Which doubles?

[elan]

Thanks. As stated in the original post, I'm 6'/180 lb.

I figured that Tech 2 might well require something like HP130s (or my LP112s) for gas, which is why I wrote that this set of doubles only need to be suitable for Tech 1/1+.

The problem is that they require a _whole lot_ of lead to dive locally; even with my S/S BP I'd need another 12-14 lb. of lead, which makes the total weight far heavier than comparable steel doubles, and more than I want to use. I don't know of any local tech diver who uses Al80s, and I was ecstatic when I switched to steel tanks for my recreational diving; with my Asahi HP100s I dropped 9 lb. while gaining ~30% more gas. The Al80s do come in handy down the road for stage bottles so they aren't totally useless, but around here they don't make a lot of sense for doubles other than being inexpensive.

Guy

Sorry I missed your height in all the long post yeah forget about HP100. I have trouble trimming them even with the bands all the way up and once I sling the stages it becomes even worse. . They are short. And they do not give you opportunity to put extra weight without being overweight. Faber LP85s are longer as you saw and you can put weight on the tail. I have a set of LP85s but I need to trim them, not having time now ....

Here a lot of people from Fundamentals to Tech2 use AL80s (we have 36F in winter and 40-45 in the summer in most places at depth). My instructor told me you can use them up to Tech 1 level. Then alas, 130 or 104/112. I need 14 extra pounds with steel plate on them but boy they trim so much better. A big + with them as well as we can drive to Florida with those tanks and use them in warmer waters.

In your situation the best way to go I think will be to buy 2 Luxfers AL80 and double them up. When you move up your training ladder you break them down and have 2 good stages. And given you have to put the extra weight you can trim them for sure. They use standard size bands and standard manifold so you can always reuse them later so this is the no risk path for you. Meanwhile what you have is a working set of doubles with no trim problems and you will have time to look around and try other tanks. If I was starting the doubles road again I would go this way.

Out of 4 sets we have now I love the LP72s and AL80s, they both require extra weight.


P.S. I was just like you when I was thinking AL80 make no sense for our cold diving. But after fighting with trimming different tanks they started making way more sense.

 

[Guy Alcala]

Summarizing the trim comments of people about my height (6'), to date:

I'm 6'1" and use Worthington LP85's and they're great.

I am happy with my Worthington X7-100's . <snip> FWIW I am 5'11 and about 165lbs.

[6'2"?] Guy, I use both doubled Faber LP85's, and, doubled X7-100's. They are pretty indistinguishable, although if pressed, I'd put the Worthingtons as placing the weight a smidge more toward the shoulders.

Either way you can't go wrong. The Fabers are a bit easier to PP blend on top of leftovers; the extra volume of the 100's is nice to have for 18/45.

What is your height? If you are anywhere close to 6ft I would avoid all those tanks except Faber LP85 As the rest are shorter. I'm 6ft and I have troubles with the HP100s I can trim them with 4lb trim weight but it's not the best choice.

So, we've got one person around 6' saying they have no trim problems with Worthington LP85s, one who has no issues with the X7, one taller than me who likes both the X7s and Fabers, and one who likes the Fabers and votes against anything shorter, recommending Al80s as a reasonable, cheap alternative.

Well that's clear as mud, but the majority view (with one strong dissent) is that most people my height can trim out three of the four tanks I listed, well. My dive buddy has PSTs so I hope to borrow them at some point and give them a try, but at the moment it seems like I'm unlikely to go badly wrong with any of them.

Guy

 

[Adobo]

Instead of looking for something resembling a consensus, what if you were to consider which tanks give you the most chance of success?

Most divers who transition to doubles have to adjust for the doubles's tendency to be head heavy. There is a fair chance that you might have to make similar adjustments. X7s are the shortest, most negative tanks in your steel tank list. In other words, most limited options regarding how you can trim them out. Faber LP-85s are the longest, most buoyant tanks in your list. In other words, most flexibility in how you can trim them out. Worthington LP-85s and PST E7s are about half way in between.

The "land weight" of all of these steel tanks + required ballast will all be roughly equivalent. Double Al80s give you the most options for trimming out as they are really long and positively buoyant when empty. However, there is a steep penalty in land weight with double Al80s when used in temparate salt water diving. The only person I know who uses double Al80s on a regular basis for MoCal ocean diving is a strapping fellow who doesn't look much older than 30 years of age. Put a different way, I think he and his you back can take it. The same probably can't be said for all of us.

HTH

 

[Guy Alcala]

Instead of looking for something resembling a consensus, what if you were to consider which tanks give you the most chance of success?

Most divers who transition to doubles have to adjust for the doubles's tendency to be head heavy. There is a fair chance that you might have to make similar adjustments. X7s are the shortest, most negative tanks in your steel tank list. In other words, most limited options regarding how you can trim them out. Faber LP-85s are the longest, most buoyant tanks in your list. In other words, most flexibility in how you can trim them out. Worthington LP-85s and PST E7s are about half way in between.

Pretty much my thinking. If I could find a set of used E7s or Faber 85s, I'd jump on them. Actually, If I can find a good deal on any of these tanks I'd probably snap them up. My main concern was to make sure that there were no well-known deal-killer issues with one or more of them, and there don't seem to be. All are acceptable, and each have their good and bad points.

The "land weight" of all of these steel tanks + required ballast will all be roughly equivalent. Double Al80s give you the most options for trimming out as they are really long and positively buoyant when empty. However, there is a steep penalty in land weight with double Al80s when used in temparate salt water diving. The only person I know who uses double Al80s on a regular basis for MoCal ocean diving is a strapping fellow who doesn't look much older than 30 years of age. Put a different way, I think he and his you back can take it. The same probably can't be said for all of us.

HTH

I'm used to backpacking and my back can take it, but I see no reason to load myself up with weight and risk blowing out an ankle, when there's a better option. And then there's climbing a boat ladder. If I were in SoCal I think the Al80s would be a more reasonable option, but not up here, where I'll be doing the majority of my diving.

Thanks,

Guy

 

[elan]

Another couple of moments I forgot to mention are:

With those 24" tanks like HP100 it is a pain to don them when they are standing on a bench of the boat or any other bench. As they are short you have to sit down a lot and I cannot actually sit with them donned on a bench, they do not touch the bench when I sit normally so the bench will not support them and they are putting all the stress on the back. Another problem I have (but that is probably the problem with my wing DSS49 only) is that if you do not look after the bottom of the wing the wing tends to bend under the tanks and when you place the tanks on something they tent to sit on the wing chewing the bottom of the wing. If you have a shorter wing you might be ok. I do not have any of these problems with Faber LP85, Lp72 or AL80.

 

[Guy Alcala]

Another couple of moments I forgot to mention are:

With those 24" tanks like HP100 it is a pain to don them when they are standing on a bench of the boat or any other bench. As they are short you have to sit down a lot and I cannot actually sit with them donned on a bench, they do not touch the bench when I sit normally so the bench will not support them and they are putting all the stress on the back.

I have similar issues with my Asahis as singles (although they're taller than the PSTs/Worthingtons) but manage to slide in from below, i.e. my butt's not on the bench at the start. I'll have to ask Fofo how he manages with his PSTs once he doubles them, although he's a couple of inches shorter than me.

Another problem I have (but that is probably the problem with my wing DSS49 only) is that if you do not look after the bottom of the wing the wing tends to bend under the tanks and when you place the tanks on something they tent to sit on the wing chewing the bottom of the wing. If you have a shorter wing you might be ok. I do not have any of these problems with Faber LP85, Lp72 or AL80.

Good to know, as the DSS Torus 42 and 49 are on my short list of wings.

Guy