How heavy should my back plate be?

[cool_hardware52]

Hey all! I'm currently using a scuba pro knighthawk BCD + 4-5lbs of weights (total). I'm thinking of switching to a back plate system however, I'm unsure if I should get a 4lbs stainless steel back plate or an aluminum one.

Ideally, I don't want to add weights anymore.


Thanks in advance

As others have stated your current BC is likely about 3-4 lbs positive, it's inherently buoyant due to foam padding.

Once you switch to a wing, that has no inherent buoyancy, you will need very little total ballast.

A Kydex or aluminum plate and harness is likely to provide all the ballast you need, a stainless plate would over weight you.

Tobin

 

[OldNSalty]

Hey all! I'm currently using a scuba pro knighthawk BCD + 4-5lbs of weights (total). I'm thinking of switching to a back plate system however, I'm unsure if I should get a 4lbs stainless steel back plate or an aluminum one.

Ideally, I don't want to add weights anymore.


Thanks in advance

Are you using any type of wetsuit? That might add to the equation. I am in the same boat. I need 5 1/2 pounds with a traditional BC/no wet suit and I want to move to a BP/W. Assuming that 2 pounds of lead is for the BC now, I need a 3 1/2 pound plate?

I could be all wrong

 

[cool_hardware52]

Are you using any type of wetsuit? That might add to the equation. I am in the same boat. I need 5 1/2 pounds with a traditional BC/no wet suit and I want to move to a BP/W. Assuming that 2 pounds of lead is for the BC now, I need a 3 1/2 pound plate?

I could be all wrong

What you might be is missing is the inherent buoyancy of the jacket BC.

Take your current bc and empty the bladder. Throw it in the pool and see how much lead you need to sink it.

This is ballast you won't need when you leave it behind.

Tobin

 

[redacted]

Are you using any type of wetsuit? That might add to the equation. I am in the same boat. I need 5 1/2 pounds with a traditional BC/no wet suit and I want to move to a BP/W. Assuming that 2 pounds of lead is for the BC now, I need a 3 1/2 pound plate?

I could be all wrong

The tank is also a major variable in the equation. If your BP is based on an Al 80, a steel tank may tilt the cart.

 

[TSandM]

In Hawaii's salt water, with a full 3 mm suit, my 5 lb SS plate is very slightly light, so I add 2 lbs on the cambands. This is something which is pretty easy to do, using Trident or XS Scuba weight pockets.

If you are using 5 lbs of weight with your Knighthawk, you probably need about 2 lbs to sink everything except your BC. (My husband's Balance was about 2.5 - 3 lbs positive.) So using an aluminum plate and adding a little weight to it might be a good solution for you.

 

[rstofer]

Once again, I'm going to recommend ditchable weight. The fact that you CAN eliminate weights by using a SS backplate doesn't mean you should.

It would be nice to be able to become buoyant at the surface without the wing. Ditchable weight is the way to do this. It's easy to accomplish for cold water divers. It is a lot more difficult when you only need a couple of pounds while diving in warm water. One way to help is to not use highly negative steel tanks.

I'm in the minority on this. There are a lot of warm water divers that don't have ditchable weight. I wish I was a warm water diver again...

Richard

 

[walke121]

I agree with rstofer. I don't like the idea of diving with out weights. A lot of people do it but I'm just not a fan. Nothing wrong with not using them its just a personal choice.I have a knighthawk and feel that weight in the pockets makes controlling buoyancy much easier. I have 2 steel 130's (singles) and when I dive with those I don't need weights but I still use 6 lbs or so. It just helps me out with my trim.

 

[cool_hardware52]

Most humans are near neutral in their birthday suit, they make us out of water after all.

We wear ballast primarily to offset the buoyancy of our exposure suit. Thick suits need lots of ballast, thin suits less.

In warm water with no suit or a thin dive skin it's entirely possible that the only ballast is going to be the divers "rig" i.e. cylinder, regulator, BC or backplate. Anything else just over weights the diver.

In these cases there's nothing left to ditch other than the rig. Careful component selection can reduce or perhaps eliminate the over weighting issue, but when you start with a neutral human and add no buoyant suit you have few options.

Adding a few unneeded lbs just to have something to drop is beyond pointless.

OTOH, in cold water in a wetsuit I'm a big believer in configuring at least 4 lbs as easily ditchable.

It's necessary to understand each application, what the risks are and how to best mitigate them.

Tobin

 

[AbyssalPlains]

I normally dive in a tropical environment and use a 3mm wet suit. Sometimes I also use a 7mm suit but not that often.

I found that i needed no additional weight in a 3mm with my 4.7 Lbs steel plate and a 100 cu ft alu cylinder. Assuming that your weight requirements are similar, you might enjoy the steel plate because you don't have to bother with any additional weight. If you prefer to have ditchable weight, though, the answer would be an aluminum plate.

 

[halocline]

Eric (ZKY) just made a run of SS freedom plates that are about 4 lbs negative, maybe a little less. That might be perfect for you. Those plates are only for single tanks, but I suspect that's what you're talking about.

If you're diving with AL80s, you need 4 lbs to offset the buoyancy of the empty tank. If you are using an AL80 and wearing a 3 mil suit, I can't imagine you needing much less than 10 lbs ballast to offset both. Your reg and other gear might provide a couple of lbs, maybe you're a sinker by a couple of lbs, who knows.

Did you say you currently dive with a knighthawk and AL80 and 3 mil suit with 4 or 5 lbs lead? And you're not light with an empty tank? Because right away you have more than 4 or 5 lbs in buoyancy between the empty tank and wetsuit, that still leaves the inherent positive buoyancy of the BC which must be a couple of lbs at least. So, I don't know where your ballast is coming from unless it's you.

Can we please get off this nutty "must have ditchable weight at all times" nonsense?