8-10LBS in SW. Ive never dove FW but will be???

[Vampyre]

So last i was diving i was using 8-10 lbs in a 3mm exposure gear, depending on current/conditions. All of my dives (100ish) have been in SW. Ill be doing my first FW dive and most of my future dives in FW (Ive moved away from the coast).

Now I'll be in a 7mm hands, booties, wetsuit and 5/8 chest hoddie. With my mm changing from 3 to 7 and with the everything else being the same, what weight should I shoot for? I dont want to show up to my first FW group dive not being able to stay down.

 

[devilkitty]

What kind of cylinder are you planning on using? Any change from your SW rig?

You'll need less weight in FW, everything else being equal.
Thicker exposure protection will require a weight increase, again, everything else being equal.

For the SW-FW change and the thicker suit to cancel each other out exactly would be convenient, if highly unlikely. Thus, I'd add a few pounds to start: try 12-14 or so; it's better to be a little negative than unable to get down. Take the weight in two-pounders if you can; then drop or add as you need to after the first dive.

 

[Bob DBF]

During the dive planning with your buddy let him know you are working on your buoyancy. Do a weight check before you dive and add weight for the swing in buoyancy of the tank and weight of the air. Have your buddy carry an extra 5# in case. At the end of the dive do a weight check @ 15' and dial it in.

Bob

 

[Scared Silly]

Go to the local dive shop and hop in the pool. Go in with your 3mm suit and see how much weight it takes to sink. Then do the same with your 7mm. The difference is what you will need to add to what you previously dove in SW with your 3mm. Note: I am not adjusting for the FW/SW so the additional weight will be slightly more than you need. but do as suggested carry some of the weight in your front pockets (2-2lbs) so you can fine tune.

 

[redacted]

The change from SW to FW is a weight change of about 2.7 % of your total system weight (you and you gear). That is probably in the 5 to 8 pound range. But changing thermal protection is not as predictable unless you measure the buoyancy of all your neoprene. A 3mm jumpsuit probably has an inherent buoyancy in the range of 5 to 8 pounds depending on size and materials. A 7mm suit is probably in the range of 12 to 30 pounds buoyant depending on size, material and style (jumpsuit vs, 2-piece). All my neoprene goes in the pool and gets inherent buoyancy measured when I first buy it and again periodically as it ages.

 

[Firefyter]

FWIW, I wear the same weight in 7mm FW as in 3mm SW. I know everyone is different, and you'll have to add weight for core warmers or vests, but it's a reasonable place to start. Best advice, though, is to get in a FW pool and check it out.

 

[RonFrank]

I wear 20~24lbs of weight in a Drysuit in Fresh. The variable amount is based on additional stuff. If I wear a hood, and 5mm gloves I up my weight a bit.

I wear 8~10 lbs of weight salt water in a 3mm fullsuit.

Your results WILL vary. My best advice, dive heavy initially.

Being a few lbs overweight will not bother most divers. Diving a few lbs light WILL cause problems.

It is ironic that so many divers strive for that thin line between perfect balance as the tank volume is depleted, and under-weighted. Seems most would rather be under-weighted vs. over-weighted... until they are.

Let me tell you being under-weighted is a fools game.

My suggestion, add 10lbs, than add 5lbs more! If you can get your buddy to carry the extra weight do that, but better too heavy than too light. Also once you burn a tank, do a buoyancy check (most likely the end of the dive).

 

[JohnB47]

I have found that the wetsuit buoyancy chart in the University of Michigan Research Divers Manual is quite useful. You can find the manual online (access is free). You will have to scale it for metric sizes, since it just shows 1/4" and 3/16", for various suit sizes.

Without knowing what size suit you wear, how much you weigh, and what kind of tank you have used and will be using in the future, it is hard to calculate the weight requirements accurately. However, my guess would be 14-15 lb. (YMMV)

 

[Vampyre]

It ended up being 20lbs with 7mm suit 5mm gloves 7mm boots 7/3 vested hood