Drysuit Weight Estimates

[RobPNW]

I received a new drysuit and other equipment and I was able to do equipment and suit checks in the local pool. I figured out an adequate weight and trim in the pool with all my normal equipment, my drysuit, dry gloves and a very basic base layer underneath. I'm hoping someone can give me some advice on extra weight needs when I get in a real world seawater environment.

I would be going from pool water to saltwater and adding a medium loft jumpsuit underneath, and wool dry glove liners and socks. Everything else would be the same. I realize everyone's body is different from the standpoint of weight, buoyancy, trim etc. I don't need a raw weight estimate from ground zero. I already have a baseline in pool water, with all my equipment, and with minimal undergarments. All I need is a rough estimate for what I would need to ADD to my baseline.

I am medium athletic build, 170 pounds and about 5' 8" tall. Any guess how much more weight I more need going to saltwater, and adding a medium loft undergarment jumpsuit, wool socks and wool dry glove liners? I assume when I get in the real world seawater with all this new gear, I will likely have to spend half my first tank, figuring out my raw weight, trim, buoyancy etc. But it would be nice to hear anyone's guess as to how much more weight to bring to the dive site as a starting point.

Thanks in advance for any advice,
Rob

 

[rsingler]

Optimal Buoyancy Computer

Set it up so it matches your current requirement, then change to salt water and look at the field for your liner and compare.


12-16#

 

[RobPNW]

Thanks for sharing that information. I'll take a look at it and see what the difference is between the estimate and what I used in the pool. I may just go back to the pool, suck it up for about 10 minutes, put all my undergarments on, and see how much weight I need to sink. Just thinking about it, all I really need to do is hold weight in my hands until I sink. I don't need to hassle with the actual weight system. I didn't put all my undergarments on because I sweat just walking around the pool without a suit on . If I do that, I can simply calculate the fresh water to sea water change which should be a lot easier. Then when I get to the real world dive site, I can spend my time figuring out my trim and weight placement around my body instead of figuring it all out. But what you posted is useful info to get me started. Take care, Rob.

 

[Landau]

Dry suit weighting is more art than science. Expect to spend a few dives before you have it nailed.

More air in the suit = more warmth = more weight, but it also means more difficultly maintaining buoyancy since you have more gas to expand and compress.

As a rough guess of how much weight you’ll need for a garment see how small a volume you can squeeze it down to. 1 litre of volume needs about 1 kg of weight. Or 1 quart needs about 2 pounds. My Fourth element fleece vest squeezes down to about the size of a 2 litre milk jug and I need about 4 lbs = 2 kg more weight when I dive with it.

 

[Bert van den Berg]

I'm totally guessing 2kg. This is based on my personal experience (and my wife's).

 

[KenGordon]

Thanks for sharing that information. I'll take a look at it and see what the difference is between the estimate and what I used in the pool. I may just go back to the pool, suck it up for about 10 minutes, put all my undergarments on, and see how much weight I need to sink. Just thinking about it, all I really need to do is hold weight in my hands until I sink. I don't need to hassle with the actual weight system. I didn't put all my undergarments on because I sweat just walking around the pool without a suit on . If I do that, I can simply calculate the fresh water to sea water change which should be a lot easier. Then when I get to the real world dive site, I can spend my time figuring out my trim and weight placement around my body instead of figuring it all out. But what you posted is useful info to get me started. Take care, Rob.

Do get in the pool with the undersuit. Undersuits make a big difference, I have three and there can be a 4kg difference between them. While messing about at a pool may seem a hassle and uncomfortable it is better than wasting time on a boat getting out and adding weight or discovering you are light at the end of a dive. Alternatively go to a quarry where you have easy access to the water and can faff about.

For the sea add 3% of your total mass. So your weight, the weight of your kit and all the lead. This is typically 3 or 4kg extra.

 

[happy-diver]

What are you all doing mixing medicines
Pools and quarries, you can't be serious

Take twice as much extra weight as you calculate and go diving

 

[lexvil]

Have you dove a 7mm wet suit?, as stated previously it depends on the thickness of the undergarments and your personal tolerance for squeeze. Squeeze makes you colder, once you get it set up in the fresh water pool you will need to add 3% or so to adjust for salt.