Considering BP/W switch and need input

[lulubelle]

Duplicate

 

[flots am]

I disagree that all plates are plates.

Some have lots of holes around the outside (which facilitates things like placement of Argon bottle holders) and some have very few. Spacing of harness slots can vary, and some plates have camband slots and others don't. DSS plates have mounting holes for his weight plates, and elastomeric inserts in the lower slots so you don't have to use a triglide to stabilize the harness. Bend angles vary. Material quality and finish vary. And weight varies a little, too. And some manufacturers make plates in different sizes, and others don't.

I have one of Tobin's plates, and while it's very nice, these are actually all minor differences. If you need an extra hole or two to mount something, all it takes is a drill, and while the plastic slot inserts certainly keep the webbing from flapping around, I can't say that I see any significant webbing movement on my other plate that just has plain slots.

It's all just hardware.

flots.

 

[flots am]

The only problems I am trying to fix are 1)unneeded bulk and 2)the efficiency of traveling with my gear. . . . As for travel, I am aiming for smaller and lighter. I have seen how much smaller the travel bags of friends traveling with BP/Ws are and I envy that.

You'll be able to find BCs and BP/Ws that are bigger/smaller/lighter/heavier than each other. Changing from one to the other doesn't guarantee easier packing or less weight. Also, a lot of the "unneeded bulk" comes back once you start hanging off various tanks, reels and whatnot.

Again, I don't care what you dive with, however I don't think you're going to find any significant improvement in much of anything from switching.

. . . I am able to change my position easily with my breathing, can fin up without difficulty and maintain my safety stops without issue. And there is always my lift bag. I like the buoyancy characteristics of steel tanks far better and would not dive anything smaller here though I do generally board with at least half of my tank left.

I won't dive without enough ditchable weight to make me positively buoyant. Doing so makes a good deal of OW training non-functional and increases the difficulty of some rescues. However you're welcome to dive however you wish.

flots.

 

[Blue Sparkle]

I have one of Tobin's plates, and while it's very nice, these are actually all minor differences.

It's all just hardware.

It's true that some differences are "just" details (which may or may not be important to a given buyer), however plate size is more significant. Some of us don't fit the "standard" size, and not all brands come in sizes.

Another difference that may be more substantive is whether there are cam-band slots in the plate. For divers who don't plan to use an STA, lack of slots would be noticeable.

Blue Sparkle

 

[lulubelle]

I won't dive without enough ditchable weight to make me positively buoyant. Doing so makes a good deal of OW training non-functional and increases the difficulty of some rescues. However you're welcome to dive however you wish.

flots.

Not that this thread is about buoyancy, but I want to understand your point, so I'm going to try again.

Pretty much everyone who dives here would be negative, some seriously so, without the lift from their wings.

What would your recommendation be then to someone who is close to neutral with an appropriately sized tank and full wetsuit? My BC has 35 pounds of lift and I carry a lift bag. I depend on those to create positive buoyancy when needed and check their integrity and function quite often before diving. In regards to your early comment about BC failures, I've been there (dump valve stuck in open). And I am close enough to neutral that I am able to ascend easily by finning, using my breathing, and in a pinch, have plenty of bits that I could ditch in an emergency situation.

I do not like the buoyancy characteristics of aluminum tanks and will not dive anything smaller than a 100 as I dive to the edge of recreational limits. I am tall and not small so a smaller tank wouldn't suit me either. A 5mm would be great if I could find a non custom one to fit. But that's another thread.

 

[flots am]

Pretty much everyone who dives here would be negative, some seriously so, without the lift from their wings.

Yes. If properly weighted, at the beginning of the dive, on the surface, you'll be negative by whatever the gas in your cylinder weighs. At depth, you'll be negative by the weight of the gas in your cylinder and the buoyancy lost due to wetsuit compression.

What would your recommendation be then to someone who is close to neutral with an appropriately sized tank and full wetsuit?

I recommend whatever combination of plate/tank/etc. that allows you to become positively buoyant at any point in the dive, by ditching weights.

This may become important, if, for example, you jump in negative, with a thick wetsuit (which compresses and loses buoyancy as you descend) and find yourself many feet down with no air. Swimming up isn't too difficult if you're breathing, however if you're both significantly deep and OOA, you'll find yourself wishing for a way to be quickly on the surface with little effort on your part.

This scenario isn't as bizarre as it sounds and actually accounts for a number of fatalities.

I do not like the buoyancy characteristics of aluminum tanks

FWIW, AL tanks have exactly the same buoyancy change from empty to full as steel. You can compensate for the additional positive buoyancy of an AL tank with additional lead and any trim problems by moving weights around.

Note that there are divers that do not beleive in ditching weights underwater for any reason (weight ditching isn't especially useful in a cave or with a deco obligation). They have other methods of not dying, based on not making potentially fatal mistakes, and having a known-reliable well-trained buddy, and being able to handle problems underwater instead of at the surface.

flots.

 

[lulubelle]

I recommend whatever combination of plate/tank/etc. that allows you to become positively buoyant at any point in the dive, by ditching weights.

This may become important, if, for example, you jump in negative, with a thick wetsuit (which compresses and loses buoyancy as you descend) and find yourself many feet down with no air. Swimming up isn't too difficult if you're breathing, however if you're both significantly deep and OOA, you'll find yourself wishing for a way to be quickly on the surface with little effort on your part.

This scenario isn't as bizarre as it sounds and actually accounts for a number of fatalities.


flots.

I understand your point now but am pretty sure there isn't a clear solution for those of us who do not require additional weight beyond that of our tanks. I don't think that there is a combination that will allow me to become positive by ditching weights without compromising on gas planning which is far more likely to be a good way to die here.

My BC floats somewhat when empty. I couldn't possibly tolerate a thicker wetsuit in summer due to topside temps of 100 plus here. And I wouldn't choose a smaller/lighter tank as I am 1. Not a small person 2. Dive routinely to the edge of recreational depths 3. Must carry adequate air to assist an OOA buddy at those depths at the end of a dive.

So I guess I will have to remain content with making sure that my wing is in good working order so that I can use that lift if needed, carrying a lift bag so that I can use that to lift whatever needs to be lifted to the surface, and picking good buddies.

And we see plenty of people who find all sorts of ways to die here in NC, so point well taken.

Anyway, back to the topic of BP/W selection. Guess the steel BP is out then

 

[cool_hardware52]

Yes. If properly weighted, at the beginning of the dive, on the surface, you'll be negative by whatever the gas in your cylinder weighs. At depth, you'll be negative by the weight of the gas in your cylinder and the buoyancy lost due to wetsuit compression.

Not necessary or desirable to be negative by the weight of you gas if diving single cylinders in thick wetsuits or buoyant drysuits. The real goal is to be able to hold a shallow stop with near empty cylinders. Doing so just increase problems the diver need deal with in the event of a buoyancy failure.

Wetsuits and undergarments both compress. A thick wetsuit that might be 20-24 lbs positive at the surface at 1 ATA will easily loose 5-6-7+ lbs at 15 ft, 1.5 ata.

I recommend whatever combination of plate/tank/etc. that allows you to become positively buoyant at any point in the dive, by ditching weights.

What combo would that be for swim trunks and an al 80 in warm water?


Tobin

 

[flots am]

What combo would that be for swim trunks and an al 80 in warm water?

I don't dive anywhere without exposure protection, so you'll need to ask someone else.

flots.

 

[flots am]

Not necessary or desirable to be negative by the weight of you gas if diving single cylinders in thick wetsuits or buoyant drysuits. The real goal is to be able to hold a shallow stop with near empty cylinders.

How exactly do you manage to be neutral at the end of the dive without being negative at the beginning of the dive?

flots.