Question Figuring out weight and trim

Please register or login

Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.

Benefits of registering include

  • Ability to post and comment on topics and discussions.
  • A Free photo gallery to share your dive photos with the world.
  • You can make this box go away

Joining is quick and easy. Log in or Register now!

It's unclear to me how you can be neutral/slightly negative with no air in your BC at both the beginning and end of your dive if you've used 5 or so pounds of air during the dive. .
I can explain that to you from my perspective.
I wear a 7mm two piece suit with hood gloves booties.
The water I dive in averages 50 degrees farenheit.
The cooling action of the water makes the bubbles in the neoprene smaller therefore less buoyant, and the compression factor at depth adds to the decrease in buoyancy also. The suit doesn’t retract as fast as even a slow ascent so even at the safety stop it is not fully reformed. Those two factors about equal the loss in weight from the air supply.
Just trade one for the other.
 
Here are some comments on your weighting at present.

According to my size, I should need more weight than you. I have instructed in pool sessions wearing both a 3mm shorty and a 3mm full suit, and wearing either wetsuit will increase my weighting needs compared to you. As an instructor, I wanted to be a little overweighted so that I could sink quickly if needed or stabilize a student if needed, so that is even more weight.

With the shorty, I used 6 pounds. With the full suit, I used 8. If I were looking for perfect weight in a 3mm shorty in freshwater, I would not use any weight.

I once had a student come to me fo the OW portion of his class. We would be diving in freshwater with 7mm suits. Anticipating that, he had insisted on doing his pool sessions (different instructor) with a 7mm suit so that he would have his weighting perfectly dialed in for the OW dives. Based on that, he insisted he needed 22 pounds. By the time his OW dives were done, he was diving with 10 pounds, and he was thrilled with the revelation of how much easier it was to dive that way.
 
Thank you all for the advice and comments.

@grantctobin thanks for the links, really helped.

I had another pool session this morning, just shorts and rash guard again. After playing around I was comfortable and able to stay neutral and level with just my breathing and only 6lbs weight!!!! :) 2lbs in each droppable pouch and 1lb in each trim pocket - no weight belt. Thanks to all your advice and tips.

Very much appreciated. :cheers:
 
Assuming you were neutral with a nearly empty tank, you'll probably need 7lbs with the same outfit in seawater, which makes sense because I used 9lbs in a shorty in tropical water and 10lbs in a 3mm full suit.
 
Assuming you were neutral with a nearly empty tank, you'll probably need 7lbs with the same outfit in seawater, which makes sense because I used 9lbs in a shorty in tropical water and 10lbs in a 3mm full suit.
No being in salt water will require almost double the amount of lead being used in the pool by the OP.
 
Yeah you're right. That still seems overweighted for just wearing swim gear.
Just wearing swim gear in a freshwater pool, I would not need any weight myself.
 
Thank you all for the advice and comments.

@grantctobin thanks for the links, really helped.

I had another pool session this morning, just shorts and rash guard again. After playing around I was comfortable and able to stay neutral and level with just my breathing and only 6lbs weight!!!! :) 2lbs in each droppable pouch and 1lb in each trim pocket - no weight belt. Thanks to all your advice and tips.

Very much appreciated. :cheers:
As you get more hours in the water you will still drop from here. If you plan on doing more than one dive a day in Hawaii in November, you most likely will want a full 3mm and at your current weight use, somewhere around 10 to 12lb.

In salt I use 5-6lb with a full 3mm and I am close to your sizing (bit more weight..fatter) but use only backplates.
Yeah you're right. That still seems overweighted for just wearing swim gear.
More than likely..It is, but most feel that more weight is needed at the start. I just dove with someone that I know was at least 6lb heavy but still felt they almost didn't have enough.
 
At a pool session I had a lot of trouble trying to get buoyant, I could stay level with my fins on the pool floor, but off the floor I either sank flat or lifted up head first/ feet heavy. A little about me; Male, about 200lbs, 6ft and in the pool was wearing shorts, rash guard with Scuba Pro Go travel fins. BCD was from the shop, not mine. I had 16lbs of weight on a belt (which I think was too much), 2lbs in each dump-able pocket and a 1lb weight in non-dump-able pockets. I did dump the dump-able weights but still could not get level.

Is this too much weight? What should I try with weight distribution next time?
Yep. Definitely sounds like too much weight. I'm close to you in size. Same height, a little lighter than you.

I don't dive much in freshwater, so not exactly sure what my weighting would be there. In most of my diving situations, I'm using a steel tank, so need less than with an AL tank.

However, I do dive fairly regularly at a marine hospital/aquarium. On those dives, I overweight on purpose as it's easier to perform cleaning tasks while being a bit more planted. With a 3mil full wetsuit I generally carry about 17 or 18 lbs. You've got more than that in freshwater with no wetsuit. I'd be shocked if that wasn't too much weight.
 
https://www.shearwater.com/products/peregrine/

Back
Top Bottom