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JugglingMonkeys
12-04-2007, 04:45
I dove at the Florida Keys a month or so ago - with 10 lbs using a full 3 ml wetsuit. It was just right.

Then I was in the Red Sea two weeks ago - with a 5 ml shorty - and needed 10 kg, about 22 lbs!

They said it's because the Red Sea is "more salty."

How much will I need on the Great Barrier Reef in Australia - with a full 3 ml suit? Anyone have an idea about the "salt variation" there?

Thanks

BouzoukiJoe A.K.A. wrecker130 AKA Chuck Norris AKA joeforbroke (banned)
12-04-2007, 09:06
That huge difference must be due to the different gear config and not the difference in the salt/mineral content.

All gear affects buoyancy. Changing exposure suits, tanks, BCs, accessories, etc. all affect the amount of lead you need to carry. You might want to keep a log of the gear you are wearing, whether it's salt water or fresh water, and the amount of lead you need. Then you might use this to estimate the amount of lead.

If you use your own gear and keep good notes I think you'll find that you can get pretty close every time. If you rent it's much harder since you can't know how buoyant the gear is.

Puffer Fish
12-04-2007, 09:34
I dove at the Florida Keys a month or so ago - with 10 lbs using a full 3 ml wetsuit. It was just right.

Then I was in the Red Sea two weeks ago - with a 5 ml shorty - and needed 10 kg, about 22 lbs!

They said it's because the Red Sea is "more salty."

How much will I need on the Great Barrier Reef in Australia - with a full 3 ml suit? Anyone have an idea about the "salt variation" there?

Thanks
I'm sure it will come as no surprize, that the level of salt varies... there is a web site (could not find easily) that details this... however, as far as the ocean goes... the difference between the keys and the Great Barrier Reef should be trivial... but there are other things to watch for (like type of tank being used).

As to trapped bodies of water... all bets are off. Same goes for diving in shallow water areas, or areas were there is a large river runoff.

CaptainRon
12-05-2007, 13:50
Does anyone have a "rule of thumb" for increasing weight when going from fresh water to saltwater (Warm Caribbean)? Myself and my kids have gotten or weight setup down in freshwater. We will be using the same equipment and wet suits during our trip to Cozumel and I was wondering about how much extra weight we will need.

BouzoukiJoe A.K.A. wrecker130 AKA Chuck Norris AKA joeforbroke (banned)
12-05-2007, 14:51
Does anyone have a "rule of thumb" for increasing weight when going from fresh water to saltwater (Warm Caribbean)? Myself and my kids have gotten or weight setup down in freshwater. We will be using the same equipment and wet suits during our trip to Cozumel and I was wondering about how much extra weight we will need.


I use this table to make an estimate.

Weight ------- change
100-125 lb --- 4 lb
126-155 lb --- 5 lb
156-186 lb --- 6 lb
187-217 lb --- 7 lb

dannybot
12-05-2007, 18:29
There is a chart on p. 213 of the PADI AOW book "Adventures in Diving", but it doesn't differentiate well on the different kinds of wetsuits, just a general guideline. I find it helpful for a starting place when I travel, to save time trimming out.

There is no mention of the different salinity of water, but there are significant variances. I saw a show on Discovery channel where they found an "underwater lake," whose water density was so great, the sub filming could not sink!

navyhmc
12-05-2007, 19:30
FWIW, you are correct, different bodies of water have different salinity. The Pershian Gluf had the highest that I cold tell-took me 12 lbs to get neutral w/o any gear on. The pacific was ther least-diving Lajolla took only 8 and the two dives were within a month of each other.

Without giving out secret info, our subs actually take incremental salinity tests in the water they're in to find the best water to hide in and best water to hunt it.

I saw that same special on the underwater lake. If I recall, it was in the Gulf of Mexico at about 3000' and it literally looked like plants/trees on a beach.

JugglingMonkeys
12-06-2007, 06:25
Here's a link for the formulas to adjust weights:

http://forum.scubatoys.com/bcs-buoyancy-compensators-stab-jackets/3613-weights-salt-water.html

Thanks for the comments re the salt variations! I'm going to assume that GBR and Keys are about the same.

CaptainRon
12-06-2007, 11:25
Thanks for the link. That helps, although I'm going to get my son to write me a little computer program using Larry's formula so I can get all these numbers out of my head.:smiley29:

CompuDude
12-06-2007, 12:33
Does anyone have a "rule of thumb" for increasing weight when going from fresh water to saltwater (Warm Caribbean)? Myself and my kids have gotten or weight setup down in freshwater. We will be using the same equipment and wet suits during our trip to Cozumel and I was wondering about how much extra weight we will need.


I use this table to make an estimate.

Weight ------- change
100-125 lb --- 4 lb
126-155 lb --- 5 lb
156-186 lb --- 6 lb
187-217 lb --- 7 lb

Pretty good.

With normal-size people, I generally just tell them 4-6 pounds and it covers the majority of people out there.

A proper weight check is a handy thing to do, regardless of math, however, if it's possible to arrange one.