Retrofit At-Pac project

[jadairiii]

When the weather turns bad, and you have idle hands, well, your mind starts to wander….If any of you owned and dived an At-Pac for any length of time you will know it was a great piece of dive gear for it’s time. It had its flaws, but overall, way ahead of its time. I used one for close to 30 years until I switched to a BP/Wing. One of the things I loved about the At-Pac was the Fairings. I have two, they were the ultimate “cool”, although not real practical. That said, I got to thinking about how I could retrofit one so I could use my standard rig/backplate. Quick switch and I’m diving in style.

First, understand that the fairings could only be used with a steel 72 due to the geometry of the At-Pac so that was my first goal was to see if I could get an 80 to work. The opening at the bottom was just large enough. Second problem, larger yokes and yoke screws created a problem when using a fairing, you had to move the fairing up high enough so it could close (you see older ones with a telltale crack up high). And third, a doughnut wing would not work, I would need a horseshoe wing.

With that in mind, I used a Halcyon STA and mated it to one of my DIN 80’s. I then fabricated two brackets to hold the fairing between the STA and BP (cross brackets). Remember that the fairing laced on to the At-Pac. That worked but since my BP was now away from the fairing, that fairing was not stable. Easy fix was to make two rubber wedges between the BP and fairing. I also found a 40lb wing (Revo) that works better than the original At-Pac 60lb lift wing! I have to say, the result was better than expected. Tested it in the pool and works great. Next test will be a beach dive. Nice thing is now I can use my standard rig, everything in the same location…..and I look super cool!

 

[johndiver999]

I spend 3 hours making a lionfish hotel, and then loose two in 6 weeks. Idle hands, I guess. Now go cut the grass!

 

[jadairiii]

Update, first beach dive with my Frankenstein AtPac. It dives just as it did when I used it with the At-Pac, which is nice, but I get to us an alum 80. And when I say dives like the original set up, lots of drag in the water and on the surface.

But here is the "problem" of the updated system, if you look at old photos of divers diving an At-Pac, shell or no shell, the diver's trim was not horizonal, we were more in a 25 to 45 degree angle or vertical. With the BP/STA I was horizonal. In that position, the regulator exhaust goes directly into the shell, through the hose openings, so you get this odd "bump" feeling as the air hits the top of the shell and exhausts through the small top vents and bottom. But still super cool!

 

[JMBL]

Never heard of that rig on this side of the Atlantic. It's puzzling to me. Would please explain us what you like so much about, what are its pros and cons ? I'm sure, it'll be interesting to know.

 

[jadairiii]

Never heard of that rig on this side of the Atlantic. It's puzzling to me. Would please explain us what you like so much about, what are its pros and cons ? I'm sure, it'll be interesting to know.

Back in the early 70's the At-Pac was the original "back plate/wing" rig. At a time when the only "bc" was the horse collar or mae west vest , and very few had power inflators, the At-Pac came standard with a power inflator, and back inflation bc. Along with that, the backpack was hollow and the diver would add marbles (as filler) and lead shot (as weight) so all of your weight was carried on your back, center mass. Plus you could adjust where the weight was in the pack.

The Pros? WaterGill revolutionized buoyancy control. Here was a "system" (with or with out the shell) you could set up and everything you needed was in a "single package", like is standard today. You put it on your back and went diving, or dropped it in the water, swam on top of it to the dive site and then put it on in the water. Within 5 years of its release, virtually all manufacturers had back bc's, every bc had some sort of power inflation and jack bc's were coming out. Signaling the end of the horse collar bc. What divers take for granted today, was not even a consideration in 1972.

The cons, they had issues too, which also lead to their demise. Power inflator was finicky, it really was not a great system for double tanks, the weight system had issues and it did not "travel well", since you needed to empty the pack and then it didn't dive well empty. There were better backpacks by then. Also, the shape of the back pack put your tank farther away from your body which added to balance issues for some, especially with heavier tanks.

And that is sort of why the At-Pac is really not that well known to the "masses", WaterGill/Seapro stuck around into the 80's but so many other companies were producing the same thing, or better, the At-Pac drifted into obscurity.

Dont get me wrong, I used my At-Pac from 1977 into the 2000's and loved it. But doughnut wings, and SS or alum back plates are better, more robust. And most people preferred the "jacket style" bc.

The shell (or faring as it was called) was more of a gimmick, back in the 70's Jacques Cousteau was on tv and his divers were using gear housed in a "streamlined" shell, so WaterGill produced the shell. Scubapro, US Divers, Dacor, Technisub (and a few others) all followed suit and produced their own "streamlined" diving "system" soon there after but none lasted long. Bulky, hard to use on dive boats, lot of drag in the water, and other than the Dacor system, none of the others could be used with the new standard Alum 80. But they still look super cool!

So there is the history in a nut shell. For people that started diving in the 80's and beyond, all of this was pretty much in the review mirror. Let me know if you have any specific questions. Hope this helps.

 

[JMBL]

Dont get me wrong, I used my At-Pac from 1977 into the 2000's and loved it. But doughnut wings, and SS or alum back pThe shell (or faring as it was called) was more of a gimmick, back in the 70's Jacques Cousteau was on tv and his divers were using gear housed in a "streamlined" shell, so WaterGill produced the shell. Scubapro, US Divers, Dacor, Technisub (and a few others) all followed suit and produced their own "streamlined" diving "system" soon there after but none lasted long. Bulky, hard to use on dive boats, lot of drag in the water, and other than the Dacor system, none of the others could be used with the new standard Alum 80. But they still look super cool!

Thanks a ton for a very clear and detailed explanation. I remember seeing the Cousteau shells you've mentioned : I grew up in the 70's in front of a TV set, became a diver because of Cousteau. A common sickness around here I'm sure. Those shells did and still look cool today.

I've being wanting to get one for years. So far, could lay eyes only on 2 of them :

- 1st in the early 90's, was still a student and a beginner diver, I had limited funds and plenty of more pressing stuff to buy, so I let it pass,

- 2nd one, 2 or 3 years ago, prisitine condition, but the price was just plain silly, so I couldn't bother.

Maybe the 3rd one will be the right one.

 

[jadairiii]

Thanks a ton for a very clear and detailed explanation. I remember seeing the Cousteau shells you've mentioned : I grew up in the 70's in front of a TV set, became a diver because of Cousteau. A common sickness around here I'm sure. Those shells did and still look cool today.

I've being wanting to get one for years. So far, could lay eyes only on 2 of them :

- 1st in the early 90's, was still a student and a beginner diver, I had limited funds and plenty of more pressing stuff to buy, so I let it pass,

- 2nd one, 2 or 3 years ago, prisitine condition, but the price was just plain silly, so I couldn't bother.

Maybe the 3rd one will be the right one.

The shells are hard to find. The At-Pac itself, show up a lot on ebay, search Seapro. From what I've been told, you can source new bladders for them from OMS. Even the old airways can be found, but parts are non-existent. Brass airways can be rebuilt but I would not trust the inner lp hose anymore.

I did a draft history on the AtPac, lots of pictures. It can be found on-line here:

https://personal.filesanywhere.com/fs/v.aspx?v=8d6d638a5f6075b5a46a

"AtPac Watergill Seapro History"

 

[John C. Ratliff]

I have never used an AtPak, but I do have some insights due to a fatal accident in Clear Lake, Oregon in the 1970s. The diver forgot to hook up the LP inflator hose, and went off a rowboat in about 90 feet of water. He was overweighted (diving freshwater, with too much weight). He could not inflate his inflator, and may have had an air problem too (forgot to turn on the air). The interesting aspect about the AtPak is that his weights failed to jettison. Apparently, the lead shot had been in the weight chute for quite some time, and had solidified so as to not come out when the door was dropped. I wanted you to know that aspect of the AtPak's weight system. The fatality was the diver's fault, due to a lot of oversights, but the weight chute problem is something anyone using an AtPak should be aware of.

SeaRat

 

[jadairiii]

I have never used an AtPak, but I do have some insights due to a fatal accident in Clear Lake, Oregon in the 1970s. The diver forgot to hook up the LP inflator hose, and went off a rowboat in about 90 feet of water. He was overweighted (diving freshwater, with too much weight). He could not inflate his inflator, and may have had an air problem too (forgot to turn on the air). The interesting aspect about the AtPak is that his weights failed to jettison. Apparently, the lead shot had been in the weight chute for quite some time, and had solidified so as to not come out when the door was dropped. I wanted you to know that aspect of the AtPak's weight system. The fatality was the diver's fault, due to a lot of oversights, but the weight chute problem is something anyone using an AtPak should be aware of.

SeaRat

That has always been a "complaint" about the At-Pac, that, and the fact that you could only ditch the weights when the diver was vertical in the water column (which to me was the main issue). The years I used mine, in S Florida, I had virtually no lead in the balance box, mainly glass marbles. I didn't need much weight. But I was also diligent is flushing fresh water into the balance box and letting it drain and dry. You could always tell if the shot/marbles were not solidified if they rattled when you moved the pack back and forth. If the diver doesn't maintain their equipment, it will fail them. The At-Pac weight system was no different. Not only was the victim over-weighted, but his lack gear maintenance was a factor also. The solidification was not really a fault of the system, but of the diver's lack of maintenance.

Anyone still using an At-Pac should understand you are diving early 1970's technology and I would hope they are not using the original airway or internal bladder!

 

[John C. Ratliff]

While I haven't used the AtPak, I have two of the Dacor Nautilus CVS (Constant Volume System) that I use yearly in the rivers here. I have not had a problem with the weights, as they are four lead weights in a chute, and the chute is held closed by a lever/pin system. My problem with it is that this pin can inadvertently be pulled, and release the weights unexpectantly (especially when seated on a rock; don't ask how I know).

SeaRat