Help with proper weighting for tropical diving

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ccohn2000

Contributor
Scuba Instructor
Messages
151
Reaction score
1
Location
SF Bay Area (CA)
# of dives
1000 - 2499
Hi All,

All my dives so far (only 59 so I'm still a newbie) are cold water. I wear a 7ml wetsuit, a 5ml corewarmer and a 12 ml hood. I usually wear 10lbs of weight with that plus my bp/w (Halcyon Eclipse) and I think I still might be about 2lbs over-weighted, because I will sink during a safety stop with no air in my BC. My tank is a steel 80 though and usually not at 500 psi. More often than not it's 800 or more. Anyway I'm leaving for Cozumel on Saturday and trying to figure my weighting without the wetsuit and hood. I'll still have the core warmer and maybe a skin since I also worry about sunburn. I went into my pool the other day with that configuration (no skin) and no weights. I sank like the proverbial stone. I have no ditchable weight and I'm still really negative. Is that a problem or am I obsessing over nothing?
 
ccohn2000:
Hi All,

... I sank like the proverbial stone. I have no ditchable weight and I'm still really negative. Is that a problem or am I obsessing over nothing?
The latter :)
If you can, try hitting the pool with a skin and an AL80, near empty, get your proper weighting. (AL80 is what you'll likely dive in Coz) There's a decent difference in buoyancy between an AL and a steel -- AL is multiple pounds more buoyant.

Depending on your size, going to salt is likely to take about +6 lb of weight compared to what you need in the pool. +6 is for me, 180 lb male. Add or subtract another 1 lb for each 40 lb your weight differs from 180.
(In other words, I use 4 lb fresh, 10 lb salt. If I weighed 220 lb, 4 lb fresh would equate to about 11 lb salt)

The above should be "pretty close". As always, you then do a check on your first dive.

To get a feel for tank buoyancy characteristics, you could check:
http://www.huronscuba.com/equipment/scubaCylinderSpecification.html

(A more correct method is to get your fresh water weighting, then get the land (dry) weight of you plus all gear, add 2.5%. The 6lb more-or-less approach is just simpler.)

By all means take the core warmer, but you may well not need it if you run at all warm.

Have fun!
 
Tell your DM you are new to warm salt water diving... they will take care of you. I recommend overweighting by prolly 4 lbs at first, but then really working with the DM to find the right weight for a 15 foot rest stop at 500 psi. Most of the diving there is drift, so the rest stops are on the move... buoyancy control is important.

That said, I think you'll be surprised how much less weight you need. :)

Have you picked a dive op yet? If not, you can't go wrong with Aldora Divers.
 
If your current cold water weighting is in salt water, you probably will be negative with no weights without the neoprene. No biggie; in fresh water and a shorty I'm pretty negative with my plate and no weight. It took me a dive to get used to it, I bet the same thing will happen with you.

One thing I found using my plate in Cozumel with almost no neoprene was that getting down at the beginning of the first dive was so easy I thought I must have been overweighted, but sure enough I was pretty neutral for my safety stop.
 
Thank you for your responses. I feel much better now! I was really worried about not having any ditchable weight. I've done a weight check in my pool before when I got my new wetsuit and I seem to only need about 2lbs more in the ocean than I do in the pool. I really don't mind sinking at the beginning of the dive, it's sinking during the safety stop I was worried about. I can offset that with air in the bc though. The only time I dove aluminum tanks was during my open water. Now I'm worried about being underweighted. I think I'll just calm down and deal with whatever as it comes. I'm really looking forward to diving where I can see forever and don't have to carry instant hot packs to make my dive last longer. Thanks again, I really appreciate the help. You guys all totally rock!
 
Hey you,
You know...you could have used that aluminum plate of mine.
 
Hi All,

Thanks Andy, I forgot you had an aluminum backplate. I would have been too lazy to reweb my BC though I think. Mattboy's experience was pretty close to mine. I had no neoprene, I just used a skin. I was negative the whole time though, even at my safety stop. Didn't really bother me though, I just kept a little air in my BC. On my first dive I was a little worried that with the aluminum tanks I would be light at my safety stop, so I was actually relieved when it turned out the other way. Great diving though! Thanks again for all your help!
 
https://www.shearwater.com/products/peregrine/

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