Question Semi-Dry squeeze??

[WestyWest]

I recently got a ScubaPro Nova Scotia 7mm semi dry in small. By their size chart I fit right at small and medium short.
It feels like it fits fine and the shop & instructors don’t see any issue.

However, on my first deep dive with it at about 40ft I was no longer able to breathe fully. I couldn’t take a deep breath, and I could only get about a half breath. Having never felt this I had a bit of panic and after not being able to catch my breath went to the surface.
It took inverting and unzippered to open my suit back up and catch my breath.

I thought semi-dry seals were supposed to limit water flow, not pretend to be a dry suit.

Do I go up a size? It has me tempted to layer with a regular wetsuit than rock a semi-dry.

Tl;dr
Semi acted like a dry suit and suctioned onto me.

 

[grantctobin]

I recently got a ScubaPro Nova Scotia 7mm semi dry in small. By their size chart I fit right at small and medium short.
It feels like it fits fine and the shop & instructors don’t see any issue.

However, on my first deep dive with it at about 40ft I was no longer able to breathe fully. I couldn’t take a deep breath, and I could only get about a half breath. Having never felt this I had a bit of panic and after not being able to catch my breath went to the surface.
It took inverting and unzippered to open my suit back up and catch my breath.

I thought semi-dry seals were supposed to limit water flow, not pretend to be a dry suit.

Do I go up a size? It has me tempted to layer with a regular wetsuit than rock a semi-dry.

Tl;dr
Semi acted like a dry suit and suctioned onto me.

Neoprene compresses with depth, not expands. Unless you had a large air pocket in your suit on the surface, I don’t think this sounds much like a suit issue. That said, how does it feel on the surface?

 

[WestyWest]

Neoprene compresses with depth, not expands. Unless you had a large air pocket in your suit on the surface, I don’t think this sounds much like a suit issue. That said, how does it feel on the surface?

Feels a tad uncomfortable on the forearms and calfs, a bit on the shoulders as well. In shallow dives it’s about the same. Just a tad uncomfortable on the extremities, but no signs of constriction.

 

[Brett Hatch]

A semi-dry is just a wetsuit with good seals. It will not prevent water flow, and it will not prevent air flow, it just slows them down. As you descend, the pressure increases, which will compress any air bubbles trapped inside, as well as the neoprene in the suit. This compression really should not result in a suit squeeze like a drysuit would.

It sounds like the suit might be too tight in the chest. Trying putting the suit on on the surface. Verify that you can take full breaths into your chest, and full breaths into your belly. Try doing a little exercise to get your heart rate up, and verify that you can still breathe well (don't work too hard, it's gonna be really hot in there).

If all that checks out, then the suit fits. In that case, I think you may have encountered a different issue. What was your mental state like before the dive? Were you in a good place, comfortable with your buddy, comfortable with the dive plan? Was dive in conditions similar to what you are used to, or more challenging conditions?

 

[WestyWest]

A semi-dry is just a wetsuit with good seals. It will not prevent water flow, and it will not prevent air flow, it just slows them down. As you descend, the pressure increases, which will compress any air bubbles trapped inside, as well as the neoprene in the suit. This compression really should not result in a suit squeeze like a drysuit would.

It sounds like the suit might be too tight in the chest. Trying putting the suit on on the surface. Verify that you can take full breaths into your chest, and full breaths into your belly. Try doing a little exercise to get your heart rate up, and verify that you can still breathe well (don't work too hard, it's gonna be really hot in there).

If all that checks out, then the suit fits. In that case, I think you may have encountered a different issue. What was your mental state like before the dive? Were you in a good place, comfortable with your buddy, comfortable with the dive plan? Was dive in conditions similar to what you are used to, or more challenging conditions?

I’ll do an exercise test when I get home. Thanks for the advice!

Deepest dive in a while (plan was 70, recent was 30), I was tired and we were doing a rope drop from a buoy (I’ve always done slope decent). All new gear. I was extremely task loaded, but the rest of my dives were a lot of fun and felt fine especially the mid day shallow dives with no suit.

 

[RyanT]

As @Brett Hatch mentioned, a semi-dry is just a good wetsuit. If your suit has good seals and you hit the water just right, you might not initially get much water in your suit. Without a layer of water between you and the suit, you will get squeezed. I've stepped off the boat a few times and started to notice a substantial squeeze by the time I hit 10'. I just slip my hand under the collar and pull it to get water in; that fixes the problem. Sounds like you experienced something similar.

 

[Zef]

I disagree a bit with Brett Hatch, some semi-drys are constructed so well that they indeed can be like a drysuit, the main difference being they don't have socks/boots attached. I have a Waterproof Combat SD 7mm semi-dry that I am positive that I could install a chest inflator and forearm dump valve on it to convert to a dry suit. The seals are so effective that I keep the ankle seals/cuffs untucked otherwise I can't vent the air in the suit and descend. At the end of my dives I am nearly completely dry above my knees.

Suit squeeze with a semi-dry is real thing. If you can withstand a quick burst of cold water then you can pull your neck seal and lets some water in, that should help alleviate the squeeze.

I have seen at least one diver dive with a 2nd LP inflator hose with an air nozzle attached. The nozzle is used to shoot air in through the wrist cuff of their suit, specifically to alleviate squeeze:

Cant's say for sure, but the feeling you had of not being able to take a full breath and the resultant panic could be that you just need to acclimate to the suit, and/or it could also be that your neck seal is too tight. Find a shop that can do custom alterations and have them check your neck seal and enlarge if need be.

-Z

 

[Brett Hatch]

I disagree a bit with Brett Hatch, some semi-drys are constructed so well that they indeed can be like a drysuit, the main difference being they don't socks/boots attached. I have a Waterproof Combat SD 7mm semi-dry that I am positive that I could install a chest inflator and forearm dump valve on it to convert to a dry suit. The seals are so effective that I keep the ankle seals/cuffs untucked otherwise I can't vent the air in the suit and descend. At the end of my dives I am nearly completely dry above my knees.

Suit squeeze with a semi-dry is real thing. If you can withstand a quick burst of cold water then you can pull your neck seal and lets some water in, that should help alleviate the squeeze.

I have seen at least one diver dive with a 2nd LP inflator hose with an air nozzle attached. The nozzle is used to shoot air in through the wrist cuff of their suit, specifically to alleviate squeeze:

View attachment 738713

Cant's say for sure, but the feeling you had of not being able to take a full breath and the resultant panic could be that you just need to acclimate to the suit, and/or it could also be that your neck seal is too tight. Find a shop that can do custom alterations and have them check your neck seal and enlarge if need be.

-Z

I stand corrected. Thank you, I've never heard of this phenomenon. Perhaps the OP is experiencing squeeze after all.

Do you reckon that there is a way to test for this?

 

[WestyWest]

I disagree a bit with Brett Hatch, some semi-drys are constructed so well that they indeed can be like a drysuit, the main difference being they don't socks/boots attached. I have a Waterproof Combat SD 7mm semi-dry that I am positive that I could install a chest inflator and forearm dump valve on it to convert to a dry suit. The seals are so effective that I keep the ankle seals/cuffs untucked otherwise I can't vent the air in the suit and descend. At the end of my dives I am nearly completely dry above my knees.

Suit squeeze with a semi-dry is real thing. If you can withstand a quick burst of cold water then you can pull your neck seal and lets some water in, that should help alleviate the squeeze.

I have seen at least one diver dive with a 2nd LP inflator hose with an air nozzle attached. The nozzle is used to shoot air in through the wrist cuff of their suit, specifically to alleviate squeeze:

View attachment 738713

Cant's say for sure, but the feeling you had of not being able to take a full breath and the resultant panic could be that you just need to acclimate to the suit, and/or it could also be that your neck seal is too tight. Find a shop that can do custom alterations and have them check your neck seal and enlarge if need be.

-Z

This, this sounds like the answer.
My instructor tried to shoot air down the back with the zipper open when at the surface but I couldn’t get my hips / legs to un-suction. Opening the neck and pulling on my gut wasn’t enough either until I inverted.

I have large calves so sections of the suit plus the seals may section out areas so I’m not sure an inflator would be a true fix for me.

Could trimming the seals or nerfing them somehow be an option? I mean it’s supposed to be semi dry not full. Hah.

Thanks again for the discussion and help

 

[tggm]

I also have this problem with a nova scotia semi-dry. I bought the 2XL and it fits comfortably on the surface (except discomfort on the neck and throat which I'm trying to get used to). The suit is quit spacious on the chest, belly and groin.

However I immediately noticed two issues: Bigger air bubble inside which makes descending difficult (had to add 1Kg) and squeeze below 5/6 meters. The squeeze is especially painful on the groin area since the suit doesn't fit that area perfectly and there is a lot of empty space.

Usually with wetsuits I would just open the suit at wrists and/or ankles to let water in.

With this semi-dry it's difficult to open at the writs/ankles so I just open by the neck and let some water in. At the surface, while upright, I open to let some air out. During the dive I break the neck seal to remove the squeeze. It's uncomfortable to put cold water in but the squeeze is way worse.

Also, people keep saying that semi-dry suits are the same as wet suits or that a semi-dry is a wetsuit with better marketing which I think is utter nonsense. Water doesn't get into this thing unless I grab the seals and pull. At least with the nova scotia.

Finally @WestyWest you probably need to try a bigger suit regardless what the size chart and the instructors say. When I rented wetsuits I always had to argue that I wanted a 3XL size because the shop's people insisted on a 2XL. Even when I bought the nova scotia 2XL the sales guy kept insisting on a XL.

Remember: If when you put your suit on the only thing you think about is "when am I going to get out of it" then you need a bigger size