wet suit v dry suit bouyancy difference

[mad major]

Off to Sharm in November. All my diving over the last few years has been in a drysuit. i have a 5mm full wetsuit for the sharm trip and want to know is there a quick way of calculating the weight i will need when i switch from drysuit to wetsuit?
major

[John N]

To be honest your best bet is to tell the dive centre what you are wearing and they will usually estimate weight required very accurately.

Then just do a weight check on the first dive.

I normally use a couple of kilos less in a 5mm than my drysuit but it is heavily dependent on what sort of equipment you use.

[TonyG]

Major
Here are the PADI guidlines
Peak Performance Buoyancy

Basic Guidelines:
Exposure Suit Type Begin With
1. Swimsuit or dive skin 0.5 - 2 kg/1 - 4 lb.
2. Thin (3 mm/1/16 inch), one-piece 5% of your body weight
wet suits – shorties or jump suits
3. Medium-thickness (5mm/3/16 inch), 10% of your body weight
Two-piece wet suit
4. Cold-water (7mm/1/4 inch), two-piece 10% of your body weight,
wet suit with hood and boots plus 1.5 - 3 kg/3 - 5 lb.
5. Neoprene dry suits 10% of your body weight,
plus 3 - 5 kg/7 - 10 lb.
6. Shell-style dry suits* (using light-weight, 10% of your body weight,
nonfoam underwear) plus 1.5 - 3 kg/3 - 5 lb.
7. Shell style dry suits* (using heavy-weight 10% of your body weight,
or foam underwear) plus 3 - 7 kg/7 - 14 lb.
* Regarding shell-style drysuits – the lead needed beyond 10% of your body weight is
primarily determined by the buoyancy of your underwear. The buoyancy of different
underwear types varies greatly.
Conversion Estimates for Salt or Fresh Water
Convert from salt water to fresh water (or vice versa) using the following estimates.
Amount of Weight to Add
(Fresh Water to Salt Water) or
Body Weight Subtract (Salt Water to Fresh Water)
45 - 56 kg/100 - 125 lb. 2 kg/4 lb.
57 - 70 kg/126 - 155 lb. 2.3 kg/5 lb.
71 - 85 kg/156 - 186 lb. 3 kg/6 lb.
86 - 99 kg/187 - 217 lb. 3.2 kg/7 lb.
Depending on the type of tank you use, it can become 1-2 kg/3-5 lb. more
buoyant by the end of your dive. The popular 80 cubic foot/12 litre tank
will become approximately 2 kg/5 lb. more buoyant. To compensate for this
increased buoyancy near the end of your dive, you may need to add some
weight beyond the basic guidelines above. Additional weight, beyond the
guidelines may not be needed for some types of steel tanks.
Using
Regards
Tony

[Mark Davies]

Do you really need to know?

The dive operator will be supplying your weights and the first dive you do out there will include a weight check to get your bouyancy right. There are so many variables (such as what tanks you'll be using) it just isn't worth worrying about until you get out there.

They will probably give you too much, so each dive drop a little bit until you get it right. You should have it sorted by the end of the first day.