Drains for a fabric tail

[Merman Storm]

I have three fabric tails. Recently I have been doing quite a bit of swimming at the beach. I find the tips of the fin get full of sand. It collects in the fabric, turning the fin tips into little sand bags that hang from the monofin tips. Ive had these get as large as a child's fist.

I need drains. But, these are commercial tails. Any drains will need to by retrofitted by me. In addition, one tail (the Toothless tail) has a double layer of fabric. Sand collects between the layers. ( I think it gets through the weave of the fabric. The sand at this beach is quite fine). What is the best way to add drains? What I have thought of:

1) Just cut the fabric, making a little hole. I'm worried this will result in weak spot and tear when the tail is in use.
2) Cut a hole, and sew up the edges. This seems like it would need a big hole to allow sewing, which will allow the monofin to show through. Also, it will be hard to do for the double layer tail, as I need a separate hole in each layer to allow the sand to get out from between the layers.
3) Cut a hole and use some silicone sealant around the edges to stop any tears. This seems like a possible method. Am I missing something?
4) Punch a hole and fit an eyelet in there to reinforce the fabric. I'm not sure this would work with Spandex, or if the eyelet itself will cut the fabric, making a mess.

What will work? Any other methods?

[Moonchild]

I have a similar problem, I didn't add any drainage system when I made my spandex tail and now it fills up with water as I swim and looks like a balloon😂
I've been wanting to fix it but I don't want the monofin to show through. My biggest concern is how to conceal the hole.

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[Merman Storm]

For the double layer tail, concealing the monofin can be done by offsetting the holes in the two layers. For a single layer tail, you can make the hole very small so it's hard to see, or glue some fabric to the monofin right where the hole is. With small holes, getting sufficient drainage can be done by making several holes.

[Moonchild]

That's smart!! Gluing fabric to the monofin is a brilliant idea!! Seems so obvious now, I can't believe I never thought of it

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[Merman Andrew]

For a fabric tail, I'm not sure cutting holes in the fabric is a good idea, unless you reinforce it as you suggested. If the bottom of your tail is open the best thing to do is to close up the bottom with a zip so the sand can't get in there in the first place. I haven't tested this theory myself but it would seem that the most likely place the sand is getting into the tail is through the opening in the bottom.

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[Merman Storm]

The tail is already closed with a zip. The sand still gets in. It also gets in on my Lunocet tail, and that one is sewn shut.

I figure it gets in by two methods. One is right through the fabric. The sand is quite fine. It gets in all along the entire length of the tail. It may only be a tiny amount in every square foot, but it collects at the fin tips. There it may leave again, but the area is so much smaller that there is a net gain, the sand keeps building up. The other way is at the waist. The wast band of the tail is not very tight, and the tail keeps slipping down. Every time I pull it back up, a little sand gets in. I plan on adding a much more aggressive waist band so the tail stays in place. (I don't have much of a waist, so I need to rely on friction alone to keep the tail in place). That may help. But the Lunocet tail already has a good waist band, and it still collects sand (just not as much).