BP: Aluminum or SS?

So, I convinced my LDS to put a BP/W into rental so I could try one out last weekend on a trip to West Palm Beach. It was a basic Hog Al BP + 32# Wing + Basic harness. I ended up really liking it and have decided to get my own BP/W setup.

I understand the math behind wing size, buoyancy, and so on but I don't have the experience that many people on here do so I'm asking opinions on an aluminum versus a SS backplate. I live in Florida and most (if not all) of my diving will be warm water, though having said that I would say that I tend to wear a little more exposure protection than many people in warm water (last summer in the Keys I was using a Cressi 2.5mm full suit and was perfectly comfortable, I use up to 7mm full suit + hood in the winter and in the springs).

Adding to the dilemma is that I own steel tanks but many times on trips end up having to use AL80's from time to time (as if I dive multiple boat trips in a single day they often don't have time to fill my steel tanks, and this summer I'm going to Bonaire and will most likely use AL80's there from what I understand).

I'm leaning towards getting a SS backplate. Even with my steel tanks I still needed a few pounds of weight with the aluminum backplate using a 5mm full suit + hood so I'm thinking the SS plate is the way to go.

William

William,

I'd suggest having enough ditchable weight to be within a pound or two of neutral at the heaviest point in your dive. That will be at max depth with a weightsuit. A 5 mm wetsuit, steel tank, and ss backplate sounds like just about zero weight to ditch to get neutral. That is OK, if it is your case. Do try dumping your wing at the max depth you think you will ever be at, and swimming yourself up. If it is not easy try going for a few pounds less with an aluminum backplate.

How much weight does it take to just sink you with a mask and a half of a full breath of air while wearing the exposure protection you describe?

Vislor
How much weight are you carrying and where with the al plate?
Is your tank riding high to trim out the weight belt??
Goint to a SS plate will allow you to dump some of your weght belt and lower the tank to trim out.
Of course you need to make these decisions based on your max suit compression.
I would start with 20 ft, al tank 500 psi, 2.5 mil suit and go for neut. Note the weight. If you need more thatn 6# go to a steel plate and add a couple of # lead on a belt. If less than 3-4# do it on a weight belt.
All beyond that will make you heavy. change of -10 for a going to a full steel tank -4 for a SS plate and an extra -15 or so for the wet suit change.
For me having the weight equal through out the SS plate is a plus., not so much on the belt and less tank movement to trim.
You dont want to get to the point that you have so much weight on a belt that you cant ditch it safely. Or your wing can not bouyancy you without putting head up. It sounds like you have a doughnut wing so you dont want much weight on a belt.
I guess i am warmer than you i use a 2-3 mm shorty for ocean and a full 3mm sometimes a farmer john in the springs when in doubles. my 3mm fj is +19 in fw so that is too much suit for a single tank for me, (bouyancy wise). Of course you could always go dry shell and eliminate the suit compression all together. I am 250# 6' and in a 3/2 shorty i use a steel plate with 8# bolted on the plate (DSS plate) using a LP95 tank in salt water. i remove the 8# bolt on weight in FW. and need no lead. The most i can go neg is about -12 with a full tank. Something to lok at also is perhaps is a lavacore full suit. Or a wet suit with seals to reduce the needed thickness.

Take all the negs and subtract the amount you can swim up and that will be the amount of lead you need on a belt. If still a lot of weight all you can change is suit.

It really depends on you and your wetsuit. I can't use steel BPs in warm water because it by it's self will overweight me. In warm fresh water I use no lead at all and only 4 lbs in salt, a 6# SS BP would overweight me in both situations...actually an AL plate will overweight me in fresh warm water. Add a steel tank to the mix and I become grossly overweighted. Also, when flying shedding the extra 4 lbs of a SS BP can make or break a weight limit. Bottom line, you can always add weight but once you have it all off you will just have to deal with being overweighted

It is pretty easy to add more weight when a light plate is not enough. It is hard to remove it from a heavy plate. My heavy plate with steel tank is too much for warm water dives. But who said you can only have one?

I agree fully i have a SS an al and a kydex

awap:

It is pretty easy to add more weight when a light plate is not enough. It is hard to remove it from a heavy plate. My heavy plate with steel tank is too much for warm water dives. But who said you can only have one?

Click to expand...

awap:

It is pretty easy to add more weight when a light plate is not enough. It is hard to remove it from a heavy plate. My heavy plate with steel tank is too much for warm water dives. But who said you can only have one?

Click to expand...

^This. An ali plate is more versatile IMO, better for traveling, using with heavy twins. I too am overweighted with a steel plate and minimal exposure protection even with an ali tank. There is only 4lb difference but if you do need to use that extra weight you can position it where it best suits your trim. Most end up with one of each anyway (I did). They come up pretty often on the used market and aren't expensive.

I guess as others have said it's down to your own personal weighting i.e. what do you carry at the moment? Winds typically reduce the weight you carry anyway. I personally dive a SS plate with a lightweight steel tank for most of the year but in the summer when I don my 3mm I dive my Ali plate - if I dive Ali cylinders when I go away then I take my SS plate. I have both rigged up with a custom harness (I have weight belt buckles on the shoulder straps so I can get out of it with ease on the surface if I need too and it makes adjusting between suit thicknesses a breeze).

The general rule is that if you are a fat, salt water diver, buy SS. If you are a skinny FW diver buy aluminum. Of course there are other factors such as AL or Steel tanks, exposure protection, etc.