Making a Monofin and FAILING: Things I learned the hard way (read for a good laugh)

[LittleSiren24]

Got into the mermaid craze after my friend ordered a mermaid tail and swam in my pool. So, off I went on my journey to make my own. First step: The monofin

The monofin i wanted to create was a good size and just the right about of fullness I wanted. The first material i chose was Plexiglass... because I'm an idiot. I cut the plexiglass with my friends dremel, which really just melted it apart, but no more than seconds later, one of the pieces snapped off.... and more continued to snap off as I brought home it's shattered corpse. Ok, so that didn't work.
TL;DR DON'T USE PLEXIGLASS!

Ok take two: After scanning more materials (skipping over Polycarbonate/lexan because, again, i'm uneducated)
I used plastic wall paneling. It's thin, flexible, durable, and comes in a 4x10 FOOT sheet. Lots of room for play. I decided I wanted it a little thicker, so i made three layers. Gluing this stuff together is useless because NO GLUE WILL STICK TO IT. Just for the record, I used Scotch Maximum Strength and Loctite Vinyl, Fabric, and Plastic flexible adhesive.

What went wrong? I made a sleeve out of the same material the tail was going to be made of because I had nothing else. The fabric was TOO stretchy and would not hold my feet.
Back to the drawing board:
Tighten the fabric. Still too loose. (btw, modeling mine after Fin Fun's design.)
Back to the drawing board:
Duct tape the shit out of a pair of cheap sandles. Sandles stayed, but the straps broke.
Back to the drawing board:
Cut thin slits into one layer of the plastic and make fabric straps for feet. Plastic came apart in the fabric sleeve and dragged through the water.
Back to the drawing board:
DUCT TAPE THE SHIT ALL AROUND THE EDGE OF THE PLASTIC. Still no better.

After that, I gave up and bought a Docooler fin on Amazon https://www.amazon.com/Mermaid-Swimmable-Swimming-Flippers-Kids-New/dp/B01J9W22UU/ref=sr_1_4?ie=UTF8&qid=1470026355&sr=8-4&keywords=docooler+mermaid+fin
If anyone wants to give me some advice, that would be great. I have the Docooler as a backup, but i'm pretty financially deep into making my own... and I'm obsessive and want to make this work. If you wanna just comment that I made you laugh, that is appreciated as well.

[TheSaltySiren]

There are a bunch of threads on here about making your own mono fin. Plexiglass is the worst and can shatter and cause extensive injurys. I would try lean, it is not as hard as you may think to work with.

[Mermaid Whisper]

^^ What she means to say is Lexan, or polycarbonate. It's what Fin Fun uses for their monofin, and you can get it in different thicknesses for stiffness and propulsion!

[Merman Storm]

Did Fin Fun change? The monofin I got from them a few of months ago used a mix of recycled plastics, mostly polypropylene and polyethylene. It is brown in color, and has fine ribs molded into it to control flex.

Polypropylene, or PP, is actually an interesting plastic to consider in place of Lexan. PP is lighter (it floats), more durable, and costs less. On the downside, its harder to find, and virtually no glue works with it. You need to use fasteners (nuts and bolts).
If you want to try it, you can get it here: http://www.mcmaster.com/#polypropylene/=13juxaz
It's a little more flexible than Lexan, so get one size thicker than you would normally.

For mechanical fasteners, I recommend perforated base weld nuts you can find at the bottom of this page: http://www.mcmaster.com/#stainless-steel-flange-nuts/=13jv1h8

[PearlieMae]

Ya know...The search function could save you lots of time and headaches, not to mention money!

In fact, there's an entire section on tailmaking! Research can be a wonderful thing.

Edit: No, they didn't change. I don't think Finfun ever used polycarbonate. Polypropylene is interesting, but I'm too floaty as it is!

[Merman Storm]

Its not very floaty, its like 95% of the density of water. You can always add some weight. Adding floats to a polycarb tail would be much harder.

In searching this site, I've found Google does a better job than the site search tool. Enter "mernetwork" along with your other search terms.

[Mermaid Whisper]

http://uploads.tapatalk-cdn.com/20160802/87bec3d42b0339a427da20d8427f87e1.jpg

Excuse my dirty floor, but this is my monofin insert from the end of April. I received it May 3rd. It's pretty stiff, and it's definitely black! I just haven't swam in it yet. Hope this helps, Storm!


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[PearlieMae]

Good to know, Storm! I never thought to add Mernetwork to the search terms! Thanks! :)

Whisper, are there footpockets?

[Merman Storm]

It looks just like the one I have. On mine, the foot pockets are part of the neoprene cover. I think the corner of that just shows at the top right of Whisper's photo.

I found it too flexible, and made a new one out of some scrap polycarb I had in the shop. I also gave my new inset a 30 degree bend right at the toes, so the fin streamlines better when you coast.

Eventually, I'll try polypropylene.

[Mermaid Whisper]

Yes, that's just the plastic bit. They're in the neoprene cover. Unfortunately, your feet are right up against each other and there's nothing holding them onto the fin, since they're only little tubes on top of the cover!

Storm, thanks for the heads up! I have no idea what tailswimming is like just yet :)


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[PearlieMae]

Well, that doesn't sound safe, comfortable OR effective! Maybe gluing some inexpensive swim shoes might help?

[Mermaid Whisper]

Well, that doesn't sound safe, comfortable OR effective! Maybe gluing some inexpensive swim shoes might help?

Good idea! My Walmart has swim shoes for $5! Thank you :)


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[Merman Storm]

Safe: You can easily and quickly get your feet out, so in that sense, its safe.

Comfort: It does press your feet together, but its not too bad. The Two Tails foot pocket is worse. Separate foot pockets would be better, but you best bolt them on to the polypropylene. Bolting on cycling shoes would be the best, because you would be wearing actual shoes sized to you and designed to hold feet for hours at a time.

Effective: I found the Fin fun cover held my feet adequately given how flexible their fin was. You cannot put in sufficient force to pull your feet off the fin because the fin just flexes and spills the water. For me, given my size and strength, it provided poor propulsion. But it does provide propulsion.

After I made my stiffer polycarb fin I found the Fin Fun cover was insufficient. I added an extra neoprene strap to the fin, and now its fine.

The result is I made 4 modifications to my Fin Fun:

Polycabonate insert.
Bent the insert 30 degrees.
Added an extra foot strap to the fin.
Added a 2" elastic waistband.

[Merman Storm]

Good idea! My Walmart has swim shoes for $5! Thank you :)


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I just looked at Walmat. I did not know these existed! Thanks Whisper for the info.
They look like they may be just as comfortable as cycling shoes, but at a much lower cost. Also, its hard to yank your feet out of cycling shoes in an emergency, something that has always worried me. Their sole may be sufficiently thick that you can use wood screws to attach them to the fin. Screws short enough that they do not go all the way through to your feet, yet still long enough to hold. You may need 20 per shoe, but so what? As long as it works.