How to approximate amount of weight needed and weight placement

[Kenderson]

So I have two questions, both kind of related to each other.

I just got a new BP/W and used it for the first time over the weekend. I dove in a 7mil wetsuit my aluminum BP. I went diving in fresh water and used a total of 9 extra pounds. I think I hit the sweet spot as I was able to go under, but it was a nice slow descent and I wasn't constantly pushing up to keep off the bottom. I tried 10 pounds for one dive and it made it harder to not hit the bottom.

How do I determine my weight if I go from fresh water to salt using the same setup? I just need a ballpark and can work it out from there. What about if I ditch my wetsuit, how much does that change the weight for fresh water and salt water? I did see the spreadsheet that's floating around the boards, but when I tried to use it I think I got some really strange results.

Now for weight placement. I put six pounds on the upper cam band, three on each side, and three pounds on a weight belt. Is that too much weight on the bands, the right amount, not enough? When using a BP/W do people use a weight belt or do they put weight pocks on the waist belt? I was thinking that I would get two weight pockets so I could ditch some weight if needed.

 

[martincohn]

Optimal Buoyancy Computer

 

[lexvil]

It depends on how much “float” your 7mm has which depends on your size, ballpark add 2 to 3% for salt.

 

[James79]

I recommend using this document, by @rsingler with help from others:
Optimal Buoyancy Computer
I adjusted my copy to match actual weight used at the springs, and then just changed the conditions to salt.... presto, good data! Once you get your personal buoyancy dialed in it also makes a great starting place for estimates after a gear change.

Make sure your weight checks are with minimum air in your tank (300-500 psi), so you don't find yourself too light at the end of the dive. Or do the check with a full tank, and add lead for the weight of air in the tank.

Regards placement, my usual dive buddy and I validated/adjusted placement when we did our weight checks.... 500 psi tank, 15 feet, can I hover with an empty wing? check. Stop all movement and see what happens... went vertical - shift weight higher, go head down - shift weight lower, turn turtle - move weight to front of body, trouble rolling over - move weight to cam-band or plate.

Respectfully,

James

 

[TooManyHobbies]

Do you have an STA on the backplate? I'm guessing probably yes.
A 7mm wetsuit, depending on your size, is about 10-12lbs buoyant in freshwater by my observations. The computer linked above will have the fresh-salt conversion.
Having 2/3 of your weight that high is more than most people have, but if it works for your trim, there's no issue. I usually throw most of my weight on the upper cam band as well. My legs are very dense so I need the ballast up high. @James79 is exactly right about how to verify that.

I see you're in Maryland. If you have anything you want to work on face-to-face, PM me and I'll see if we can find a place to dive together.

 

[Doc]

Dive often.

Keep notes.

 

[scrane]

The bottom line (no pun intended) is you should set your weight so you can easily maintain your safety stop with little or no air in your BC. It is not good to be grossly overweight, but you are better off being a little bit heavy, especially if you are a new diver. Add a pound or two for salt water and fine tune from there.

 

[Kenderson]

The bottom line (no pun intended) is you should set your weight so you can easily maintain your safety stop with little or no air in your BC. It is not good to be grossly overweight, but you are better off being a little bit heavy, especially if you are a new diver. Add a pound or two for salt water and fine tune from there.

Thanks, this is what I was looking for, a ballpark estimate so when I do go somewhere else. I just want to make sure that if someone tells me I need an extra 20 pounds I know that's too much. I know I need a lot more diving to figure out how to really dial it in.

Optimal Buoyancy Computer

I did download that, but there's a lot of info in there that I don't fully understand. The first couple of times I tried to use it it told me I needed 20+ pounds. I couldn't get it to come close to what I had weight wise. I know that it's because I didn't input all the correct information.

Do you have an STA on the backplate? I'm guessing probably yes.
A 7mm wetsuit, depending on your size, is about 10-12lbs buoyant in freshwater by my observations. The computer linked above will have the fresh-salt conversion.
Having 2/3 of your weight that high is more than most people have, but if it works for your trim, there's no issue. I usually throw most of my weight on the upper cam band as well. My legs are very dense so I need the ballast up high. @James79 is exactly right about how to verify that.

I see you're in Maryland. If you have anything you want to work on face-to-face, PM me and I'll see if we can find a place to dive together.

No, I got the Dive Gear Express BP/W that doesn't need or come with the STA. My legs do tend to sink, especially with the fins I have.

I'm over in Montgomery county off of 270. Are there any places to go besides Phoenix and Dutch? At least places with somewhat decent vis?

 

[TooManyHobbies]

No, I got the Dive Gear Express BP/W that doesn't need or come with the STA. My legs do tend to sink, especially with the fins I have.

I'm over in Montgomery county off of 270. Are there any places to go besides Phoenix and Dutch? At least places with somewhat decent vis?

What fins do you have? I was diving Power Planas and switched to Go Sports.
That's not far from me, AA County off 100 and 97. We are hoping to get Juturna back open by Spring. Matt got the law changed already, so the big challenge is over. Now it is just a matter of some construction and personality issues (the usual). Vis is beautiful for freshwater there most times. There are some other spots we're scouting and possibly some trips in the Bay for divers who are capable of handling the conditions.

 

[scrane]

If you get a couple of these you can quickly relocate your weights without undoing webbing. The quick attach tabs are very secure.
Quick-Attach Single Weight Pocket — XS Scuba - Everything For The Perfect Dive