Steel or Aluminium back plate?

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hansonl

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Messages
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Location
River Falls, WI
# of dives
500 - 999
I am looking at getting a back plate and wing and trying to get the pros and cons of aluminium and steel, which is better and why, and peoples opinion on them, Thanks.
 
Welcome to the board.

This is one of those occasions where, in the absence of additional information such as are you diving warm ocean, tropics, cold ocean, great lakes, wearing wetsuits, drysuits, etc., its difficult to provide any more detailed answer regarding what might work best for you given your specific circumstances.

The short response is that you select a plate depending on how much weight you need, and where you need it.

Steel plates put 6 lbs (or 8, 10, 12, 14, etc.) flat against your back relatively close to your Center of Gravity (COG). If you trim out well that way, great.

If not, you may need to go with an aluminum plate (1.4 lbs or so) and a weightbelt.

Your body is like a lever, and your COG is the fulcrum. The rest of your weight (tanks, regs, fins, etc.) determines where you'll need to locate additional lead to allow you to trim out horizontally. Wearing a weightbelt takes weight from your back and puts it further out along your "lever". You'd do this, for example, if you were continually doing headstands in your new rig.

So, you pick a plate based on your needs.

In turn, your needs depend on all those other environmental characteristics and equipment factors. If you need additional input, we'll need some additional information.

Hope this helps, and again, welcome to ScubaBoard.

Doc
 
Does the aluminum affect you positively like aluminum tanks?
 
:confused:

Not sure I understand your query, but basically no - it doesn't.

Aluminum tanks can screw with your weighting due to their swing weight - as you empty the tank, it gets lighter and lighter. (The swing in a Luxfer 80 cu ft tank is something over 4 lbs or so, may be slightly different for a Catalina)

So you need to weight yourself with your aluminum tank nearly empty, to ensure you can hold safety stops with a very light tank (e.g. at the very end of the dive).

Plates never vary in weight.

An aluminum plate will always weigh ~1.4 lbs (may be slightly more or less depending on manufacturer).

There are also polymer plates that basically don't weigh anything at all in the water, if you need to go this way. They basically neither add weight nor subtract it for your weighting purposes.

Was that the question you were getting at?
 
It will also depend on the tanks you are diving. That's why it's better to purchase a system rather than individual components.

Ultimately, you may end up with several plates and wings depending on the type of diving you are doing.
 
Right, for recreational single tank diving with a steel tank and a 3mm shorty, I use an aluminum backplate (and a much smaller single tank wing).

When I need to use a dry suit or thick wet with much more bouyancy, I use a stainless steel backplate and a V weight even with double steel tanks as while they are very negative when full, they are still near neutral when empty and I want to be sure that I can still stay neutral at the last deco stop.

As Doc indicates you need to have just a enough weight to stay neutral at 10' with no air in the suit and/or BC/Wing when all your tanks are near empty (the point where you will have maximum positive bouyancy.) A steel plate makes no sense if you are still 5 lbs negative at the end of the dive with a given tank and suit configuration - the extra weight then just makes you excessively negative at the beginning of the dive whena ll your tanks are full (the point where you are most negative).

In addition, the uneeded extra weight has to be compensated for through out the dive which means extra air in the BC oir wing and the resulting larger bubble of air expands and contracts more making precise bouyancy control more labor intensive.

Once total weight is determined you need to address trim. That depends on the plate, the tank, the fins, etc and can get pretty complicated so it becomes mostly a trial and error process with a few general rules. For example, shorter tanks tend to work better for shorter people than taller tanks.

Aluminum plates are less expensive by about $100 than a SS plate and if you are going to be doing recreational diving with weight pouches an aluminum or ABS plastic plate makes sense as you can always add weight to the pouches, use a V weight, tail weight, etc, but you cannot make an stainless steel plate lighter if you are over weighted.

Deep Sea Supply offers another option with additional stainless steel weights that bolt to your plate and that may be another option to consider if you don't own a plate yet.

Eventually, you will probably own an aluminum plate as well as a ss plate.
 
Steel for local diving, aluminium for travelling.
 
I am looking at getting a back plate and wing and trying to get the pros and cons of aluminium and steel, which is better and why, and peoples opinion on them, Thanks.

Hanson,

You have received a lot of very good advice here already. Without more specific information about your application all we can do is speculate.

Having said that I'll make a couple of assumptions and look at what is a very common set of applications.

I'm assuming that you are new to BP&W's, and will be diving single tanks.
Further I'll assume that like many you are diving in moderate to cold water at home, and travel to warmer locations.

For cold water single tank diving you will almost certainly benefit from a Ballast that SS plate provides. Commonly our users will dive with a SS plate, and a Steel cylinder in their local colder water.

For travel many assume that a lightweight plate, al or plastic is the obvious first choice. I disagree. If you look at the typical travel diver they are using AL tanks, and thin exposure suits. They need about 8-10 lbs of ballast. A SS plate and harness provides about 6lbs and a reg provides about 2 lbs. Often this means they can dive without a belt.

If you use a lightweight plate in the tropics you will have a buoyant tank and neutral or near neutral plate on your back, and 4-6 lbs in a belt, this can make horizontal trim more difficult.

If you dive more at home, buy a SS plate (and appropriate wing for cold water) Take this gear on your next warm water trip and see if it suits you. Most find that it does.

Remember the travel weight savings from a al plate to a SS plate is about 3 lbs.

Let me know if I can answer any other BP&W questions you might have.

Tobin
 

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