Question LP85 vs HP100 for cold water singles rec diving

[mnash760]

I know the LP85 vs HP100 question has been discussed at length but most of the ones i have found have been doubles or mixed use in cold and warm waters. I will be using this tank to dive exclusively in cold water with a 9/7/6 Semi dry year round for single tank rec dives. It seems to me based on the buoyancy charts that an HP100 or even an HP80 would be the better choice as it's more negatively buoyant. I also have my own fill station so short fills are not an issue, and if i take it on a boat it still holds more gas than an 85 even short filled. I know alot of people love the LP85 however, so I was looking to see if there was something I am missing here, or if there are other tanks you guys would recommend as well. Thanks!

Both options are assuming newer faber tanks as well

 

[Rilelen]

I love LP85s, assuming you can cave fill them (which, sounds like you can). A cave-filled LP85 holds as much if not more gas than an HP100.

If you can try diving both, I’d recommend it - they feel different. I was surprised I liked the LP85s so much more than the HP100.

 

[Marie13]

HP80s are great single tank for short people. I’m 5’5” and they worked well. For taller people, they look like a soup can on the back!

 

[RyanT]

Given that you're diving a thick wetsuit, the heavier buoyancy of the HP100 will serve you well.

 

[inquis]

The apparent buoyancy difference between HP100 and LP85 is an illusion. While the HP is specced at -0.6 lb, it also weighs 34 lbs. If you take a LP85 (31.2 lb dry and +2.3 lb wet) and 3 lb of lead (2.7 lb wet), that will also weigh 34 lb dry. Wet it will be -0.4 lb. Not really worth worrying about a 0.2 lb buoyancy difference.

If the boat's tank rack is the type with two arms, you'll appreciate the slightly narrower LP85 that will slide so easily into its grasp.

If filling is not an issue, I believe the LP85 is the better choice. Do not get the HP80 unless you're about 5'3 or shorter.

 

[Eric Sedletzky]

Get the 100.
No such thing as too much air.

 

[tmassey]

The apparent buoyancy difference between HP100 and LP85 is an illusion.

This is something that drives me nuts. People ask something like, “how much lead can I drop when I use an HP 120 instead of an HP 100?” The answer? “*Add* two pounds. “But the tank weighs 12 pounds more! Surely I can *drop *some lead…” Nope. (Ref for PST E100 vs E120)

So, to answer the original poster’s question: cold or warm, wet or dry…. The difference between any given steel tanks makes almost no difference in buoyancy. Like @inquis notes, what differences there are can be addressed with a single tiny weight in a trim pocket on a cam band — if at all.

So how should you decide? All the other characteristics that make tanks unique: length, diameter, dry weight and capacity. If you have back trouble and are doing simple recreational dives, then use the lightest tanks you can that give you the air capacity for the dive length you want. Work out regularly and you’re doing a more challenging dive? Dive the biggest tank that you can move around reasonably. Is flow an issue? Long, skinny tanks are more streamlined. Live in a place where filling LP tanks beyond rated pressure is impractical? Then as much as I love them, I would stay away from low pressure tanks.

For me personally, I would choose the LP 85s over the HP 100, pretty much without exception. But that’s because I am tall with a long torso, and the LP 85s fit better than the HP 100s. I also own my own compressor, so I do not need to worry about how other people will fill them. If any of those factors were not true, it’s unlikely the LP 85 would be my first choice.

Tanks can be a somewhat personal choice, and unfortunately most of the factors that will determine whether the tanks will work best for you or not cannot be found on a tank spec sheet. your physical dimensions, fitness and the details of your style of diving all make a difference.

 

[MrVegas]

I dive LP85 doubles and really like them. However, for single tank diving, I might pick the HP100. Other than what people have already said, the HP100 is 7.25 inches -- same as an AL80, so you probably don't have to adjust your tank strap on your BC if you go on vacation.

 

[mnash760]

Thanks for all the input, it looks like I’ll have both that I can borrow for some dives coming up so I can really see how they feel in the water.

 

[happy-diver]

The one that holds more air weighs substantially more with a cave fill