK25:
thx I think the HP65 will do only I dont know if it will fit her bc. She has a Mares Aikailla and may not fit I think the HP80's will be close. There is 2 tank straps on the bc.

One other thing to consider with a short tank and a BC with two straps is steel tanks have a boot on the bottom because the tanks have rounded bottoms. This may cause a problem with the bottom strap. Of course with a tank as short as a HP65 you may not need the bottom strap.

Yet another tank Q?

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