What do you do on double dives?

If your using a twinset and going on a double boat dive what do you do?.

Do boats allow 2x twinsets on?

Take a 15l or a HP tank and top it up. You shouldn't need very full tanks for the second dive.

If I use my doubles on a regular 2 tank boat dive I usually have plenty of gas left over from the first dive to do a shallow second dive. The shop I usually dive with doesn't have a problem with my using doubles if I let them know I want to get a little practice in with that gear.

Scott

dive twice off of a commercial boat. Sometimes my second dive is a tad shorter or I am a little lower on air than I would like at the end. I seem to manage.

72 c/f = 10L??

I have a 10L twin set that I havnt dived yet but im looking to get some practice in on a smaller set of tanks.

I think they might be a little small for me on 2 dives though...

Prepare once bubbled...
72 c/f = 10L??

I have a 10L twin set that I havnt dived yet but im looking to get some practice in on a smaller set of tanks.

I think they might be a little small for me on 2 dives though...

Click to expand...

72 c/f might be a little small. I use a set of Aluminium 90's and even with a nitrox fill to extend my bottom time on the first dive of over 100 ft I seem to have more then enough for a second dive to 30 or 40 ft. Of course how long your tanks will last you depends on several factors such as depth and breathing rate. If you already have the tanks set up try them on the first dive, bring along another single tank just in case and if you don't think there is enough gas left in the doubles to do the second dive switch to the single.

Scott

...Shane and I have found that when diving off of a boat with other single tank recreational divers we have plenty of gas to do two dives with one set of doubles. And since we only need to have one Rock Bottom in reserve we actually have more time than if we were diving the same tanks as singles.

We have done boat dives were we did two small deco dives while the other divers did their rec. dives and planned it so that our total time (including deco) corresponded with the BT of the others. We would go in first and get out last. Since it was a live boat drift dive we were not constrained by a rule of thirds.... just needing rock bottom. We also had enough gas in our single AL40 deco cylinders to do both dives but if something would have gone wrong with them we would have just extended the deco on back gas.

I will say that it is more convenient in most cases to dive singles if you are on a boat with other folks diving singles.... the boats we were on were set up to handge doubles as well.