Please help me with a weight question

[Joe Cool]

Artimas,

I dive in the PNW and use basically the same set-up as your except that, up until today, I was using an Aluminum 80 tank. According to my LDS, a good estimate of how much lead to use is 10% of your body weight + 12-lbs. So, for you, this would be roughly 30-lbs. I recommend doing a bouyancy check in the ocean and probably start with 34-lbs. You won't have that much bouyancy variation with your steel tank. As a benchmark, I am 6-ft. 2-inches tall at 190-lbs. I have a medium build body. If I use 38-lbs. with my AL80 tank, I am a dead weight on the bottom. I just used 33-lbs. today and I am too positive by the end of the dive. I believe with a steel tank, my bouyancy by the end of the dive would be very close to neutral.

Phil

 

[Artimas]

Thank you for the replies.

40-50# still seems like a lot of weight.

I think I'm going to try a very shallow dive in seawater with my full rig to try and work out the weight problem. I feel as though that's going to be the only way to know for sure. If I really only need around 35#, I don't want to carry 40-50, while if I need 40-50, 35 would be dangerous, if not impossible to dive.

It's too important to be guessing on a thing like this.

 

[cave_diver]

That’s a lot of weight. How is your trim in the water? How is your breathing? A 130 steel is a big and heavy tank and you should be able to really shed some pounds if you work on it. Diving with less weight will usually benefit your air consumption and your position in the water. If you can keep you buoyancy in 10 feet of water with 500 psi or less in the tank, no air in your BCD, and your lungs half full, you have enough weight. This means you should be able to control your buoyancy by inhaling and exhaling. Again, you have to try this with an almost empty tank, since the buoyancy of the tank will change during the dive.

 

[nereas]

Thank you for the replies.

40-50# still seems like a lot of weight.

I think I'm going to try a very shallow dive in seawater with my full rig to try and work out the weight problem. I feel as though that's going to be the only way to know for sure. If I really only need around 35#, I don't want to carry 40-50, while if I need 40-50, 35 would be dangerous, if not impossible to dive.

It's too important to be guessing on a thing like this.

I have known of one person on this Earth who required 45 lbs. He is 6 1/2 feet tall however.

36 lbs is not uncommon for a thick new wetsuit, though.

 

[spectrum]

Artimas,

I dive in the PNW and use basically the same set-up as your except that, up until today, I was using an Aluminum 80 tank. According to my LDS, a good estimate of how much lead to use is 10% of your body weight + 12-lbs. So, for you, this would be roughly 30-lbs. I recommend doing a bouyancy check in the ocean and probably start with 34-lbs. You won't have that much bouyancy variation with your steel tank. As a benchmark, I am 6-ft. 2-inches tall at 190-lbs. I have a medium build body. If I use 38-lbs. with my AL80 tank, I am a dead weight on the bottom. I just used 33-lbs. today and I am too positive by the end of the dive. I believe with a steel tank, my bouyancy by the end of the dive would be very close to neutral.

Phil

First of all if you're going to quote rule of thumb you need to qualify the gear and water. A warm pond in a shorty is very different from the ocean in 7mm with 2X on the core.

Second the cylinder material has nothing to do with the swing. If he has an 80 CF cylinder and uses 70 he will be 5.6 pounds lighter regardless of cylinder type.

 

[spectrum]

Thank you for the replies.

40-50# still seems like a lot of weight.

I think I'm going to try a very shallow dive in seawater with my full rig to try and work out the weight problem. I feel as though that's going to be the only way to know for sure. If I really only need around 35#, I don't want to carry 40-50, while if I need 40-50, 35 would be dangerous, if not impossible to dive.

It's too important to be guessing on a thing like this.

For the record... My answer based on your weight check was not a guess, it was physics. I agree that the weight check is suspect.

Keep to conservative depths until this is sorted out.

Pete

 

[Artimas]

Pete-

I realize your answer was calculated and not a guess. I just don't feel comfortable with MY pool test at this point, it just doesn't make sense. It would be too potentially dangerous for me to go ahead and dive without having complete confidence that my weighting is safe and reasonable.

I always have had good trim and reasonable air consumption before the new wetsuit, so something seems amiss. I don't know what could have been off, but I just don't trust it, and need to try it again.

Thanks to all who replied. I'll try another pool test before diving, probably next weekend.

 

[Buddhist_Monk]

I can tell you that 10% of body weight was way too much for me. I remember my LDS telling me to take 20lbs. I dive with 8 lbs.

Being too heavy is dangerous, screws up your trim, creates drag and makes you work harder under the water. Do yourself a favor and throw a bunch of weights over the side of the boat and spend one dive dialing in your weight. Add and drop in two pound increments.

IMO, this should be mandatory. I have seen so many people weighed down with unnecessary weight.

Once your get your weight set your dive will be much more enjoyable.

BM

 

[Artimas]

An update.

In the pool with full 7mm John and jacket (2x on core), with hood, gloves, boots, 130 cf tank (full), pony and fins, I needed 28# to get neutrally buoyant at 9 ft.

I'll add 6# for salt water, and 10# for the air in the tank, to get 44#.

I'll use that as a starting point and fine tune after the dive with an almost empty tank.

Seem reasonable?

 

[hudson]

My suggestion is don't worry about it until you have about ~15-20 dives in the new 7mm.

This stuff loses A LOT of buoyancy early on.