5mm Wetsuit vs layering 3mm wetsuit with a vest/neoprene shorts etc...

[-JD-]

FWIW: As others indicated, it is individual.

I just did Blackbeards trip (Bahamas - w.t. 78deg avg.) at the end of February. I wore my Waterproof W3 full suit (it is a good 3.5mm with wrist and ankle "seals" and just a Lavacore hood (when I remembered). They recommend a 5mil for "winter", so I brought a 3/2 shorty, a Lavacore vest, and a 2mil neoprene beanie for layering - didn't need a one and never felt chilled.

 

[jwoolste]

Hi @jwoolste

Where are you going on the liveaboard, how many dives/day do you expect? What do you expect the water temp to be? What temperature are you comfortable in with your 3 mm, how many dives/day do you do.

Exposure protection and tolerance to cold are individual. I have a home in SE FL and dive a 3, 5, and 7 mm full suit +/- a 5/3 hooded vest every year to cover usual water temps of high 60s to low/mid 80s for 2-4 dives per day. I hate being cold and it increases my gas consumption. If I don't know the water temp to expect, I will often take two wetsuits with me to the boat and decide which to use based on current information from the crew. I always take the hooded vest with me for extra flexibility.

I will be diving the Red Sea on this trip, expecting 3 dives a day for 6 days. Ive never been remotely cold in my 3mm but I've also never done 3 dives a day or gone diving anywhere colder than Hawaii haha. I ended up ordering a 5mm last night!

 

[scubadada]

I did the Red Sea for two weeks in April-May, I dived a full 7 mm and was quite comfortable, could probably dived my 5 mm with my 5/3 mm hooded vest.

 

[BoltSnap]

I will be diving the Red Sea on this trip, expecting 3 dives a day for 6 days. Ive never been remotely cold in my 3mm but I've also never done 3 dives a day or gone diving anywhere colder than Hawaii haha. I ended up ordering a 5mm last night!

I was diving in Sharm El-Sheik this mid-March and I was wearing a 5mm suit with 5mm hood. I was freezing below and above the surface. The air temp was cold and water was around 21C. Making several dives a day over several days makes you get colder much faster since cold is cumulative. I had a 3mm full suit with 3mm shortie but I didn't use them, straight to the full 5mm suit.

If you are going to dive the red sea in mid summer, then 3mm. It will be very hot on the surface there.

 

[RIHappyDiver]

@jwoolste the great thing about a 3mm is it takes up such little space in a travel bag that you could probably take it along and switch over to the 5mm if you start getting even slightly cool. If you start getting cool and wait to switch it could take longer for you to be warm even in the 5.

 

[BoltSnap]

@jwoolste the great thing about a 3mm is it takes up such little space in a travel bag that you could probably take it along and switch over to the 5mm if you start getting even slightly cool. If you start getting cool and wait to switch it could take longer for you to be warm even in the 5.

This is true, I used the suits to wrap them around other more "sensitive" equipment to protect it.

 

[UWDawgDiver]

I find that a hooded vest is one of the best "bang for your buck" in terms of increasing the warmth of an existing suit, but it's still a step below a full 5mm. Like you, I dive a 3mm almost all of the time, but if I'm doing 3 or more dives in a day I add on a 5/3 hooded vest (I have the Bare Ultrawarmth, which I think is great, but there are plenty of good options) otherwise I start to feel unpleasantly cold by the end of the last dive.

For a liveaboard in temperatures where I would normally wear a 3mm if I was doing a single dive, and where I'm diving multiple times a day for multiple days, I always bring my 5mm (which is another step up in warmth above the 3mm+hood). I'm usually happy on day 1 in the 3mm, but by day 2/3/4, the "integrated lack of exposure" builds up and I start to feel cold. My 5mm, which has much better wrist and ankle seals, saves me from that! There's nothing worse than feeling cold to the bone on day 4 of your expensive liveaboard!

TLDR: I always bring a 5mm on a liveaboard for water temperatures that I would otherwise dive in a 3mm because the cold "adds up" by day 3 or 4. That being said, if you are super comfortable in your 3 mm, a hooded vest is a great upgrade to warmth, but I would personally get cold on a liveaboard even with that.

Do you wear your 5/3 hooded vest under your full 5mm wetsuit? Do you find that it makes the fit of the full wetsuit too tight?

 

[veryfastfourier]

@UWDawgDiver I always wear my hooded vest under the full wetsuit, otherwise the water between the suit and the vest flushes too easily and a lot of the thermal benefit is wasted. The hooded vest under the wetsuit works much better, in my opinion - there's just a lot less flushing of water in and out of the suit-vest. There are many previous scubaboard threads that are strongly in support of vest under suit, i.e. this one.

With regards to the fit, it really depends on your suit! With a well fitting or slightly tight suit, it's obviously going to make things a little tighter and you will feel a bit more restricted. On the other hand, my 5mm is slightly too large in the chest area (I'm a tall skinny guy - always hard to find good sizes), so the hooded vest actually makes my 5mm fit better!

 

[Altamira]

Spend the money and get a 5mm Bare Reactive wetsuit. You will be comfortable, warm, and will not regret the cost. They are a bit pricey, but well worth it. I have a 3 and 5 mm Reactive and could not be happier. Both are significantly warmer than my other two Bare wetsuits (3 and 5 mm) from their Elastek line.

 

[El Diablo]

Can I easily achieve the same warmth of a 5mm wetsuit by layering under/over a 3mm wetsuit with a vest/neoprene shorts etc? A 3mm is ideal for most of the diving I do but I will be doing repetitive diving on a Liveaboard this summer and have been advised that I will be more comfortable in a 5mm wetsuit after repetitive diving.

Although it all depends on your resistance to cold, usually a 5mm alone will be warmer than layering a 3mm with a 2mm vest. Also, it strongly depends on the brand and what kind of neoprene thicknesses they use in the different body panels. Usually arms and other articulated areas have thinner neoprene for added flexibility. You also need to clarify what's the water temperature, water in Italy in summer has different temperatures than Egypt. Then comes the depth, there are thermoclines at different depth and depending on the area and currents, temps can drop considerably.

Mind that you will be doing repetitive dives. That 3mm might be sufficient at the beginning but as you get tired, you'll feel cold.

That wetsuit will also be compressed with depth and depending on its age and usage, its elasticity and resistance to compression will vary. That means that 2 independent layers of 3mm will normally compress more than a single 5mm piece as long as they are both in similar condition. In addition, layering will reduce flexibility and depending on the fit of the wetsuit, those layered areas might restrict blood circulation making you feel even colder.

IMO, get a good hood even if you think you will not need it, you can lose from 20 to 40% of body heat from the head. Eat a low weight but high caloric meal between dives (basically low quality food and sweets) and try to dry your wetsuit as much as possible between dives. There's nothing worse than jumping on a cold wetsuit when you are already having goosebumps on the deck.

Finally, warm yourself immediately after finishing the dive, remove everything and turn it inside-out so the part that touches your skin dries first. Get a rush guard in addition, if you feel cold between dives wear it underneath the whole thing.

* One more thing, although very personal, pee before diving and if the wetsuit is yours and / or you don't mind the smell and comments if it is rented rented, don't hold your pee UW, your body will spend extra calories in order to keep it at body temperature. That's the reason actually why we feel the urge to pee when diving, our body wants to get read of the extra load to save energy

Have fun.