Ok, I watched their video. Some video critiques are below.
Seems like you need this plus a BC for the surface, depending on how low to the water you are comfortable with, given the limited buoyancy range and delay to pump in the ballast that your suit will lose at depth.
The pro is you can use water to compensate for your suit's surface puffiness and later add more to replace air weight as the dive progresses. And the system buoyancy does not vary with depth, though your suit will.
You do not need to start heavy by your air weight and suit compression weight. But past that I'm not seeing the huge weight advantage between a diver rigged with this vs the same diver with a tropics PB/W.
Plus it seems you need to be exact on your weighting, given the limited swing you have after accounting for gas loss. Vacation divers are not good at knowing their weighting.
Within those limits, interesting and could be fun. Though the same properly weighted in a tropics suit and BC doesn't pose many buoyancy issues anyway and shooting up and down in the water column is not very wise.
If we get you properly weighted in the tropics, you can use this cool system, which you don't really need at that point.
There are some pros:
- Less need to dump or cork as approach surface, particularly in no suit or a thin tropical one.
- Limits the corking force to the expansion of your wetsuit, assuming you don't dump your ballast.
- Limits the yo-yo ing at depth from diving like a sea horse to your legs getting tired, not gas expanding/contracting and you over compensating with the BC as well. Unless you dump the water ballast and have to slowly pump back up as you float up to the surface.
Some video critiques:
- In looking only at tidal volume, they are skipping residual inhalation and exhalation volumes.
- Not all BCDs require extra weight just to sink, such as a back plate, like their system uses..
- A 5' depth change does not cause anywhere near the volume (or even area) change they show in their image.
- BC
is to deal with wetsuit completion; read most any book on diving for that.
- You do not keep that neutral buoyancy at depth "even if you are diving very heavy wetsuits".
- They touch on lung control, but without saying shifting the tidal volume point up and down within the residual volumes.
- On malfunctions and diver errors:
- - Many divers will still need weights, and loss of them will have the same effect.
- - Stuck power inflator is on issue, yes.
- - They touch on the diver error of fully dumping a normal BC at depth and sinking to depth, but not of diver fully purging ballast and rising irrevocably to the surface
- "It eliminates the problem of overweighting." HOW?? For it to work, it requires that you not be overweighted. And the dive crew and experience team
might ensure that. But not the gear system itself.
About 2 lb of water for one minute of pump use.
They keep saying lighter coming out after the dive. That would seem only the buoyancy shift of your wetsuit, which is not much for the tropics.
I think it is cool within its ballast range, realizing an apparent operator error risk exists of dumping all your ballast that can only be slowly re-added. And thus rising to the surface, whether you really meant to or not.
They need to be more precise in describing it and its limits, several of their slides are visually misleading. That leaves a very bad impression.
Edited for a bit of clarity.
