Buoyancy and wet suits

Question
When diving in the Caribbean with no wet suit I could maintain good buoyancy at surface and shallow depth (35') with 8lbs, no issue.  This weekend I took the PPB class with a 7mil wetsuit in freshwater and with 30 pounds of weight I could not do a free descent (but got to 20 feet and dropped like a rock).  At 4'10" and 51 years carrying 30 pounds is not making for enjoyable dive experience.  Short of giving up any hope of local diving (by definition in water 40-70 deg F) is there something I did wrong?

Answer
Hi Sheri,

First, let me assure you that you didn't do anything "wrong"!!  As I'm sure you know, the 7-mil wetsuit is the cause of your grief.  It literally floats like a cork and you'll need lots of weight to get underwater while wearing it.  Diving in the Caribbean didn't require the wetsuit so...no problem.  The fact that you "dropped like a rock" after descending beyond 20 feet is due to the compression of the wetsuit material and it's subsequent loss of buoyancy.  You may also have had some residual air trapped under your wetsuit during your descent.  That air will also be compressed and further result in a loss of buoyancy as you descend.  

Since you took the PPB class, you've probably already discussed the techniques of proper weighting and weight distribution so I won't address any of that in this answer.

Unfortunately, you'll still need to continue to carry the extra 30 pounds while wearing the 7-mil suit but you can get creative to minimize the discomfort.  Weight can be carried in a weightbelt or in the pouches of a weight-integrated BC.  It can also be placed on the top or bottom of the tank using ankle weights around the tank valve or special weight rings which fit inside the tank boot.  There may also be trim-weight pouches attached to the tank band on your BC.  Another option is to use a special weight harness which you wear like a vest under your BC.  It holds the weights at your waistline but they are supported by the vest.  These weights can be quickly released in an emergency without having to remove the vest.  You can use various combinations of the above equipment to distribute the weight so it isn't all hanging from your waist.  One thing to keep in mind is that you MUST be able to quickly release the majority of the weight in an emergency.  Things like tank weights and trim-weight pouches cannot be dumped in an emergency so don't put more than 8-10 pounds (total) in them.

Another option is to use a steel tank instead of the more common aluminum tank.  Steel is heavier than aluminum so you don't have to wear as much lead to achieve negative buoyancy.

As you can see, Sheri, you've still got to carry the weight to sink the 7-mil suit, hood, boots and gloves but it may be a lot more comfortable for you if you can spread it around a little.

A final option would be to use a drysuit...no neoprene involved.  You would wear an insulating thermal suit under the drysuit.  Diving with a drysuit will require some specialized training since most of your buoyancy will be controlled through the addition of air to your drysuit instead of the BC.  A drysuit may be a better overall solution to your weight problem since you can probably use less weight to begin with.  It sounds like you're planning to do a lot of local cold-water diving and the drysuit would completely eliminate the initial shock of cold water running inside your wetsuit and would also be much more comfortable for an extended dive.  Just think...when you peel that suit off after the dive, you'll still be DRY!!  Check with your local dive shop to see what brands they carry and to get additional information along with proper instruction.

Sheri, I hope this answer gives you some food for thought and some good options to make your local diving much more comfortable.

Sincerely,
Mike Giles
Mike's Dive Center
mikescuba.com