AL80 Doubles Questions

[Divetech99]

I currently use 6 lbs weight on an AL80 singles DIR rig. Current singles rig is: Halcyon Infinity AL Backplate BCD, it came with a STA and metal camband buckles, Apeks XTX200 on a long hose, bungeed backup second stag, DIN Apeks FSR first stage with a yoke adapter. Wetsuit 3mm. OMS fins. Questions:

1. On a Doubles AL80 setup, will I still need to add weights? Planning to still use the Halcyon Infinity AL Backplate BCD and replace the wing with an Oxycheq doubles wing (40-45 lbs lift). 3mm wetsuit with 1mm hooded vest. I'm estimating that the weight of the manifold and tank bands will offset the need for additional weights.

2. Planning to use my existing Apeks FSR on right post and get an inexpensive Apeks DS4 for the left post. Does this make sense? Am I better off just getting 2 DS4's? Trying to avoid new expenses but willing to do what's best.

3. My existing hose lengths all conform to the standard DIR rig for singles. I plan to use the same hoses for doubles. Do I need to change any of the hose lengths in a doubles configuration? My LPI hose is just the right length for the short BCD hose of the Halcyon Infinity on a singles setup. I'm concerned that the hose may be too short for Doubles since it's going to be coming off the right post.

Thanks for any help.

 

[sunchaser73]

Is this doubles rig for ocean diving? What are you using for redundant buoyancy control? You should consider either a dual bladder wing OR a dry suit so that you have back-up buoyancy control.
For the regulators, my opinion is to have identical first and second stages. I don't recall if it is a "requirement" but it makes sense to have matching regulators - that way everything breathes the same.
You will most likely need to get longer inflator hoses for your doubles rig.
To determine the need for additional weighting, you'll need to know the total weight of your doubles rig, and look at the buoyancy change in your twin AL-80s over the course of a dive. Prior to conducting an open water dive, your best bet is to check your weighting in a pool, and then calculate the additional weight based on the difference between fresh water and salt water. On your first ocean dive in doubles, it would be ok if you are slightly overweighted, so long as your wing can overcome it.
As with any configuration change, you'll need a few dives to fine tune everything.
Hope this helps. Safe diving!


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[currier]

It would surprise me if you required any additional weight given the wetsuit(s) you listed as wearing, but some of us are fatter than others, and let‘s face it, we all float differently. The buoyant shift on two aluminum tanks could be enough to upset your ease at a shallow stop if your pressure was low. Bleed ‘em out and check yourself before a “real“ dive to be sure. Don‘t forget reels, lights, etc. that you would otherwise carry, too - all that stuff adds up.

Your LPI hose likely needs to be swapped out, there is more of a gap you‘ve got to cover between a right post vs. a center valve on a single tank, but it also depends a lot on the length of the corrugated hose on the new wing.

My opinion on your reg situation makes little difference. Buy what you can afford, a DS4 will never let you down. I got lucky and scored nice sets of used ATX200 a few years ago for the price of one DS4/50 new.

Have fun in your new setup, but take the time to practice and ingrain those valve drills into memory.

 

[decompression]

Are you DIR trained? You should know, either by training or by google how to calculate a balanced rig. We can only offer estimates of your rig for weighting. And I would say you're close with adding another Al 80 but balanced by bands/manifold etc.

I strive to use identical stages, tech is no time to go cheap.

Yes, you'll probably have to change some hoses. Set everything up get it as streamlined as possible.

Accessories (lights, reels etc) are not part of your rig calculation but are accounted for in your lift calculation.

Do your weight checks and see how it works. Best of luck.


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[Kevrumbo]

I currently use 6 lbs weight on an AL80 singles DIR rig. Current singles rig is: Halcyon Infinity AL Backplate BCD, it came with a STA and metal camband buckles, Apeks XTX200 on a long hose, bungeed backup second stag, DIN Apeks FSR first stage with a yoke adapter. Wetsuit 3mm. OMS fins. Questions:

1. On a Doubles AL80 setup, will I still need to add weights? Planning to still use the Halcyon Infinity AL Backplate BCD and replace the wing with an Oxycheq doubles wing (40-45 lbs lift). 3mm wetsuit with 1mm hooded vest. I'm estimating that the weight of the manifold and tank bands will offset the need for additional weights.

2. Planning to use my existing Apeks FSR on right post and get an inexpensive Apeks DS4 for the left post. Does this make sense? Am I better off just getting 2 DS4's? Trying to avoid new expenses but willing to do what's best.

3. My existing hose lengths all conform to the standard DIR rig for singles. I plan to use the same hoses for doubles. Do I need to change any of the hose lengths in a doubles configuration? My LPI hose is just the right length for the short BCD hose of the Halcyon Infinity on a singles setup. I'm concerned that the hose may be too short for Doubles since it's going to be coming off the right post.

Thanks for any help.

I'm 5'7" at 155lbs and use 26lbs of weight for a single AL80 tank with a drysuit in temperate Southern California ocean waters: 6lbs SS BP with 20lbs weight belt, no STA, and heavy rubber jet fins to counter floaty drysuit legs & feet. Buoyancy Wing is an old Halcyon Pioneer 32.

My double AL80's are Catalina's and I use 17 to 19lbs total: 6lbs SS BP; 2 x 2lbs bullet weights in the "V" space between the tanks; a 5lbs tail weight and 2 to 4lbs in a small front weight pouch near my BP belt buckle, with drysuit & jet fins. Wing is a Halcyon Explorer 40.

In tropical warm water with a 0.5 mil skinsuit & 3 mil hooded vest, no added lead weight with single AL80 and 2lbs AL BP, no STA, with lighter jet sport plastic fins. But with double Luxfer AL80's & 2lbs AL BP, I need 6lbs in a weight pouch between my shoulder blades to level out horizontal trim, and prevent upper torso from pivoting up (with resultant knees rotating down into the silt) when taking a breath.

Here's a drawing for mixing and matching Apeks 1st stage setups & hose routing:

http://www.scubaboard.com/forums/attachment.php?attachmentid=104657&d=

 

[decompression]

Good pic, Kev.

Wish it showed the other hoses (drysuit).


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[Kevrumbo]

Good pic, Kev.

Wish it showed the other hoses (drysuit).


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Yeah . . . Drysuit hose routing & length running from the Backgas Left Post instead involves some trial & error custom fitting and personal preference unlike using a standard separate 6cf inflation bottle, reg and shorter "less loopy" hose.

 

[halocline]

1. On a Doubles AL80 setup, will I still need to add weights? Planning to still use the Halcyon Infinity AL Backplate BCD and replace the wing with an Oxycheq doubles wing (40-45 lbs lift). 3mm wetsuit with 1mm hooded vest. I'm estimating that the weight of the manifold and tank bands will offset the need for additional weights.

2. Planning to use my existing Apeks FSR on right post and get an inexpensive Apeks DS4 for the left post. Does this make sense? Am I better off just getting 2 DS4's? Trying to avoid new expenses but willing to do what's best.

3. My existing hose lengths all conform to the standard DIR rig for singles. I plan to use the same hoses for doubles. Do I need to change any of the hose lengths in a doubles configuration? My LPI hose is just the right length for the short BCD hose of the Halcyon Infinity on a singles setup. I'm concerned that the hose may be too short for Doubles since it's going to be coming off the right post.

Thanks for any help.

1. I find that my ballast needs for a single AL80 and double AL80s are roughly the same, given the same wetsuit. So I don't think you'll need to add weight, but you really need to do a weight check. You might end up using a bit less weight. You have an additional 4 lbs of positive buoyancy from the extra tank, but the bands and manifold, and extra 1st stage together are usually more than 4 lbs negative.

2. I don't really know much about the particular 1st stages you're talking about, but there is no reason to have "matched" 1st stages. They just have to both be decent quality and allow for the hose routing you want.

3. The alternate 2nd stage hose will be coming from the left, so I use a slightly longer (24") hose for that than I do on single tank, but you may be fine with yours. The LP inflator hose you'll just have to try, the big issue is with the length of the corrugated hose.

 

[Divetech99]

In tropical warm water with a 0.5 mil skinsuit & 3 mil hooded vest, no added lead weight with single AL80 and 2lbs AL BP, no STA, with lighter jet sport plastic fins. But with double Luxfer AL80's & 2lbs AL BP, I need 6lbs in a weight pouch between my shoulder blades to level out horizontal trim, and prevent upper torso from pivoting up (with resultant knees rotating down into the silt) when taking a breath.

Kev, thanks. Appreciate the photo and inputs. Question, I would assume that with double AL80s, you'd be head heavy due to the manifold and regs. Wouldn't tail weights be the trimming factor to be horizontal?

 

[tomfcrist]

Question, I would assume that with double AL80s, you'd be head heavy due to the manifold and regs. Wouldn't tail weights be the trimming factor to be horizontal?

It could be. If you wear heavy fins you may not need tail weight. If I'm diving al80's and a 3mm, I just stuff a 2lb soft lead bag in between the plate and the wing...where you put it will change your CG in the same way a tail weight would.