Choosing the right thickness

[Cosmographer]

Although I expect to dive in tropical waters (maybe 75-80 degrees?) I still tend to get pretty cold, especially when I hit thermoclimes. I was thinking 5mm would seem appropriate. But then I came across a 2 piece farmer john style that I really like, but the suit only comes in 7mm. Considering that this would probably mean 14mm around the core, would this suit be too warm and restrictive?

[al248005]

I would be to warm in 75-80 degree water with a 7mm farmer john. Anything over 75 and I'm in a 3mm. Beware though if you do decide to go with this suit, you will need a good bit more weight to become neutral.

[Insta-Gator]

A 5mm jumpsuit (one piece) will keep you warmer than a 7mm farmer john. Also, you will be vastly more comfortable in the single layer of the jumpsuit. The weight you will have to carry while wearing 14mm over your core will be very uncomfortable.

Again, this is all my opinion.

[dumpsterDiver]

a 5mm jumpsuit (one piece) will keep you warmer than a 7mm farmer john. Also, you will be vastly more comfortable in the single layer of the jumpsuit. The weight you will have to carry while wearing 14mm over your core will be very uncomfortable.

Again, this is all my opinion.

not.

[Cosmographer]

I would definitely prefer something warmer than a 3mm suit. That's what I was wearing in the Seychelles and Mauritius last month, and I got pretty cold. I just really like the ease of putting on the farmer john type suits. The rentals I've been using are so tedious to put on and take off. So I guess I need to look for a 5mm single suit or a 3mm or 5mm farmer john. Thanks for the input!

[Cosmographer]

Actually, has anyone tried to mismatch a suit? Say, a 7mm jacket with 3mm johns?

[diveprof]

A good fitting 5 mm full suit should be fine for the temps described. You could also get a 2-3mm vest or a hood (or hooded vest) to add warmth without having to add much additional weight like you would need to do with a 2 piece.

[Dirty-Dog]

Exposure protection is entirely a matter of personal tolerances. Off Cozumel in Dec. 2011, with water temps around 80, I was wearing a dive skin and was plenty warm. In the Cenotes, with water temps in the mid-70's, I wore a 3/2 full with hood and was plenty warm. For the same 80 degree dives off Cozumel, my wife wore a 5mm full, and added a hood, booties and gloves for the cenotes.

Fit also plays a huge role. If your wetsuit is too loose, it will allow quite a lot of water to flow between the suit and your skin, and thus will not keep you warm. You might very well feel colder in a poorly fitting 5mm than in a properly fitting 3mm.

The head is very vascular, and as a result it's a huge heat sink. If you get cold easily, add a hood. On our first cenote dives, my wife felt cold even in a 5mm full plus a 5mm jacket. I bought her a hood, and now she's warm in just the 5mm full plus the hood, booties and gloves. If the hood doesn't do it, consider a hooded vest. If you're still cold, then it's time to consider a heavier wetsuit, one of the battery powered core warmers, or a dry suit.

As mentioned, the more wetsuit you wear, the more weight you'll need. But don't skimp on thermal protection just to decrease the weight you're carrying. Just keep it in mind when you're planning.