Weighting Question

[GrumpyOldGuy]

FYI: My son is close to your size (248lbs), needs 18lbs in a 3/2 with an AL80 in salt water. However, he is a very relaxed diver. If you are a newer diver and being in relatively shallow water, you may want more (20lbs?) to start with. My estimates, like the others are wild guesses, the only thing I add is the scaling for big guys as the rules-of-thumb don't always work for the biguns in XXL or XXXL big boy bags. In the end, nothing will subsitute for a proper weight check.

 

[sdorn]

I am 6'4" and 265lbs, 3mm Full Wetsuit, mostly will be diving in South Florida salt water. What is a guesstimated weight to start with??

Guesstimate is about 15lbs. I match up pretty closely with your description of yourself and your gear, except my height is lower at 5'10" and I recently used 17lbs on a dive in the Bahamas. I was a little overweighted and probably needed to drop about 2lbs. I was in a full 3mm with an AL80 as well.

Just took a buoyancy class and could actually get down in the pool with only 2lbs with all my gear and an AL63. I had to expel almost all of my air to do it, but I could get down. I went back to 4lbs and could easily get down. If you add around 6lbs for the air and 6lbs for the salt water, that gets me back up to around 16lbs for diving in the ocean.

 

[SkimFisher]

Don't use any formulas\guesstimations. Get in a pool with an almost empty AL80 and find out first hand. Otherwise 9x out of 10 you're going to end up as an anchor and severely over weighted. (Even if it means you have to bleed the tank down by hand - no one expects you to sit in a pool for 4 hours.)

According to all these formulas - with my body weight, 3mil wetsuit and hood and an AL80 - I should be diving with 16lbs of lead. But I don't - because I only need 8 lbs with an empty AL80. Which is why buoyancy checks are a must.

 

[mclir9]

Yes, I was wearing everything and the tank was full close to 3,000. My BC was empty.

 

[Bubbletrubble]

OK. You did a weight check using a full AL80 in a pool (fresh water) and determined that you needed 14 lbs. of lead.

Add 6 lbs. to compensate for the air in your tank. (14 + 6 = 20)

For fresh water to salt water conversion, add enough lead to be equivalent to 2.5% of the total weight of you + all of your gear.

After you do this, you'll probably end up wearing 14 + 6 + 8 or 9 = about 28 lbs. of lead.

28 lbs. seems like a lot, but if that's what it takes, then that's the right amount of lead for you. I'd start there with the weight-check. Add/subtract lead in small increments to dial it in.

Remember that the goal of being properly weighted is to be able to comfortably hold a shallow depth (safety stop depth or shallower) with an empty BCD and a near empty tank.

Good luck and have a great time...

 

[k ellis]

I would say that it takes trial and error. I used to need 14 pounds to get me to sink. Then I got to 12 pounds. I used 12 pounds in Cozumel and lost 1 3 pound weight and was still able to make the dive comfortably. Funny thing is with my bcd and set up I can dive without weight in fresh water. For this reason Id say I love my Aeriees coral BCD as its perfect for diving.

To answer your question though one important after thought would be when you achieve the perfect weight be sure to document it for future use and it will help make future dives easier

 

[theduckguru]

I am 6'4" and 265lbs, 3mm Full Wetsuit, mostly will be diving in South Florida salt water. What is a guesstimated weight to start with??

I'd start with 18, you'll be within 2+/-.

 

[weitodive]

I generally teach with a little bit of extra weight on the divers at first. Once your breathing and comfort level start to settle in, then you can drop actually quite a few pounds. With a 3mm and a full al tank, I would say between 15-20 pounds. It's generally better to be a little heavier in the beginning in my opinion.

 

[SkimFisher]

BTW - on a side note. After reading this thread and some of the numbers thrown out I decided to do a little experiment.

I went home last night and tested this "6lbs for an AL80" theory in the pool. I emptied the tank to 500 PSI and tossed it in.

To say that it was even +1 positive is an overstatement. As soon as it steadied a$$ up in the water I tossed a 1lb bag of lead on it and it sunk like a rock.

Granted in saltwater it would be a bit more buoyant. But 6lbs?

 

[Bubbletrubble]

I went home last night and tested this "6lbs for an AL80" theory in the pool. I emptied the tank to 500 PSI and tossed it in.

To say that it was even +1 positive is an overstatement. As soon as it steadied a$$ up in the water I tossed a 1lb bag of lead on it and it sunk like a rock.

@SkimFisher: I'm not going to say that the tank buoyancy spec charts posted on the WWW are 100% accurate, but I don't think that they're 6 lbs. off either. Bear in mind that I'm not a tank expert or anything...

Here's the link to the TechDivingLimited.com tank specs webpage. Take a look at it.

It is entirely possible that you have a Catalina C80 tank, designed to be neutrally buoyant when empty.
The other possibility is that your tank has a tank boot on it that's "hiding" some lead sandwiched between the boot and the bottom of the tank. People sneak that weight in there in order to counteract the way that many AL80s get butt light when empty.

Most of the AL80 tanks that I've encountered are either Catalina S80s or Luxfer 80s. I believe that the C80s are not quite so ubiquitous. I think that's why people generally say that AL80s are -2 lbs. buoyant when full and +4 lbs. buoyant when empty. The weight swing from full to empty is about 6 lbs.

(And, to clarify, the buoyancy specs that I've quoted were determined in salt water. In fresh water, the tanks will be slightly [1 lb.?] more negative.)