How to configure twin 7's?

[Justin Owen]

Dom, am i right in thinking you converted the over-pressure valve on the right shoulder to a dump valve? If so how did you go about doing this? Mine seems to be glued/welded down...

Thanks...

[Dominic]

Yes and no.

I did it as an experiment, found it didn't work very well, and converted it back to a simple OPV. However, YMMV:

It ISN'T glued or welded, but it IS bloody tight. I used mole grips (or pliers or whatever they're called) in the end (with a bit of rubber to prevent damage) to get the cover undone.

Once you can unscrew it, it's plain sailing. The difference between an OPV and a dump valve is: One has a piece of string, the other doesn't.

Knot a bit of string, thread it thru the bits that have holes for a bit of string, re-assemble the dump valve, and voila! A dump valve!

However, I couldn't find a good way of routing the dump cord, so I eventually took it back off and just dump from the corrugated hose these days. . .

[Whatgoesdownmustcomeup]

My first twin 7 configuration was on a pioneer td bolted through the plastic backplate but there were two niggles that made me move over to an oms wing.

The first was the general sloppiness of the rig in the water. Even with everything done up tightly it tended to want roll off my back all the time which restricted me from anything other than normal horizontal finning most of the time.

The second was the imbalance of the buoyancy. Because the buoyancy on the AP Valves ABLJ's is beneath the arms then it's not really usefull for anything other than surface support and therefore you have to use your drysuit for all the buoyancy control and this means the entire load of the twinset is pressing down through you and is very uncomfortable.

I now dive manifolded twin sevens with an OMS wing with aluminium backplate (virtually no heavier than the pioneer) but use the wing for the majority of buoyancy control and only just enough gas in my suit to eliminate the squeeze. The wing takes the weight of the twinset and even with a couple of Kg of lead bolted to it I hardly notice that it's there now!!! Soooo Comfortable!!!

You will never go back if you get it right.