Can you give me a weight estimate

[jstuart1]

I leave on my cruise on Sunday and will be diving in Key West, Grand Cayman and Cozumel. These will be my first salt water dives and I am looking for a weight estimate. With an Al80 and a dive skin, I use 17 lb in fresh water and 23 with a 3mil suit. (Just lost a pound with comfort level). About how much weight will I need in salt water with my skin. (I guess the 4lb for 3mil still applies should I wear my suit. Any help would be appreciated as I really hate to tell them I have no idea how much weight I will need. BTW yes I am a pretty big girl hence all the weight.

Thanks
Judy

 

[Rick Murchison]

The additional weight you will need is equal to your total weight with all your gear and weight for fresh water times .025.
So, if you and your tank and BC and weights all together weigh 200 pounds, you'll need to add 5 pounds to your fresh water weighting to be neutral in salt water. If you and all your gear weigh 240, add 6 pounds; 280 add 7 pounds, and so on.
Rick

 

[Drew Sailbum]

... I really hate to tell them I have no idea how much weight I will need. BTW yes I am a pretty big girl hence all the weight.

Thanks
Judy

Dive staff are reasonably well versed in this issue and really don't mind. Whatever number you come up with, take the time to put it to the real-world tests:

1. Start with a weight check. After you enter the water, vent all of the air from your BCD and cross your legs (so you don't kick up). You should start going down at a "reasonable" pace. Ask the DM to keep an eye on you while you do this. If you just barely get under or need to exhale hard to sink, then you need more lead. You'll only get more positively buoyant as the dive progresses adn you use your air.
2. Do a double check at your safety stop. By the time you are down to your surfacing pressure (often 500psi) you should have essentially no air left in your BCD at all. (Perhaps some to account for wetsuit compression, but not much!) If you still have lots of air in your BCD, try dropping some weight for the next dive.

Please mention that it will be your first saltwater dives and remember to keep a log so you can refine your weighting over time.

 

[Dive-aholic]

Guessing the 17lb in fresh water is with a skin. If that's the case, add 5lb and do your buoyancy check. As already mentioned, don't be embarassed about telling the DM this is your first salt water dive. Let them know where your extra weights are and add or subtract as you need to. You should be able to do this without even getting out of the water.