Trim Your Drysuit Gaskets Right May 30 2014

If your drysuit gaskets are too tight for comfort, they may have to be trimmed. Some drysuits (including Mythic Gear's) come through from the manufacturer with the gaskets completely closed at the ends, and these must be trimmed before you can even try the suit on.

Closed-End Gaskets 

It's important to trim gaskets correctly. Poor trimming can result in premature gasket failure, which is inconvenient and somewhat expensive to repair. Should you wreck a gasket on a brand new suit, the manufacturer may be reluctant to offer a refund or size exchange.

We'll use closed-end gaskets in this example. If your gaskets are open-ended, the process is the same except for step #2 and as noted in step #3.

1. Turn the suit and gasket inside-out. Notice the trimming rings molded into the gasket.

Sleeve and wrist gasket, inside-out. Note molded trim rings.
2. Using sharp scissors, clip off the closed end well above the first trim ring. This cut need not be especially clean.

Left: Trim the tip of closed-end gasket. Right: This cut need not be very smooth.

3. Cut down toward the first trim ring. On a closed gasket where you just cut off the tip, start nearly perpendicular to the edge and rapidly change the angle of the cut so that by the time you reach the first ring, it's in line with the ring. On open gaskets, start the cut at a shallow angle, heading gradually down before leveling out in line with the ring.


The next cut begins at a steep angle (left) and quickly levels out with the trim ring (right)

4. Cut all the way around the ring. The keys to a clean cut are: hold the gasket as flat and tight as possible, and make each stroke of the scissors as long as possible.

A properly-trimmed wrist gasket has a nice smooth edge.

5. On closed-end wrist gaskets, the first ring is usually quite close to the end, and its diameter is so small that it is difficult to make long, clean scissor strokes. Work carefully and do your best. Make sure that each successive stroke begins precisely in the apex of the previous one.

6. Make sure that the end of the cut aligns precisely with the beginning, leaving a perfectly smooth edge all the way around.

7. Slight imperfections that stick up can be acceptable. Notches in the edge are unacceptable, because notches can easily turn into tears. If your cut left a notch, repair it by cutting at a very shallow angle from its deepest point to meet the clean edge an inch or two away. Do this in both directions from the deepest point of the notch. The result should be a very shallow, perfectly smooth-edged depression in the top edge of the gasket.

A badly-trimmed wrist gasket. The notch could become a tear the first time you try it on, but it's not a lost cause. Work carefully to smooth out the rough edge.

8. Turn the suit rightside-out and try the fit of the gasket. (You don't have to put the suit on each time: you can just insert your wrist or neck through the gasket you're working on.) If it's too tight, trim down to the next ring and repeat.

9. A properly-fitting gasket should feel just a little bit snug, not uncomfortable. It only needs to be tight enough to remain in contact with your skin no matter how your body moves. When the gasket is submerged, water pressure helps create the watertight seal.

Drysuit with properly trimmed wrist and neck gaskets

 Other Methods:

  • Some people report better results with a razor knife than scissors. We have not had luck with this method.
  • Some people report good results clamping one side of the gasket against a tabletop, stretching the gasket sideways, then cutting through both layers at once with scissors. (As an alternate to clamping, some suggest having a friend hold one side while you stretch the other side with one hand and cut with the other.) We find it difficult to keep both layers perfectly aligned with this method, and impossible to finish the cut cleanly.

Trimming Mythic Gear's New Closed-End Gaskets

Cutting to the first (top) trim ring on Mythic Gear's new closed-end gaskets produces a very small opening that is too tight for most people, and trimming just one ring at a time can be tedious if you ultimately need to trim down 5 or more rings. The following tables show the rings (trim lines) that should provide a pretty good fit for most people, based on the circumference of their wrists and neck. (Use a dressmaker's fabric measuring tape.)

The rings on the tables are numbered from the base of the gasket (where it attaches to the fabric of the drysuit), so that ring #1 is the one closest to the fabric. That way, even after you've trimmed off a few rings, you can still count from the bottom and get the right ring. We recommend making your first cut at least 2 or 3 rings above the recommended one (i.e., closer to the opening) and working your way down one at a time.

Neck Gasket

 Inches Centimeters Trim Line
<11 28 13
11.5 29 12
12.5 32 11
13.5 34 10
14 36 9
14.5 37 8
16-17 40-43 7
17-18 43-46 6
18-19 46-49 5-3


Wrist Gasket

 Inches Centimeters Trim Line
4.5 11 10
5 13 9
6 15 8
6.5 17 7
7 18 6
7.5 19 5
8 20 4
8.5 22 3
9 23 2


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