Wetsuit bouyancy information

[murdrcycle]

Is there any rating system that guages the bouyancy of wetsuits? I have figured out that some wetsuits are much more bouyant than others. I am 5'10" and 205 lbs. I use 16lbs to stay under in freshwater while wearing a 3MM full, and 18 lbs when wearing a 7mm full. I bought a 3/2 shorty for the ocean and when my tank is less than 1000 lbs at 30 ft. I can't stay under with 22 lbs in my BC while holding onto a 5 lb rock (I took it right to the surface - sorry Destin Jetties). I need a new shorty. I can't use one that puts me over the weight limits of my BC.

 

[Charlie99]

I use 16lbs to stay under in freshwater while wearing a 3MM full, and 18 lbs when wearing a 7mm full. I bought a 3/2 shorty for the ocean and when my tank is less than 1000 lbs at 30 ft. I can't stay under with 22 lbs in my BC while holding onto a 5 lb rock.

Are you sure you were using the same sort of tank in all cases?

What you report if far, far different than the norm.

My experience is that wetsuits have a buoyancy of around 2 pounds per mm of thickness, maybe 3 pounds if it is an XL size and new.

A couple other notes:
1)The freshwater to saltwater adjustment for a single tank diver of your size will be very close to 6 pounds.

2) The typical 5 pound rock will have only a pound or two of negative buoyancy, perhaps even less.

3) If you have 22 pounds of lead in a BCD and can't stay down at 30' while wearing a 3/2 shorty, then there is something definitely amiss. Things like air trapped in the BCD, and a leaking inflator slowly filling the BCD, etc.......

 

[BKP]

Absolutely agree with Charlie above. Something is amiss.
I dive a 5mm in freshwater quarries with 4lbs. TOTAL weight. To be fair, I dive an HP100, so add 6 lbs. that I'd need with a standard AL80, and that gives me a total of 10lbs. in fresh wearing more neoprene than you (and a DiveRite Transpac -- no additional backplate, or anything).

My stats are close to yours. I'm 5'9", 195lbs.

What type of a BC are you using? Some (with loads of padding, cummerbunds, etc.), add more buoyancy than you'd think. Additionally, can you have a buddy check to make sure your wing is completely deflating? Situate yourself, so your dump is at the highest possible point. If you're using a horseshoe, instead of doughnut wing, you may even have to rock back and forth a bit to bring that last bubble to your vent.

Are you carrying any other buoyant gear? Camera housings, are your fins buoyant, etc.

 

[Charlie99]

My comment about things not making sense were more in regards to the various weighting being inconsistent with each other, rather than the absolute amount.

I am 5'10" and 205 lbs. I use 16lbs to stay under in freshwater while wearing a 3MM full, and 18 lbs when wearing a 7mm full.

This implies that the 7mm full has only 2 more pounds of buoyancy than does the 3mm full. I would expect at least 6 pounds of difference, more likely 8 or more.

I bought a 3/2 shorty for the ocean and when my tank is less than 1000 lbs at 30 ft. I can't stay under with 22 lbs in my BC while holding onto a 5 lb rock

If 16 pounds works for you in freshwater, then 22 or 23 should work for your 3mm full in saltwater. Most shorties have less buoyancy than the equivalent thickness shorty, so 22 should be more than enough. Wetsuits compress at depth, with most of the compression taking place in the first 30'. That should make you even more negatively buoyant. (I'm ignoring the rock, since it has nowhere near 5 pounds negative buoyancy.)

I'm not making any judgements about the correctness of your total amount of lead, but instead am trying to explain why what you post seems internally inconsistent.

 

[murdrcycle]

Thank you all for your input. In an effort to get an answer to my question let me further clarify my situation, since it is obviously a sticking point. Yes, there are inconsistencies, and it is what is raising my concern. When I was wearing the 3mm full suit I was on my checkout dives, so they may have given me more weight than I really needed. When I wore the 7mm long the weighting was correct. My BC is a Balance back-inflate. If air is getting trapped in it, it sure is hiding well. I not only try to empty it in my inconveniently buoyant situations, I go so far as to open both the top and bottom vents, creating a nice circuit. No help.

Both the 7mm and 3mm longs were ScubaPro's that I rented from my LDS. The shorty is a $40 cheapy that I bought from LeisurePro. Even though wetsuits are the same thickness, those made by different manufacturers are certain to contain different amounts of air bubbles and probably made of different types of neoprene. Therefore, buoyancy will differ from one wetsuit to another. Which led to my original question - is there any sort of rating system (or good customer review sight, magazine comparo, etc) that gauges the buoyancy of a wetsuit?

 

[BKP]

Both the 7mm and 3mm longs were ScubaPro's that I rented from my LDS... Even though wetsuits are the same thickness, those made by different manufacturers are certain to contain different amounts of air bubbles and probably made of different types of neoprene. Therefore, buoyancy will differ from one wetsuit to another. Which led to my original question - is there any sort of rating system (or good customer review sight, magazine comparo, etc) that gauges the buoyancy of a wetsuit?

Much clearer...

First of all, when you're dealing with wetsuits, not only will buoyancy differ from manufacturer to manufacturer, but also from line to line within the same vendor, and even from one size to the next of the same model. For instance, Henderson has Insta-dry, Hyperstretch, Gold-Core, etc., all of which have different thermal and buoyancy characteristics even among the same thickness suits.

Further confusing the issue, when you RENT wetsuits, you have no idea the age or usage of that wetsuit. Neoprene generally loses its buoyancy with age and use. The more compression cycles it goes through, the faster the loss. I once rented a 5mm that had absolutely 0 buoyancy. I couldn't compress it any more if I had a hydraulic press.

Frankly, the only way I've seen of actually knowing the buoyancy of a particular suit is by weighting it down in a water column, by itself, until it begins to go negative. Even then, the buoyancy will change slightly with age...

If you happen to hear of a manufacturer that posts their buoyancy ratings for each model (and size) of their exposure suits, I'd be very interested in seeing it myself.