If you are new to drysuit diving, you may not know how tight your neck seal should be. When you first buy a drysuit, the suit will come with a very tight neck seal to allow for you to adjust the seal to fit your neck size. But you may be wondering why it’s important not to dive with an excessively tight neck seal.
It is important not to dive with an excessively tight neck seal, as a very tight neck seal will restrict blood flow to your brain, which in a worst case scenario can lead to brain damage and be dangerous. A very tight neck seal will also be uncomfortable and will be difficult to get over your head.
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How tight should a drysuit neck seal be?
Your drysuit neck seal should be snug enough to form a watertight seal against your skin, but it should not be too tight.
When you are new to drysuit diving a snug neck seal may feel a bit uncomfortable at first before you go diving, but once you get in the water this uncomfortable feeling should go, so long as it’s not too tight. If you begin to feel any of the symptoms listed below, you should surface immediately and remove your drysuit as quickly as possible.
The drysuit neck seal should be positioned on your neck as low as possible.
An overly tight neck seal can slow the blood flow to your brain
A neck seal that is too tight may restrict blood flow to the brain, and where blood flow and hence the flow of oxygen to your brain is restricted, this is called Ischemia.
Brain ischemia (or cerebral ischemia) is the name for a decreased blood flow to the brain, which is a condition when there’s insufficient blood flow to the brain to meet metabolic demand. This will lead to poor oxygen supply, which is referred to as cerebral hypoxia. In a worst case scenario brain ischemia can lead to an ischemic stroke and to the death of brain tissue.
What does lack of blood flow to brain feel like?
If there is a lack of blood flow to your brain this may result in symptoms that include:
- Dizziness and vertigo.
- Double vision.
- Weakness on both sides of your body.
- Difficulty speaking or slurred speech.
- Loss of coordination.
- Light headedness or fainting.
If you feel lightheaded when you are on the dive boat after putting your neck seal on (or any of the above symptoms for that matter), unzip your drysuit and take the suit off. This is a clear indication the neck seal is way too tight.
Before you dive in your drysuit, you’ll need to cut a strip off from the drysuit neck seal to make the seal bigger to fit around your neck to a comfortable size. See video below.
What to do if your drysuit neck seal is too tight?
When you first buy a drysuit, the neck seal should be too tight, which is to allow for adjusting the tightness to your neck diameter. Adjusting the tightness of your neck seal is easily done by cutting a ‘ring’ off the top of the neck seal. To do so use a box night, Stanley knife or even a surgical knife. Don’t use scissors, as it will be difficult to cut the material in a straight line, and you may damage the neck seal.
Most drysuit neck seals have size-rings around the seal (see video below), which is there to help guide your cut and increase the neck size. But be careful not too cut too much off, and only cut-off a small amount at a time and try the neck seal for size after each cut. If you cut too much off the neck seal, it may make the opening too big so it won’t seal against your neck.
Pro scuba diver tip: A tip with a new drysuit is to stretch the neck seal over a 12 litre scuba dive tank, if you have one. Leave the neck seal stretched over the tank for up to a month, or for at least a week. If you don’t have a scuba dive tank, see if you can find something with a similar diameter. For your information, a 12 litre dive tank diameter is 171mm (6.73 inches).
How do you cut a dry suit seal?
To cut a drysuit neck seal you are best to stretch the seal over a dive tank. Then cut around the neck seal by following one of the size-rings, but these rings or bars are designed to help prevent the neck seal from ripping. So always cut above one of these rings, and only cut one ring at a time. After each cut, test the neck seal to see if the fit is snug. This is best explained by video, as below:
What happens if your neck seal is not tight enough?
If the neck seal on your drysuit is not tight enough, there a chance it will leak and let water into the drysuit. If the neck seal is loose, water will gush into your drysuit. In both cases if the neck seal is not tight enough, you would have to replace the neck seal.
Make sure nothing is caught in the neck seal like clothing or undergarments
When you put your drysuit over your head and the neck seal is in place around your neck, make sure nothing is caught in the neck seal. The neck seal should be flush against your skin to create a watertight seal to stop water from entering your drysuit.
You may also like to read about how tight a drysuit should be. This article includes a drysuit fitting guide too and how to check whether it’s too tight before buying.
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