Help me understand wet suits for cold water

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I hate gloves. I lived in Boston for 8 years and never wore them. I dive in somewhat warmer water than you (but still cold enough for a 7mm wetsuit, 7mm hood, 5mm booties) and went bare-handed for a while. But then I had to get a pair of gloves for an organized dive event that required them, so I bought the thinnest pair I could find--1mm. I actually wear them all the time now, because they keep my hands warm enough that I have more dexterity with them than without.

I find that most everyone has an Achilles heel when it comes to the cold--a body part that needs more insulation or you're just going to be miserable. For me, it's my ears. All those gloveless winter days I survived in New England, I still needed ear muffs. Hence the 7mm hood. Know what yours is and work around that.

One other option you didn't mention is adding a neutrally buoyant layer under your wetsuit. I have a Sharkskin jacket; Lavacore is another brand, and there are at least a couple others. You can also pour warm water into your wetsuit right before you splash; it helps a lot with that initial icy seepage.
 
The typical farmer john 2-piece is getting fairly rare these days. But it was the standard in the 80s and 90s. You get a double layer around your core. It should be warmer due to more insulation. Between fit and extra seams and another water layer it isn't as warm as it should be. But you do have the buoyancy swing as all that neoprene compresses with depth.

If all wetsuits were made with the idea of how a wetsuit should really work, there would be no such thing as a semi-dry. It would just be a correctly implemented wetsuit. Doing what it should in keeping water flow through the suit to a minimum while still being a wetsuit. Since the typical wetsuit isn't that good, the semi dry name came about as a way to claim performance closer to a drysuit without actually being one. There are some other options that also work. Henderson has the Aqualock line. There are seals at the hands, feet, and neck that when used with matching gloves, boots, and hood work to reduce the water flow through the suit. There are other versions of the same idea.

The whole wetsuit can be rendered nearly ineffective by simple mistakes. I had someone once fold the material at the back of the hood as they zipped me up. Couldn't see it. Didn't feel it. That fold made a funnel that just flushed cold water through the suit. Solved that with a hooded vest. A little extra on the core and no way to fold the neoprene at the back of the neck.

Fit is extremely important. If the fit isn't right it is the wrong suit no matter what kind of deal they are offering on it. Form fitting. Absolutely not baggy at all. Anywhere, from the wrists to the ankles.

Research you are doing is good. But internet is very broad. Take your class, see what they put you in. how does it fit? How well does it keep you warm? How well do you move around in it? But I would avoid buying right now. Add some experience points first.
 
I dive mostly cold water as do you. You are looking for advice from others so this is what I do:
in F degrees:
75F- body suit
65 and over-- shorty
60-65--7 mil farmer john top only
below 60-- full 7 mil farmer john

Hood--all the time, even if warm water for keeping water from going deep in ears

gloves: 60 & over-- reef gloves
50-60-- 5 finger gloves
below 50-- 3 finger lobster mitts.

I've found this out for ME over 15 years.
 
the performance of wetsuits depends on the amount of water circulation and the compressed thickness you are using it at. the amount of water circulation is generally smoothskin/skin-in < semi-dry < regular wetsuit, however fit matters that a well fitting suit will perform better than an ill fitting suit of a better type or design. the semidry has a bit more leeway in that the suit can be a bit ill fitting as long as the seals are snug. also, the stiffer the neoprene, the more warmth it will retain at depth by resisting compression.

if you plan on doing deeper dives, don't bother buying an expensive wetsuit. get something used or rent if needed until you get around to getting a budget drysuit like a seaskin.

for shallower diving, it really depends on whether you fit stock sizes well and if you don't mind the lubing up for the freediving suits and that they require a bit more attention due to their fragility. a semidry is a better option if you do not fit stock sizes well.
 
I dive mostly cold water as do you. You are looking for advice from others so this is what I do:
in F degrees:
75F- body suit
65 and over-- shorty
60-65--7 mil farmer john top only
below 60-- full 7 mil farmer john

Hood--all the time, even if warm water for keeping water from going deep in ears

gloves: 60 & over-- reef gloves
50-60-- 5 finger gloves
below 50-- 3 finger lobster mitts.

I've found this out for ME over 15 years.

remember, temperature is extremely personal. For me, these temperatures are crazy, and I don’t know anyone else who would dive in 65 f water in shorty. That doesn’t mean he’s wrong, it’s just different for different people.

I live in Asia, and as an American, I’m considered warm bodied. For me:

82 and above, skin
77-82 3 mm
72-77 5 mm
60-72 8 mm semi-dry

I’ve dove down to 52 in a semi-dry and was okay, but the Japanese dive shops said they wouldn’t take me below 52 (11 c) if I wasn’t diving dry, because it was a “liability”. Notice how different from what others are recommending. I don’t think diving at 50 f is a problem with a semidry. But I guess for MOST people, a 5 mm at 70 degrees will be a better choice than a shorty.
 
Also you may want to consider that cold is a factor in DCI.

It may or may not be relevant depending of the type of dives you will do (depth and time)
 
...
I will be diving mostly Lake Huron, St Clair river, and quarries In and around Sarnia Ontario Canada....

Based on that location I would not even consider a standard wet suit. I would go Semi-Dry (wet suit) at a minimum with the attached hood. And if you do so, I would strongly suggest installing a pee-valve in it. I know some will mock me but unlike a standard wet suit where you will have a curtain amount of "flushing", with a good semi-dry you will be swimming in your own pee the whole time! And a pee-valve in a semi-dry is actually easier to use than in a dry suit. You can use a much shorter hose from the condom cath to the valve.

I put one in my Aqua-lung 5/7 semi-dry and it works like a champ! They laugh until I am standing on the dive platform between dives voiding out of the valve still warm in my suit!! (most never notice the trickle down the suit anyway...)
 
Based on that location I would not even consider a standard wet suit. I would go Semi-Dry (wet suit) at a minimum with the attached hood. And if you do so, I would strongly suggest installing a pee-valve in it. I know some will mock me but unlike a standard wet suit where you will have a curtain amount of "flushing", with a good semi-dry you will be swimming in your own pee the whole time! And a pee-valve in a semi-dry is actually easier to use than in a dry suit. You can use a much shorter hose from the condom cath to the valve.

I put one in my Aqua-lung 5/7 semi-dry and it works like a champ! They laugh until I am standing on the dive platform between dives voiding out of the valve still warm in my suit!! (most never notice the trickle down the suit anyway...)
Are they not laughing because they are still climbing the platform under the trickle ?

“Um ... there is some kind of thermocline in this quarry ...”
 
I live not too far from the OP, and it looks like I frequent a lot of the same spots that they will be diving.

Locally (eg Tobermory), you will see some people wearing 7mm wetsuits on shallower dive charters/walkons. For more advanced dives, it is almost all drysuit diving. I see the occasional wetsuit on deeper (60-110ft) dives, but they are increasingly rare due to the cold water.

I used a 2pc 7mm suit fro my first ten years or so of diving, including the deeper recreational dives in Tobermory, and multiple same day dives right into November. That suit served me well for many, many dives in water temps around 40F.

I have been diving dry now since 2012 when I decided that I wanted to try ice diving (done in 2013). Haven't worn the 7mm since.

For the St Clair River, however, it gets fairly warm in the summer, and I would consider that in a 5mm or even a 3mm by late July/August/early September.

My advice? See if you can rent a 7mm wetsuit (one piece or 2pc) for training and certification if you have not done so already. See what kind of diving draws you. If you are going to be doing a lot of local cold diving (eg Tobermory, Lake Huron), I would invest in a drysuit after certification, especially if you plan to eventually move on to an advanced certification and dive our deeper wrecks.
 

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