Considerations around switching to a BP/W

[divad]

@rombre, I think you are overthinking this and paralyzing yourself by trying to look at too many options.

This is an hilarious kettle-to-pot post...or is it pot to kettle...In any case, "people of earth, hello".

 

[randpchi]

Evad. Yep!

 

[stuartv]

This is an hilarious kettle-to-pot post...or is it pot to kettle...In any case, "people of earth, hello".

LOL Guilty. (and well-qualified to recognize over-thinking)

 

[Aotus]

Have you looked at the new XDEEP zen? 37lbs of lift, but designed to be super streamlined and low profile. Might be the lift you need and none of the negatives of the bigger wing in warm water.

 

[Colliam7]

Please forget backplate and wing for single tank diving in the UK unless you like having the the piss taken out of you. It's a pose. You can trim fine in pretty much any decent BCD. If you are serious about diving in the UK, you will really need a drysuit and something like a Buddy Commando bcd by AP Diving.

I am intrigued by this post. More so after visiting the AP Diving website, and looking at the AP Commando (formerly Buddy Commando). Certainly, I am in no position to disagree, or agree for that matter, having no UK diving experience. What is it about this particular BCD, or this particular type of BCD, that makes it uniquely useful for UK diving, or drysuit diving? And, what is it about a BP/W that makes it particularly unsuitable for UK diving, or drysuit diving?

 

[halocline]

I would suggest to the OP that you just get the DSS rig you want, but with a LCD 30lb wing instead of the 20. That should provide enough lift for any single tank diving you'll do. You won't notice much difference diving between the 20 and 30; the 30 is a few inches longer. It still vents very easily and is nicely streamlined. Many divers would hardly notice a difference.

Although it is theoretically possible to lose every single pound of buoyancy in a thick wetsuit, in reality you would rarely if ever be in that position. The reason is simple; a very thick wetsuit means you are diving in very cold water, and as you descend and the suit compresses, you will be getting colder all the time. It's unlikely that you could stand diving in water that cold with all the air compressed out of the suit, as the trapped air is the thermal protection.

 

[rombre]

Have you looked at the new XDEEP zen? 37lbs of lift, but designed to be super streamlined and low profile. Might be the lift you need and none of the negatives of the bigger wing in warm water.

What is so special about the Zen - compared to another ~35lbs wing?

I would suggest to the OP that you just get the DSS rig you want, but with a LCD 30lb wing instead of the 20. That should provide enough lift for any single tank diving you'll do. You won't notice much difference diving between the 20 and 30; the 30 is a few inches longer. It still vents very easily and is nicely streamlined. Many divers would hardly notice a difference.

Although it is theoretically possible to lose every single pound of buoyancy in a thick wetsuit, in reality you would rarely if ever be in that position. The reason is simple; a very thick wetsuit means you are diving in very cold water, and as you descend and the suit compresses, you will be getting colder all the time. It's unlikely that you could stand diving in water that cold with all the air compressed out of the suit, as the trapped air is the thermal protection.

Thank you, that's interesting. A total loss of buoyancy could happen with a drysuit though, couldn't it? In which case the 30 lbs might not be enough?

 

[cool_hardware52]

I would suggest to the OP that you just get the DSS rig you want, but with a LCD 30lb wing instead of the 20. That should provide enough lift for any single tank diving you'll do. You won't notice much difference diving between the 20 and 30; the 30 is a few inches longer. It still vents very easily and is nicely streamlined. Many divers would hardly notice a difference.

Although it is theoretically possible to lose every single pound of buoyancy in a thick wetsuit, in reality you would rarely if ever be in that position. The reason is simple; a very thick wetsuit means you are diving in very cold water, and as you descend and the suit compresses, you will be getting colder all the time. It's unlikely that you could stand diving in water that cold with all the air compressed out of the suit, as the trapped air is the thermal protection.

I disagree. One could plan a dive in cold water in wetsuit with no intent of going deep, and yet find that either they had unintentionally exceeded their planned depth or had an emergency that required going deep.

One has to go fairly deep to zero out a wetsuit, I can't find the source right now but if IIRC a study of neoprene required 180-190 fsw for a suit to reach the point where no further compression was possible.

But...... before one takes much comfort in that depth it is worthwhile to remember that *most* of the change in buoyancy of a wetsuit happens shallow, because of the % change in total pressures are greatest near the top of the water column.

At the surface the suit is subject to 1 ATA.

At 33 ft that pressure has doubles to 2 ATA, i.e. the pressure has doubled

At 99ft it's 4 ATA. i.e. the pressure is 4 x that of the surface

At 180 it's ~6.45 x and the change from 100 to 180 is only about 1.6

(This BTW is why you should try to get as close as possible to your MOD before your tech instructor evaluates your ability to hold + or - *1* foot of depth )

Tobin

 

[halocline]

At some point, if a wetsuit does lose every bit of its buoyancy, you could conceivably carry one in a mesh bag to some depth, let the bag go, and it would continue to sink. I bet that is possible, but from my limited experience with very thick wetsuits in cold water I know that it gets really freaking cold really freaking fast as depth increases. Aside from an unintentional, uncontrolled descent, I just don't see any diver tolerating the level of exposure that would result from losing even a slight majority of the suit's thickness. For example, start out with a 7mil farmer john (14mil on the core), go to 99 ft, and you are now essentially wearing less than a 5/3. How's that going to feel in 40F water?

Your usual advice about determining a wetsuit's total buoyancy and using that figure in calculating lift needs is good (and of course you have a LOT of experience in this), but I suspect in the case of really cold water and really thick suits it provides a bit of a margin in terms of actual minimum lift needed for safe and comfortable diving.

 

[halocline]

Thank you, that's interesting. A total loss of buoyancy could happen with a drysuit though, couldn't it? In which case the 30 lbs might not be enough?

Sure, it could happen. But one thing that's different about a completely flooded drysuit is that it won't expand in the same way that a wetsuit will as you ascend. So you could easily drop some weights and swim up.

So much of the required lift conversation is really about being properly weighted to begin with. Typically the only properly weighted divers that really NEED a lot of lift are technical divers carrying multiple extra tanks and lots of gear. Those divers are often quite negative at the beginning of a dive. Redundant lift is the norm, because a loss (for example a burst OPV or big hole in the BC bladder) can be really dangerous.

But single tank, recreational diving is fundamentally different. You're not carrying any excess gear, and you can usually swim towards the surface with little or no additional lift. You only need lift to compensate for wetsuit compression and the weight of the gas you use. Maybe there are divers that really need more than 30 lbs for that, but it's pretty unusual.