Diving doubles

[elan]

I often see pictures of divers wearing what seems to me LP 72 s doubles with a wetsuit on a harness. Now I have a question how is the buoyancy swing managed in this case. I can manage one LP72 with 5lb swing in the worst case but 10lb or even 7-8 lb seems impossible.

I usualy dive dry so extra lbs can be done by the suit but I plan to get a proper wet suit soon and was wondering how you guys do it.

What is the solution ? horse collar ?

Thanks!

 

[Akimbo]

The vast majority of horse collars were for surface inflation rather than function as BCs, before the early 1970s anyway. There were lots of techniques but for me, doubles meant deeper decompression dives, most often off a boat. If I was on a beach it would have a fast drop into deeper water. I would weight myself light at the surface and swim or pull myself down a line. Suit compression would make me a little heavy on the bottom.

By the end of the dive I would be neutral to a little light, which was about the time to head to the first stop. The wetsuit would expand but I had a down or anchor line to hang onto, or was swimming back into shallow water towards the beach and could pick up some ballast if necessary.

The big difference is that Rubatex wetsuits didn’t compress nearly as much as today. Another factor is we were wearing double 70s rather than 100s to 130s like today (less air, less weight change). Secondarily we weren’t so paranoid about touching the bottom and causing irreparable harm to the entire universe as is in vogue today.

 

[elan]

Thanks Akimbo, I heard once from a person that it was ok to weight to be light at the end and pick up rocks or hold on to the line when surfacing... hm i need to rethink it..

 

[simonbeans]

If you are diving at a location where your entrance and exit are the same place, you can use drop weights to compensate for the wet suit loss of bouyancy at depth. Also, rocks are fabulous added ballast. And if you need bouyancy at depth, you can use what is handy, like my buddy in the St. Lawrence:

 

[Eric Sedletzky]

I carry around rocks.
If I don't have a rock that means I either have a big lingcod on my stringer or a load of scallops in my goodie bag.
Diving a single light is the same as diving doubles light. It's just that with doubles there's a little more weight swing than a single so you need to weight much lighter so when you first get down with full tanks the bouyancy is the same, then when you drain the doubles you are lighter than you would be with a single so you carry around bigger rocks.

So I guess you could say you have to have big rocks to dive doubles with no BC. :shocked2:

 

[elan]

Looks like I need to practice this skillsbefore going doubles

simonbeans where in St Lawrence do you, guys, dive ? May be I can join you one day of you do not mind, I live in Montreal now

 

[simonbeans]

Most of the time we are in the Alexandria Bay Area. But get to Brockville in August most years. A couple of us are going to be in Alex Bay the first 2 weeks of July. PM your email and I can keep you informed.

 

[DA Aquamaster]

I was a skin diver for a few years before (officially) moving to scuba and I think that was a lot more common then than now. The upside of that was under standing proper weighting and how to take advantage of wet suit compression.

For example, skin or scuba, you weighted yourself so that you floated vertically at eye ball level with full lungs (at the end of the dive with near empty tanks with scuba). When you exhaled you sank, and at about 15-20 ft with full lungs you were now neutral due to wet suit compression. That made it easy to decend, did not leave you excessively over weighted on the bottom for most of the dive, was very hand for the end of the dive deco stops, and allowed you to rest on the surface at the end of the dive, even without other floatation.

The volume of a wet suit is not as linear as air and, particularly with older suits, they were more or less fully compressed by the time you got to 60 feet or so.

There was a greater tolerance of being heavy and touching bottom during the dive, but the swing weight from even double 72s can start to be a problem. If you used the whole 144 cu ft, you'd have 11.6 pounds of swing weight and with a 500 posi reserve, you still have a 9.2 pound swing weight and that is more than you can efficiently compensate for with lung volume. On the other hand most people in good shape could swim 10 pounds off the bottom.

However by the mid 1960s horse collar BCs were fully intended to be used for buoyancy compensation, not just surface floatation, power inflators were the norm by 1970 and few companies had integrated BCs on the market in the early 70s.

In that regard, when doing vintage doubles dives, I use a horse collar to allow precise buyancy control without compromising breathing efficiency.

 

[Akimbo]

…However by the mid 1960s horse collar BCs were fully intended to be used for buoyancy compensation, not just surface floatation, power inflators were the norm by 1970 and few companies had integrated BCs on the market in the early 70s...

The first buoyancy device that I saw that could be inflated at depth and had a pressure relief valve was the Bouée Fenzy. It was sold for, and used as, an emergency inflation device because there wasn’t enough air in the little HP bottle for normal compensation throughout the dive. There was also no way of knowing how much was left in the small bottle so it was imprudent to use it as a BC in case you actually needed it for an emergency.

The Bouée Fenzy was first advertised in Skin Diver Magazine around 1968, but were very expensive. I never saw them used by recreational divers, only pro and semi-pro photographers. I received a Bouée Fenzy as an extraordinarily generous gift from the importer in mid-1969. I have personally only seen three of this model in use. The BC labeled simply Fenzy quickly replaced Bouée Fenzy in the very early 1970s.

I don’t recall significant use of horse-collar BCs until inflators replaced the HP bottle. Even then they were unusual. We would take power/oral inflators off early Neoprene dry suits (O’Neil??) and replace the oral inflator on the Fenzys long before I saw it as a commercial product, probably around 1974. This preserved the small bottle for emergency use so we could use it as a BC. The first jacket BCs I noticed was very late in the 1970s and into the 80s, at least on the west coast.

 

[Luis H]

I started using a Fenzy in late 71 and totally gave it up about 6 years ago… I liked it for surface flotation, but I have always used it as a BC as needed. It is a horrible BC because the volume behind the neck is too large and any air will go there. Obviously, I never put too much air (if any) in it or I would have given it up many years ago.

The issue about not being able to monitor the air inside the small cylinder was always a concern, but I never ran out of air. I was actually never concern about running out of air and needing it for an emergency, but I didn’t want water to enter a empty cylinder.

The picture on the left of my avatar is from about 1972 with my old Fenzy (it is leaking at the seams). The one on the right is from 2005 (with a Fenzy I bought a few years back). The regulator and snorkel are the same.


Sorry about the hijack… back to doubles.