BCD Lift, what is Required

Hello, I am new to diving and just received my open water certification and now I want to purchase some equipment.

One of my first purchases will be a BCD, and after reading the forum I have decided that the Zeagle Stiletto might be my best option. However, when I spoke with a dive shop sales person, he mentioned that the Stiletto only has 35 pounds of lift which may not be good if diving with a full, 7mm wet suit, which I will be doing. Of course, the shop didn't carry Zeagle products.

I am a pretty big guy (losing weight finally ) and when I did my open water cert dives I used 18 pounds of weight and was wearing a 3mm half suit.

My question is should I be concerned that the Zeagle Stiletto only has 35 pounds of lift or is the store sales person only trying to get me to buy what they have in the store?

Thanks.

They are trying
35lb is way more than enough for a 7mil suit.

the type of wetsuit is not so important for this. The thicker the wetsuit, the more it floats and will need to be offset by weight. For example, going from a 3mm wetsuit to a 7mm wetsuit requires only that you add only enough weight to offset the 4mm difference in the neoprene. The wetsuit will compress a little at depth, but a 35 lb BC is more than enough to compensate for this.

The more important questions are what type of tanks you will be using? and how negative you weight yourself?. If you are using a large steel tank, you might be very overweighted without adding more weight, and 35 lbs might not be enough, but if you are using an AL80, you will probably need to add some weight.

The bottom line is that if you are weighted correctly, such as able to maintain a 3 minute safety stop with a near empty tank and little to no gas in the BC, then a 35 lb BC is plenty big enough.

I dove a Stiletto in So Cal and also dove it in the Galapagos (went to a harness for other reasons). With a 7mm wetsuit, steel 100 tank, 16lbs of lead (22-24# with an aluminum tank) it works great and has plenty of lift! I also take it to Hawaii. It travels well and is quite compact and streamlined when worn.

35# of lift with a 7mm suit should be more than enough. I dive a 32# HOG wing with steel 100's and 120's and a 7mm wetsuit and have plenty of lift.

Kristopher

35-lbs is a lot of lift.

It's all depending on how much is your dive weight and how do you plan on carrying your ballast/lead weights.

If you can, go into a swimming pool with just your wetsuit, mask, snorkel, fins and weight belt. Do weight check (with a full lungs, you should float eye level). Take note of how much weight you needed.

Then think of what sort of BC you want to use, what tank you want to use, etc. All of these equipment have their own buoyancy characteristics and they either add or subtract from the lead weight that you've determined while wearing your wetsuit alone.

Essentially you'd want a BC to be able to float itself, a full tank and whatever else on your BC (lead weight, big ass cannister light, etc.) at the surface. The wetsuit will take care of floating you.

nimoh:

the type of wetsuit is not so important for this. The thicker the wetsuit, the more it floats and will need to be offset by weight. For example, going from a 3mm wetsuit to a 7mm wetsuit requires only that you add only enough weight to offset the 4mm difference in the neoprene. The wetsuit will compress a little at depth, but a 35 lb BC is more than enough to compensate for this.

The more important questions are what type of tanks you will be using? and how negative you weight yourself?. If you are using a large steel tank, you might be very overweighted without adding more weight, and 35 lbs might not be enough, but if you are using an AL80, you will probably need to add some weight.

The bottom line is that if you are weighted correctly, such as able to maintain a 3 minute safety stop with a near empty tank and little to no gas in the BC, then a 35 lb BC is plenty big enough.

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The type (thickness) of the wetsuit is indeed quite important in the decision. Yes, the thicker the wetsuit, the more it float (more buoyant) it is. But that thickness is more gas bubbles which compress at depth and buoyancy is lost. This loss must be compensated by the BCD. I have seen 7mm wetsuits that were around 30 lb buoyant. Take it down to 130 ft and you could be looking at only 6 lb of residual buoyancy. The other 24 lb needs to be compensated for with the BCD. Then there is the weight of the gas that also requires compensation. An 80 Cu ft tank with 6 lb of gas should not be a problem. But if you consider a 120 cu ft tank then you may need 9 lb of compensation and suddenly that 35 lb bladder is starting to look a little iffy if that is the kind of diving planned. If that depth and a larger tank are not part of the plan, then 35 lb should be OK. Otherwise maybe 40 or even 45 lb of lift may be the way to go.

The lead that you carry to submerge is not directly part of the consideration unless you are over-weighted. Any excess weight also must be compensated by the BCD.

nimoh:

The more important questions are what type of tanks you will be using? and how negative you weight yourself?. If you are using a large steel tank, you might be very overweighted without adding more weight, .

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Very unlikely would anyone be negative with no lead in a single tank wearing 7mm wetsuit.

You need lift to do two things:
1) Compensate for the compression of your suit plus the weight of the gas in your tank.
2) Float your rig without you in it on the surface.

Your suit might compress and lose 20lbs or so of buoyancy, and the gas might weigh 7lbs or so. 35 lbs should easily cover that.

If you are putting weights in the weight pockets, and you exceed 30 lbs or so, you might be pushing it as far as the floating the rig goes. The easy and smart way to deal with that is to have some of the weight in the pockets and some on your body with either a weight belt or harness. This is fairly important in cold water; if by some chance you had to take your BC off at depth, and all your weight was on the BC, you'd head feet first for the surface while your rig sunk like a stone. Ideally you want both yourself and your rig to be somewhere close to neutral.

Okay, here goes, someone's gonna say it if I don't. If you're a big guy that needs lots of weight in cold water, consider getting a steel backplate with a wing instead of a soft, buoyant BC. You'll take weight off your belt and have some ballast on your back where it belongs.

halocline:

<snip>

Okay, here goes, someone's gonna say it if I don't. If you're a big guy that needs lots of weight in cold water, consider getting a steel backplate with a wing instead of a soft, buoyant BC. You'll take weight off your belt and have some ballast on your back where it belongs.

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You just described me and why I went from a Zeagle (that with more than the 35# of lift the OP has) that would barely float my gear to a BP/W system and a weight belt. I like it MUCH better and find myself using less overall weight, have better trim and much faster and easier swimming, both on top and below.

fisheater:

You just described me and why I went from a Zeagle (that with more than the 35# of lift the OP has) that would barely float my gear to a BP/W system and a weight belt. I like it MUCH better and find myself using less overall weight, have better trim and much faster and easier swimming, both on top and below.

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I went to the BPW with SS plate for a different reason: less shifting of the tank/BC combo on my body. The reduction in needed lead is a nice bonus.

And stickers!!! I can put all sorts of stickers on my SS backplate.