7mm vs. 3mm Suit

[mccabejc]

Anyone know the approximate difference in weight requirements for a 3mm vs. a 7mm wetsuit? I'm going on vacation in a couple of weeks, and will have to rent a 3mm suit and figure out my weights.

 

[The Kraken]

Mac,
Without knowing exactly the setup of what you've been diving, I'll hazard a guess.
In salt water the difference in my weight requirements between a 6.5mm farmer john/jacket, hood and gloves and a 3mm full suit, hood and gloves is about 14 pounds.
I'm 5'7", 160#.

 

[Ann Marie]

Jim,

It also matter if you currently use a steel tank or not. In December, I went to the Carribean and shed my 7mm for a 3mm. Since I dive with steel tanks here, but had to use rental tanks there, I actually needed to add 2 pounds.

 

[mossym]

i dive 28lbs with a fully 7mm, and a 7mm vest over that, in a full 3mm i dive 14lbs, so kraken's numbers are right on..thats all with al80's..

 

[miketsp]

Ah, the beauty of the metric system...
Adult body area is approx 2 sq m so for each 1mm of coverage you need about 2kg.
So 4mm difference = 8kg difference.

May be less if your 7mm wetsuit has been compressed down after a lot of diving or bad storage.
A little less if you are maintaining the same boots, gloves, hood etc as you normally use as this reduces the 2 sq m area.

 

[molksmith]

Hey this is a little of side topic but
Which suit is a better buy...
7mm or 3mm. Obviously for very warm water a 3mm suit works but I want to buy a suit and I wanted one that I could use in more places ala red sea, mediterranean, caribbean...etc...

 

[pasley]

Hey this is a little of side topic but
Which suit is a better buy...
7mm or 3mm. Obviously for very warm water a 3mm suit works but I want to buy a suit and I wanted one that I could use in more places ala red sea, mediterranean, caribbean...etc...

In thermal protection one size does NOT fit all.

In Southern California, a 7mm is necessary for our 54-60F degree waters.

In 80F degree water, you would definatly be on the warm side. So for the warmer waters a 3 mm suit or even a danskin would do.

 

[pasley]

Anyone know the approximate difference in weight requirements for a 3mm vs. a 7mm wetsuit? I'm going on vacation in a couple of weeks, and will have to rent a 3mm suit and figure out my weights.

Step one: weigh the wetsuit.
Step two: figure 2-3 pounds of lead for each pound of neoprean wetsuit.

Typical weights for average (what ever that is) male diver in full wetsuit:
7mm wetsuit 14-20 pounds of buoyancy = 14-20 pounds of lead
3mm wetsuit 6-9 pounds of buoyancy = 6-9 pounds of lead

Add to the above weight for your tank buoyancy characteristics and of course your, ahem, personal buoyancy.

Looks to me like if you are diving the same type of tank, cutting your weights in 1/2 would get you near right, and maybe a tad heavy, but not too much so.

 

[menemsha43]

I just took a 5MM diving in waters that were 75 - 80 (because there is a thermocline typically). It was pretty toasty but not uncomfortable. I would go with a 3MM for those temperatures but a 5MM is pretty versatile for a range of diving.

Also, I used 14 pounds with my 5MM suit.

 

[Tassie_Rohan]

7mm semidry: 18 lb
full 3mm suit: 9 lb

so around 9 lb difference.