OP
HenrikBP
Contributor
Thanks all for your thoughtful replies. The DIR answer was what I was looking for. I guess I was asking "hoping against hope" 
Thanks DA for all your weight calculations. It is obvious that I missed a bunch of weights and considerations in my own calculations. I had based my numbers off of weighting notes in my logbook, unfortunately forgetting things in the process. A good reminder for me to make sure I go all the way back to "basics" when doing these calculations/estimates.
In my 3 mil alone diving salt water with a single AL80 on a steel plate I use 7 lbs of lead - 4 in trim pockets and 3 on the belt. In NC I will be adding a 3 mil hooded vest - adding maybe a pound or so of buoyancy. Going from single to doubles I add a second regulator (-3 lbs), bands and manifold (-4 lbs).
<edit> missed something ... again ... really need to sit down and do the #s.
The -7 lbs in 2nd reg/bands/manifold would make up for the 7 I wear with a single. But then I would need to account for the ~4 lbs of positive buoyancy of an additional empty AL80. Meaning I would need 4 lbs of weight.
I figured I would leave reel and other non-secure items out of the "ballast" calculation since they could be lost during the dive and possibly leaving me light at the end of the dive.
I have no experience diving with a stage/deco bottle and wanted to keep new skills out of the picture. So I had considered bringing a single HP100 and trans-filling to the doubles between dives.
I dove a couple of days in NC last year using single HP120 tanks. The outer banks wrecks we dove were in the 100' - 110' range. On those dives I used at most 80 cu. ft. total with a nice slow minimum deco ascent and long 10' stop. I had also planned to leave the bottom with no less than 40 cu.ft. in the tank.
Using those numbers and figuring 154 cu.ft. in AL80 doubles I figured I would use 80 cu.ft. on the first dive. A trans-fill from a full HP100 would add ~650 PSI to the ~1400 PSI I would have left after using 80 cu.ft. So I would start the second dive with about 105-110 cu.ft. in the doubles - a tad shy of the 120 cu.ft. I would like but in reality probably enough.
As for temps; in September I noted bottom temps in the upper 70's on the outer banks dives. The one dive we had on the Indra was - as DA mentioned - considerably colder. I was shivering and thumbed the dive after 50 minutes.
Thanks again everyone,
Henrik
Thanks DA for all your weight calculations. It is obvious that I missed a bunch of weights and considerations in my own calculations. I had based my numbers off of weighting notes in my logbook, unfortunately forgetting things in the process. A good reminder for me to make sure I go all the way back to "basics" when doing these calculations/estimates.
In my 3 mil alone diving salt water with a single AL80 on a steel plate I use 7 lbs of lead - 4 in trim pockets and 3 on the belt. In NC I will be adding a 3 mil hooded vest - adding maybe a pound or so of buoyancy. Going from single to doubles I add a second regulator (-3 lbs), bands and manifold (-4 lbs).
<edit> missed something ... again ... really need to sit down and do the #s.
The -7 lbs in 2nd reg/bands/manifold would make up for the 7 I wear with a single. But then I would need to account for the ~4 lbs of positive buoyancy of an additional empty AL80. Meaning I would need 4 lbs of weight.
I figured I would leave reel and other non-secure items out of the "ballast" calculation since they could be lost during the dive and possibly leaving me light at the end of the dive.
I have no experience diving with a stage/deco bottle and wanted to keep new skills out of the picture. So I had considered bringing a single HP100 and trans-filling to the doubles between dives.
I dove a couple of days in NC last year using single HP120 tanks. The outer banks wrecks we dove were in the 100' - 110' range. On those dives I used at most 80 cu. ft. total with a nice slow minimum deco ascent and long 10' stop. I had also planned to leave the bottom with no less than 40 cu.ft. in the tank.
Using those numbers and figuring 154 cu.ft. in AL80 doubles I figured I would use 80 cu.ft. on the first dive. A trans-fill from a full HP100 would add ~650 PSI to the ~1400 PSI I would have left after using 80 cu.ft. So I would start the second dive with about 105-110 cu.ft. in the doubles - a tad shy of the 120 cu.ft. I would like but in reality probably enough.
As for temps; in September I noted bottom temps in the upper 70's on the outer banks dives. The one dive we had on the Indra was - as DA mentioned - considerably colder. I was shivering and thumbed the dive after 50 minutes.
Thanks again everyone,
Henrik
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