Red Sea diving, how much extra weight do you need?

[Lucianagogogo]

I'm diving in Red Sea Dahab, the Guide insisted to give me 6 kg of weight! (5mm wetsuit).

Though I mentioned I dove in Mediterranean Sea with 4kg of weight only and wearing 5mm wetsuit. Even that it was slightly heavy for me!

I'm not a pro so I just listened the guide in the end.

Obviously I felt too heavy today when dived so will reduce 1kg tmr.

I understand the Red Sea is saltier you perhaps need more weight to go down. But how much more you need it?

 

[Jai Bar]

Both the Mediterranean are among the most salty bodies of water. As with any large body of water, it is not necessarily constant in either depth or location.

That said, the salinity in north red sea is about 39-41 g/kg, and med sea is 35-39 g/kg, such a large range of differences is not so straight forward to know exactly how much weight difference you will need not really knowing for sure the exact salinity differences, moreover if you are not diving with the exact equipment and tank?

Most divers need 1-2 kg adjustment between med-red sea, but best is to check your buyancy at the end of the first dive. Not that it will make a big difference whether you add 1 or 2 kg, personally I hate taking extra weight (got enough of that on my own body ), so I always test. Especially since the weights in Egyptian boats (and in the markets) are not so very accurately measured...

 

[Lorenzoid]

Here's a previous discussion I recall. There may be others.

Salt - impact on weights?

Hi - just got back from a dive trip in Hurghada. I was very surprised with how much weight I needed to use ( an extra 4 kg!). One of the dive guides mentioned the Red Sea had more salt and this was common... anyone else have a similar experience?

scubaboard.com

 

[inquis]

Without knowing the rest of your gear, it's difficult to say whether 6 kg is a lot or a little. (It would be fine for me & my gear, for instance, in *average* salinity waters.) However, based on density estimates of the Red Sea, I would need little less than 1 additional kilo for the Red Sea. I expect that is a reasonable bound for the increase you would need from your Mediterranean weighting.

Best bet is what you did: go with the DM's advice and adjust based on a proper weight check at the end of the 1st dive.

 

[pisauron]

Both the Mediterranean are among the most salty bodies of water. As with any large body of water, it is not necessarily constant in either depth or location.

That said, the salinity in north red sea is about 39-41 g/kg, and med sea is 35-39 g/kg, such a large range of differences is not so straight forward to know exactly how much weight difference you will need not really knowing for sure the exact salinity differences, moreover if you are not diving with the exact equipment and tank?

Most divers need 1-2 kg adjustment between med-red sea, but best is to check your buyancy at the end of the first dive. Not that it will make a big difference whether you add 1 or 2 kg, personally I hate taking extra weight (got enough of that on my own body ), so I always test. Especially since the weights in Egyptian boats (and in the markets) are not so very accurately measured...

Strange calculation.
If the salinity is 41
And in the med it's 35

And you add 1kg when moving in between. So it's 1kg for ~5 salinity.

Then when diving in a fresh water lake with 5 salinity you will need just 1kg (2lbs) and ideally remove 30 salinity which is 6kg (13lbs)

And that's just with the most conservative calculations. If it actually 2kg for 41-39 difference it becomes much more funny.

And yes, it's linear.
And yes, it's a myth.

מליחות המים וכמות המשקולות | אמיר גור

ש××רת ××ת×ס ש×× ×× ×××ת ××שק×××ת ×××¢×ר ×צ×××× ××× ×ª×××× ××××ת ××××פ×, ×¢×§× ×©×× ×× ××××××ת ×× ×××

amirgur.com

 

[Jai Bar]

Strange calculation.
If the salinity is 41
And in the med it's 35

And you add 1kg when moving in between. So it's 1kg for ~5 salinity.

Then when diving in a fresh water lake with 5 salinity you will need just 1kg (2lbs) and ideally remove 30 salinity which is 6kg (13lbs)

And that's just with the most conservative calculations. If it actually 2kg for 41-39 difference it becomes much more funny.

And yes, it's linear.
And yes, it's a myth.

מליחות המים וכמות המשקולות | אמיר גור

ש××רת ××ת×ס ש×× ×× ×××ת ××שק×××ת ×××¢×ר ×צ×××× ××× ×ª×××× ××××ת ××××פ×, ×¢×§× ×©×× ×× ××××××ת ×× ×××

amirgur.com

Strange calculation.
If the salinity is 41
And in the med it's 35

And you add 1kg when moving in between. So it's 1kg for ~5 salinity.

Then when diving in a fresh water lake with 5 salinity you will need just 1kg (2lbs) and ideally remove 30 salinity which is 6kg (13lbs)

And that's just with the most conservative calculations. If it actually 2kg for 41-39 difference it becomes much more funny.

And yes, it's linear.
And yes, it's a myth.

מליחות המים וכמות המשקולות | אמיר גור

ש××רת ××ת×ס ש×× ×× ×××ת ××שק×××ת ×××¢×ר ×צ×××× ××× ×ª×××× ××××ת ××××פ×, ×¢×§× ×©×× ×× ××××××ת ×× ×××

amirgur.com

The calculation is simple enough- Archimedes' principle. It is simple if you know all the details, which most of us don't l: exact differences between salinity (or water's specific gravity), the volume of water that you displace, including equipment. This is very different for each individual, and some places the Mediterranean is 35ppt, other 38ppt. Red Sea can vary as well from 38-41 ppt, so too many variables to know exactly how much.

For some it results in 1kg difference, others 2kg. It is actually better to just adjust your weights in the check dive, that is not so difficult to do.

 

[Altamira]

In November 2023, I used the same weight in pounds converted to kilos in Safaga (Red Sea) as I did in Seychelles, Zanzibar and the Caribbean. I am probably a pound or two heavy in the Caribbean, but that's where I like to be, but I did not notice any issues at the safety stops in the other locations, especially in the Red Sea. I never checked/asked about the salinity at Seychelles or Zanzibar.

 

[tridacna]

Strange calculation.
If the salinity is 41
And in the med it's 35

And you add 1kg when moving in between. So it's 1kg for ~5 salinity.

Then when diving in a fresh water lake with 5 salinity you will need just 1kg (2lbs) and ideally remove 30 salinity which is 6kg (13lbs)

And that's just with the most conservative calculations. If it actually 2kg for 41-39 difference it becomes much more funny.

And yes, it's linear.
And yes, it's a myth.

מליחות המים וכמות המשקולות | אמיר גור

ש××רת ××ת×ס ש×× ×× ×××ת ××שק×××ת ×××¢×ר ×צ×××× ××× ×ª×××× ××××ת ××××פ×, ×¢×§× ×©×× ×× ××××××ת ×× ×××

amirgur.com

אבל לא צריך להיות דוקטור לפיסיקה או מדען אטום איראני

 

[pisauron]

אבל לא צריך להיות דוקטור לפיסיקה או מדען אטום איראני

Don't tell the Iranians we got people claiming you add weights when going to the Red Sea, they will stop taking us seriously.

Truth is the change is salinity is so minor you can use the same weights.

 

[tridacna]

Don't tell the Iranians we got people claiming you add weights when going to the Red Sea, they will stop taking us seriously.

Truth is the change is salinity is so minor you can use the same weights.

I used to travel with a salinity refractometer to every destination. Despite minor changes of salinity, I never ever changed my weights. The salinity changes are so small that they never required any modification in bouyancy.

I think this myth has been propagated by DMs who want to make sure that their customers take enough weights on each dive. I remember an op in Bermuda that claimed that their seawater was the saltiest in the Caribbean and to “add 4lbs to compensate”. That’s when I began to take my refractometer on trips.