Question Weight problem: how come?

[Maartnn3293]

Hi divers

I am a new diver, got my Open Water last month and did my first fun dive in the ocean yesterday.

During my training I wore a 7mm wetsuit in fresh water and had 4kg of weight. This worked fine for me.
Yesterday I did my first fun dive in the ocean (shallow dive) where I also wore a 7mm wetsuit and started with 6kg. After doing the weight check, I added 2kg to have 8kg in total. After adding, I was not able yet to descend, so the guide pulled me down and added another 1kg that made a total of 9kg. This worked while underwater.

My question: is it normal to use 5kg more in salt weather then in fresh water? I am 1m85 but I am skinny with my 63kg.

Thanks a lot!

 

[James79]

A few things come into play... Part of it is that it's a percentage change in total weight (not just lead). Part of it could be comfort level (new surroundings/dive conditions lead to minor nerves, which leads to breathing "off the top" of your lungs). Best advice I would give is to check out the optimal buoyancy calculator here; Info - Optimal Buoyancy Computer
I tend to work it sort of backwards, plugging in knowns to deduce unknowns. Once you have it set up correctly for you, it does a pretty solid job of predicting weighting requirements for gear and condition changes.

Respectfully,

James

 

[scubadada]

Hi @Maartnn3293

Did you do a weight check at the end of your dive, near reserve pressure in your tank, no air in your BC, neutral or near neutral at your safety stop?

Other than weighting, there are other reasons divers sometimes have trouble descending, air in BC, air trapped in wetsuit, failure to exhale. In general, you start a dive overweighted by at least the weight of gas you will consume on the dive. It depends on the cylinder, but you're talking about 2-3 kg. It does seem like you had to add an inordinate amount of weight for your dive in saltwater. I would have thought more like 2-3 kg.

I'm heavier than you, 83 kg, and use the same weight as you did in saltwater wearing a full 7 mm and a 5/3 mm hooded vest.

 

[TravisD]

It takes as much as it takes. That said - I find that if it's been a while since I've been in the ocean that I sometimes need a little more lead until I relax. Also, was everything else completely identical? Different/newer suit, different cylinder, etc will chane thing. Did you add a hood/gloves?

 

[Rilelen]

If everything else is exactly the same, I find on average that experienced divers need to add about four pounds going from fresh to saltwater.

That will be more if people are uncomfortable or stressed (ocean, boat, and waves tend to make for more stressful entries than a calm lake shore entry) and unconsciously kicking or holding air in their lungs.

It also doesn’t take into account other changes - for instance did you use the same type of tank on both dives? A steel tank in freshwater and aluminum in salt could easily cause the discrepancy you experienced.

 

[Maartnn3293]

Thank you all for the reactions, tips and tricks. I can say I was a bit nervous performing the dive since it was my first dive since I am an Open Water Diver. First time in the ocean and first boat dive. First time abroad.

Best advice I would give is to check out the optimal buoyancy calculator here; Info - Optimal Buoyancy Computer

Thank you for the advice to check out the calculator. I will do it definitely when back home from holiday as it works better on my computer than on my phone.

Did you do a weight check at the end of your dive, near reserve pressure in your tank, no air in your BC, neutral or near neutral at your safety stop?

I didn’t do a weight check at the end of the dive, but during the safety stop (and the rest of the dive) I did not have buoyancy problems. I am not sure if I had no air in my BCD or just a little bit. Definitely something I have to check very well during my next dive.

Also, was everything else completely identical? Different/newer suit, different cylinder, etc will chane thing. Did you add a hood/gloves?

It also doesn’t take into account other changes - for instance did you use the same type of tank on both dives? A steel tank in freshwater and aluminum in salt could easily cause the discrepancy you experienced.

During my training I used a Mares Rover 7mm suit and during my local dive here I used the same brand and size, but this suit here seemed newer than during my training. During my training I used a 10 liter steel tank, during my dive here a 12 liter aluminium tank. I added boots as well. So these things meight effect my added weight as well I guess.

 

[Wibble]

Steel vs aluminium cylinder will account for the difference alongside unfamiliarity.

 

[Rilelen]

Yep, the switch from steel to aluminum is it. Steel tanks are more negatively buoyant - if you switch from steel to aluminum, you will need to add lead.

 

[KenE]

Anxiety will naturally cause you to hold more air in your lungs. As divers we fight this natural urge on a regular basis. Try to learn to start your descent with a large exhale. This helps is a couple ways, first it tends to help get the descent started, second as you descend the first meter or so you will naturally take a breath, this breath will help slow the descent which will start to increase because equipment is compressing becoming less buoyant. I tend to wait an extra minute before descent to breath and bring my lung volume down and calm the nerves. I also take an extra second or two at the bottom of descent to sort out anxiety, usually will adjust my weight belt or clear my mask, or anything just to give my mind time to adjust to the new environment. I find this helps with gas consumption and lung management.

Weight is highly dependent on individual and equipment. Once you find the right amount for you, then just adjust accordingly for the equipment changes you make. The calculator helps with these adjustments. Don't listen to anyone who says that is way too much or way to little, they don't know and can't know how buoyant your body is, some take more, some take way more, some don't take any (hard headed). It is what it is for each individual. As your wetsuit ages you will be able to drop a pound or two, if you get a new wetsuit you might need to add a pound or two.

 

[Maartnn3293]

Anxiety will naturally cause you to hold more air in your lungs. As divers we fight this natural urge on a regular basis. Try to learn to start your descent with a large exhale. This helps is a couple ways, first it tends to help get the descent started, second as you descend the first meter or so you will naturally take a breath, this breath will help slow the descent which will start to increase because equipment is compressing becoming less buoyant. I tend to wait an extra minute before descent to breath and bring my lung volume down and calm the nerves. I also take an extra second or two at the bottom of descent to sort out anxiety, usually will adjust my weight belt or clear my mask, or anything just to give my mind time to adjust to the new environment. I find this helps with gas consumption and lung management.

Weight is highly dependent on individual and equipment. Once you find the right amount for you, then just adjust accordingly for the equipment changes you make. The calculator helps with these adjustments. Don't listen to anyone who says that is way too much or way to little, they don't know and can't know how buoyant your body is, some take more, some take way more, some don't take any (hard headed). It is what it is for each individual. As your wetsuit ages you will be able to drop a pound or two, if you get a new wetsuit you might need to add a pound or two.

Thank you for the tips and tricks! I will try to use these during my next dives.