BP&W Questions: weights and effect on backplate and wing selections

[dstrain]

Hi All,

I've decided to make the switch over to a BP&W setup and had a few questions regarding weighting. I got back into diving this summer after a few years off. After about 30 dives in freshwater and saltwater, I've decided I need to streamline more and a BP&W rig sounds like the best solution. After reading a bunch on the forum I would still like to throw out a few questions. Here's some info about me first that might help you guys to give more specific answers:

Me: 6', 190# and dropping. Plan to be around 170-175# and leaner by May 2015.
Diving style: I primarily dive 90% warm freshwater with temps ranging from around 68 - 85 degrees Fahrenheit. Salt water trips will be to warm tropical waters, maybe 1 -2 trips per yr. If water temps are above 75 degrees then I'll usually dive without a wetsuit, or maybe a 3mm depending on underwater terrain (oil rig barnacles, etc.). I'll likely wear a 5mm if temps will go below 70 degrees at any point.
Gear: Zeagle Stiletto BC, Zeagle regs, OMS Slipstream fins, 3mm and 5mm wetsuits, 3mm boots and gloves, 2 DRS shorty 1k flashlights, 1 safety sausage, small knife, emt shears. 100% of my diving has so far been on AL80 rental tanks, but I do plan on buying a steel 95 from a buddy.

Questions:

Weighting and backplate selection: In freshwater without a wetsuit I can sink with a full AL80 without any additional weight. With a 5mm suit I can sink with 8lbs, maybe even 6. In saltwater without a wetsuit I can sink with 8lbs, and 12lbs easily sunk me with a 3mm on. In all scenarios I had no issue with safety stops at 15ft.

The above said, and assuming I'll be doing local dives with a steel 95 tank next season, would I be better off going with a SS backplate or an AL one?

Weighting and wing selection: I tried using the wing calculator linked to on this forum, but not 100% sure I was doing it right or understand exactly its results. My total weight for statically buoyant gear (backplate, flashlights, other accessories, etc.) was -11lbs and based on using the HP95 steel tank and no wetsuit, it looks like it calculated my needed lift to be 22.6lbs. So does that mean a wing with at least that rating is the minimum I should get? Would the DRS 28lb BP/W setup be a good option then as it provides a little extra headroom?

I just want to get the most appropriate setup to cover my diving style, without having to carry extra weights, and without resulting in me having to always inflate and/or deflate my BCD sub-surface to get comfortably neutral.

Looking forward to your advice.

Thanks!

 

[Jim Lapenta]

Send me your email. I have an article on BPW's that covers most of your questions. It is too large to post or PM. As far as steel vs aluminum if you are going to dive fresh and saltwater with any kind of exposure protection I'd recommend a steel plate. A steel plate is going to allow you to take roughly 6 lbs off your belt. That you can sink a full 80 without a suit means that you'll likely not need any additional weight with a steel plate when that tank swings to 4lbs positive as it gets down to 500 psi or so. Subtract 6 lbs from the lead you need with your other configurations as well.
Wing size is a function of what you need to float your gear and in my classes also what you want to have should you need to assist another diver. Is that 6lb margin enough or would you rather have ten? Given that a 30-35 lb wing is going to be enough to allow you to assist most anyone except the guy who is diving double 95's and needs you to keep him up when his wing and suit have failed. In that case you'll need your knife or shears to cut his gear off as much as the wing. The 28 should be enough if you have some little bit of additional buoyancy from a suit or your own bioprene.

 

[Dr. Lecter]

SS plate is going to be more versatile and is the way to go unless you've got to have the 4lb difference for some bizzaro travel weight limit. And there's probably an easier way to lose 4lbs from your luggage.

Given what you report in terms of height/weight, intended diving, and weighting...anywhere around 30lbs should be fine. You don't want to go too light or much bigger than you need, but it's not necessary to make an exact science out of wing selection. If you'd like to hear someone make an exact science out of it, call Tobin at Deep Sea Supply.

As an aside, wing lift is going to be more or less irrelevant to you "sub-surface" - the wing calculator is trying to find out how much lift you need to keep a fully loaded you head-out-of-water at the surface should things go sideways. Underwater, a single tank diver with your weighting isn't going to need much at all to get neutral.

 

[decompression]

Up until you mentioned the steel 95 I would of said SS back plate but with that tank id go with an AL backplate. A 28-30 lb wing would be acceptable. In this case is recommend having a look at the Alpha/delta wing by unified team diving. It's a 37 lb wing that can be compressed to a very streamlined 20lb wing. I use them in cold water and warm.

 

[GDI]

I would suggest getting the SS BP as mentioned you will be able to drop weight. I would further consider going to the Zeagle BP. You mentioned you had a Zeagle Stiletto BCD. The bladder from that BCD should be at 35 lbs lift and is directly transferable to the Zeagle BP and so are the tank bands. You would save money on buying a new BP and wing, PLus if you needed to add additional weight for when you wear that 5mm suit in salt water (even with the steel 95) the Zeagle BP can accept a couple of different weight system options. Having that 6 lbs off the waist and displaced over the back helps on the trim.

If you are worried/concerned about tank wobble using the BP direct against the tank. no worries there is a simple solution to that as well. I Have helped many divers rig up using this and other systems , Just a consideration

 

[dumpsterDiver]

There is no way I would want a steel plate for diving with a steel tank in warm water with no wetsuit. You will probably need zero weight with an aluminum plate and a thin suit. A steel plate is just going to make you excessively heavy and if you have a BC failure, then you may have a problem.

 

[Dr. Lecter]

If 4lbs difference causes you to have a problem, you were grossly overweighted long before the SS plate came into the picture.

 

[decompression]

As the OP stated, 90% diving is fresh water and no wetsuit.....and a steel 95....the AL plate gives better options to add weights when travelling and using a 3mm suit. When diving at home (fresh, no suit) just a couple of lbs (ditchable) would be easier to dial in than starting with -6 plate, -4 tank.


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[dstrain]

Send me your email. I have an article on BPW's that covers most of your questions. It is too large to post or PM. As far as steel vs aluminum if you are going to dive fresh and saltwater with any kind of exposure protection I'd recommend a steel plate. A steel plate is going to allow you to take roughly 6 lbs off your belt. That you can sink a full 80 without a suit means that you'll likely not need any additional weight with a steel plate when that tank swings to 4lbs positive as it gets down to 500 psi or so. Subtract 6 lbs from the lead you need with your other configurations as well.
Wing size is a function of what you need to float your gear and in my classes also what you want to have should you need to assist another diver. Is that 6lb margin enough or would you rather have ten? Given that a 30-35 lb wing is going to be enough to allow you to assist most anyone except the guy who is diving double 95's and needs you to keep him up when his wing and suit have failed. In that case you'll need your knife or shears to cut his gear off as much as the wing. The 28 should be enough if you have some little bit of additional buoyancy from a suit or your own bioprene.

Thanks Jim. PM has been sent with my email address. I did want to mention that when diving without any exposure protection, and an AL80 at 500psi or even down to 100psi, I can still remain submerged without having to kick down to stay under. Not sure how much of a difference that makes as far as recommendations go, but figured I'd mention it.

 

[Dive Right In Scuba 2]

Many have already posted some good advice here. I would say that the wing lift you're looking at is about right for your needs. Of course the debate regarding steel v. aluminum BP will be ongoing, and in your case both would seem to work just fine. Just bear in mind that if you're like many BP/W users out there you will eventually own multiple back plates. My personal opinion would be that a SS BP may be the best initial "swiss army knife" option for you as it will add a mere 4lb of ballast which isn't unmanageable in those situations where you dive "skins" but would add the ability to be able to use in those situations where you find yourself diving in a location where an Aluminum tank and a thicker exposure suit is your option.