I purchased a 3mm suit, was it a mistake

[Tribal]

yea bud your insult didnt fly over my head.... wanna dive sometime?

a SEMI DRY means attached hood and front zip normally with an extra flap to inhibit water flow.

It wasn’t an insult.

The hood and front zip aren’t needed to have a semi dry, it’s all about the seals that restrict water flow.

So a 5mm semi dry is a lot warmer then a 5mm where the water flows true.
About the layers, a lot of new divers start wet over here. A 7/8 or whatever semi dry is not enough in the winter and many people have to use a 5mm shorty on top of that.

 

[Vitesse2l]

You can't dictate other folks comfort and cold tolerance. Guide them maybe, but they need to work it out for themselves.

5mm Semi dry and 3mm hooded shortie works for me below 57f ish. Above that I drop the shortie. Others in my club are drysuit all year. Contrary, isn't it?

 

[MaxE]

All this cold water talk is making me laugh. The OP is talking about the Gulf of Mexico end of May/June. Now us local divers don’t even really call that cold, chilly maybe. Cold is our winter water temps, I’m originally from up north and I don’t know that Lake Michigan highs reach our coldest temps. The water temps that time of year in the GOM will be mid 70’s to low 80’s. Discussion of semi dry 8/9 is absurd.

 

[Addicted2H2O]

Discussion

All this cold water talk is making me laugh. The OP is talking about the Gulf of Mexico end of May/June. Now us local divers don’t even really call that cold, chilly maybe. Cold is our winter water temps, I’m originally from up north and I don’t know that Lake Michigan highs reach our coldest temps. The water temps that time of year in the GOM will be mid 70’s to low 80’s. Discussion of semi dry 8/9 is absurd.

I agree completely. Not that I know anything about your local temps up north, but I dove the GOM in late December 2017. I was fine in a full 5mm with low 60's water temps at 75fsw. Semi dry's and dry suits? Unless you are built like a 2x4 and weight 90 lbs, anything above a 5mm is asinine.

OP....try this. When you go on that trip rent a 5mm to take with you on the boat. Make your first dive in the 3mm you bought and if you're cold during, then switch to the 5mm for any subsequent dives. I know that doesn't really answer your question about whether or not you made a mistake buying a 3mm, but I think you're already got the answer to that question. You can dive it just about anywhere and be quite comfortable on top of having a good bit of abrasion protection. But the only way you're going to know for sure if it's right for the conditions you're asking about.....is to dive it yourself and see. Bottom line.

 

[scubadada]

...I dove the GOM in late December 2017. I was fine in a full 5mm with low 60's water temps at 75fsw. Semi dry's and dry suits? Unless you are built like a 2x4 and weight 90 lbs, anything above a 5mm is asinine...

I dive year round in Florida, high 60s to low 80s. I dive my full 7 mm when the water temp is low 70s or below. I often add my hooded vest. I guess that makes me an a$$, but a toasty warm one. Four dives a day, close to 5 hours, really takes the heat out of you. I have a great boat coat too

Interesting how some folks can make such broad generalizations

 

[tbone1004]

you are a top expert here in my opinion so ok. BUT! I dont think people should use a 3 mil for cold water. What you suggest MAY work but its not optimal and I think you know that. who wants to wear a 3 mil and a hooded vest....TWO WETSUITS when a flexible 7 mil is better?

tbone i know you know way more than me but please tell me why i should layer my wetsuits? i have a 3 a 7 and a 8/7 semidry..... are you saying i should use your method OR are you saying a person with a 3 mil should just go your route to save money.

how much money are they saving? a cheap 7 mil vs adding a hooded vest ....


man i dont know you need a LOT more convincing to change my opinion I THINK you are wrong

mid 60's is anything but cold, but here goes.
If you need a hood, a hooded vest gives you an extra 3-5mm around your core and minimizes water intrusion around your core. It is a significant increase in warmth compared to going "up" to the next thickness in wetsuit.
In your situation with a 3/7/semidry, I would have suggested skipping the 7mm and used a hooded vest with your 3mm. Total warmth is increased, total flexibility is increased because your limbs are free, and while your arms and legs may get a bit chilly, your total heat loss will be lower which is ideal.
I don't typically recommend layering with semidry's because they typically don't flex that much and should fit snug enough that you can't get a hooded vest underneath it.

 

[johndiver999]

Hooded vests can work very well when worn on the outside of the suit. It looks funny, but if the underlying wetsuit has a good, smooth rubber neck seal, it is often more comfortable to allow the neck seal to work as intended (against your skin) and just wear the hooded vest over top. It is more practical with a one-piece suit.

 

[NAUI Wowie]

Lol. I was down in Key Largo the middle of January. The locals thought I had a screw loose diving in a 3mm at 74-76*.

It's all about perspective. Two weeks earlier, I did a 46* dive in Virginia in a 5mm. 74* felt toasty to me.

thin long people with little body fat will go into hypothermia with a 5mil wetsuit in 46 degrees. Please anyone reading this if you are thin do not try doing this.

 

[NAUI Wowie]

Another vote for having a hooded vest in your exposure protection arsenal.

I (5'6", 160#) dive a 5mm semi-dry and a sleeveless hooded vest (both from Probe - an Australian company) in my local waters (Sydney) from about 60-80F. At the top end of that range I probably don't need the vest, and at the bottom end I'm getting uncomfortably cool at the end of the dive.

Have only done one dive below 60F - we thumbed it after 20 minutes. Above 80F (eg. Great Barrier Reef or South East Asia) I'm in a 3mm but sometimes still with the vest (sometimes I'll leave the hood pulled back).

Based on conversations with other people I'm middle of the road when it comes to feeling the cold. You'll start to get a sense of where you sit so you can adjust what people tell you to what you need.

I dont understand your setup. You have a hooded vest AND a semiddry? A semidry wetsuit means built in hood and flaps under the zipper..... You wear two hoods?

 

[Barnaby'sDad]

thin long people with little body fat will go into hypothermia with a 5mil wetsuit in 46 degrees. Please anyone reading this if you are thin do not try doing this.

It was a 20 minute fun dive in 30’ of water in a local quarry on New Year’s Day. All body types were there and most were diving wet in 5mm. All (myself included) were cold, but no one appeared to have any issues.

I’m a big guy and I would have been shivering at 60’ at 46* in a 5mm (I tried it once and won’t do it again).